Lactation and selected medical conditions. Video + transcript Professor Pamela Berens 11 August 2026

About Professor Berens

Professor Pamela Berens is an Obstetrician and Gynecologist serving as a Professor of Obstetrics, Gynecology, and Reproductive Services at the McGovern Medical School in Houston, Texas.

Topics

This talk includes information about breastfeeding and

• Hypertension

• Hypothyroidism

• Respiratory tract infections

• Deep venous thrombosis, pulmonary embolism

• Rheumatologic drugs

• Immunotherapy

• Maternal infections including

  • Herpes simplex

  • Herpes zoster

  • Tuberculosis

  • Hepatitis A, B, C

  • Urinary tract infections

• Pink discoloration of milk (serratia marcescens)

Transcript

Pam I'll get underway by acknowledging the traditional custodians of the land on which I live and work, the Turrbal and Yuggera peoples, and I pay my respect to elders past, present, and emerging. It's lovely to see you all showing up to welcome into the NDC Institute tonight Professor Pamela Berens, who is an Obstetrician and Gynecologist serving as a Professor of Obstetrics, Gynecology, and Reproductive Services at the McGovern Medical School in Houston, Texas. Professor Berens has kindly agreed to talk to us tonight on selected maternal medical conditions and their impact on breastfeeding.

I wanted to say that from the very early 2000s, as a GP and IBCLC who was passionately interested in breastfeeding and lactation support and what was emerging in the breastfeeding research literature, Professor Berens' name has featured regularly throughout my professional life over the past 25, 26 years, making very substantial contributions in research and development of clinical protocols in breastfeeding medicine. For that, as well as for your presentation tonight, Pamela, I am very grateful to you. Could I hand over to you and ask you to take the floor?

Professor Berens Thank you. It's my pleasure to be here, and thank you so much for inviting me to speak to you all. Always so much fun to talk about what we know and don't know related to breastfeeding. When talking about maternal conditions and impact on breastfeeding, it's so hard for me to choose, and I likely have more information than you need, but I do welcome any pressing concerns that people have. I don't know that I'll be able to monitor the chat while we do this, but I can always get back to you later. I do like to know what the hot topics are that people are concerned about when it comes to breastfeeding. So with that, I'll go ahead and get started.

There are a number of different things that I'd like to touch on. I'm going to start with some of the things that we commonly treat as obstetricians. I know that people have various backgrounds, so not everyone does the maternal side. I'm going to touch on hypertension, thyroid disease, some of the rheumatologic conditions, I'm not going to go into a ton of detail about all the different ones because there are just a lot of options here. I'll also touch on infections and cancer. I do have a picture of my zebras here, but I have to say that that's the opposite of what I'm thinking. I don't want these things to be zebras. They're actually things we encounter every day, so we need to have some comfort with them.

Oftentimes in lactation, when we don't have good answers, the tendency is to say we shouldn't breastfeed, as opposed to the opposite, where we assume that breastfeeding is normative and healthy and the best choice, and then ask for evidence the other way. So it's a change in mindset to some extent. I'm going to give you various cases to think about throughout the conversation. Most of the time I'll have answers, but not for this first one. This first one is intended to help you think, and this is actually an extremely common situation for my practice, probably see it on a weekly basis.

So this is a 41-year-old gravida 2 who's seeking antenatal advice about breastfeeding. Her prior child was born 8 years ago and she was unsuccessful at that time with her desires for continued breastfeeding. She did initiate breastfeeding but quit after a couple of weeks. Her pregnancy has thus far been complicated by her age being 41. She also has a history of hypertension that's controlled on Pokardia. She failed her sugar test, so she now has gestational diabetes and is on metformin for that. She has a BMI of 40. The question is, how do we support this woman who would like to breastfeed and has a number of things going against her? Not the least of which is that she tried once before and was not successful. Much of this has to do with the support from our antenatal team and our handoff between the antenatal and the postpartum period and providing continuous support during that time.

I happen to be very spoiled in my practice setting in that we have a lactation consultant other than myself in our office. She is available if you have the ability to see us during your prenatal care. You have the ability to see her anytime after the delivery without additional fees that wouldn't be covered by your insurance. We have that smooth transition between the hospital lactation consultant and then the lactation consultant in our office to manage this. We also have the ability for the lactation consultant to meet her during her pregnancy. She comes in regularly for all first-time mothers at around 28 weeks, and also for anyone who I send or ask her to assist with because of prior not meeting their breastfeeding goals or other new risk factors such as multiple gestation. From that perspective, I am extremely spoiled in my practice, and eternally grateful for that opportunity.

This is US-centric data, so my apologies, but I show people a bit of what at least regionally we're up against. You can see that incidence of obesity from 2016 to 2020 increased substantially. That's the blue bar at the top—the incidence of obesity. The two bars at the bottom are the incidence of gestational diabetes and hypertension, which are really following that increase in body weight. That does explain some of the increase that we've seen in these comorbidities in pregnancy. I know that you've had prior lectures on obesity and diabetes, so I'm not going to go into detail on those, but I am going to start off briefly discussing that increase in hypertension that we've seen, which is nearing 10% in our population in the US for pregnancy.

Hypertension and breastfeeding [00:04:00]

Hypertension is actually multiple disorders, not just one disorder, so we lump it all together under that gestational hypertensive disorders. Some of these women have just gestational hypertension, an elevation in their blood pressure alone related to the pregnancy. Some of them have preeclampsia with coexisting proteinuria. Some have severe disease with the severe hypertension or HELLP syndrome, or on occasion, unfortunately, still some eclampsia. Then we have that group of women who have chronic hypertension diagnosed prior to pregnancy who then may or may not develop superimposed hypertension of pregnancy on top of their chronic hypertension. We really see a lot of this in daily practice.

The issue related to hypertensive disorders is that it results in other complications. Probably one of the most significant is the risk for iatrogenic prematurity. Prematurity is often caused by us obstetricians in that we have no successful treatment to reverse the disease, so we deliver them prematurely. I understand the need for that, but it results in its own set of complications. It also can have fetal growth restriction, and it can result in the baby going to the NICU or being taken away from the mother, which can result in delay in lactation, cascading into its own number of difficulties related to breastfeeding. It also often involves induction.

I do have to mention that I'm going to discuss a bunch of different medications, and magnesium sulfate is the anticonvulsant of choice where we work. That is a safe choice in lactation. The milk to plasma ratio is around 2, so it is concentrated in the milk a bit, but it's very poorly absorbed orally. The milk to plasma ratio is around 2, so it is concentrated in the milk a bit, but it's very poorly absorbed orally. It has a very low oral bioavailability in the 4 to 30% range. When you take magnesium orally, it actually works as a cathartic. So all it will potentially do is maybe make the baby more likely to pass the meconium, which actually would be a positive thing, not a negative thing. There really aren't pediatric concerns related to the magnesium exposure through breast milk. It's also much less than the magnesium exposure she's going to receive through the antenatal administration of the magnesium. Most of our antihypertensive drugs are really compatible.

One of the things that is important to do for these women with hypertensive disorders is to initiate breastfeeding early and often. We don't need to add that iatrogenic delay in the first feed if it is avoidable. If the baby needs to go to the neonatologist in the NICU, that's a different scenario. In the scenario where the baby is healthy enough to leave with the mother, we certainly want to avoid that delay. Chronic hypertension is going to require continued therapy after delivery, and most of those medications are compatible. We prefer to avoid the ACE inhibitors and the ARBs in the second and third trimester pregnancy. Those have considerable concerns related to the fetus during the pregnancy. In the newborn period, you do want to watch if the baby has some renal dysfunction with those medications. I would encourage you to choose established drugs, and oftentimes we're using Dr. Hale's reference as our medication source, but there are other sources available that can provide you with some information.

This is a recent article that came out this year related to looking at late preterm birth caused by hypertensive disorders. It was a fairly large study with nearly a little over 2,000 participants matched for age, smoking, insurance, and diabetes. They did notice that the induced group again had a higher BMI, more chronic hypertension, and more hypertensive diseases of pregnancy. That's not surprising, we know that we are prematurely inducing these babies. The good news that this study provided was that the breastfeeding initiation rate was similar between the groups that had that induction for late preterm induction. I'm not saying it would apply at 28 weeks, but the 34 to 37-week group had similar breastfeeding rates. There was a trend towards more difficulties with breastfeeding in that group that was induced—38% versus 32%. However, after they adjusted for confounding, that did not persist. So the good news is that not a lot of new information here, but nonetheless, some new information in that late preterm birth related to breastfeeding impacts of that induction for these type of diseases that we see.

This actually came from the Royal College fairly recently. I saw it as a Facebook post because that's where we get our scientific information, which gave me a headache. I've recently had a patient send me a Reddit post about why she needed to be on a medicine, which was heartbreaking to me. I appreciate social media, I definitely do, but it's not where I get my medical information. It does help with trends, so you know what people are seeing. This is a post related to the Royal College recommendations for antihypertensive medications and breastfeeding, which is a little interesting to me. I'm not sure I completely agree with it. It's a little different than what I do in the U.S. with my practice, but I thought it would be a good discussion point for us.

They actually had as a first choice enalapril, which we rarely use as a first choice. They did suggest if there was Black African or Caribbean family, then they chose nifedipine. That is a very common choice for us, and that may be partly why, although the predominant population that I care for in my role at the county hospital in Houston is Hispanic Americans. Then they suggest possibly adding some other medications if it's not controlled at that point. So I'm going to go over some of these meds that they suggested. They suggested that enalapril, which is an ACE inhibitor, is an L2 drug with a very low relative infant dose. It has a pretty long half-life though, about 35 hours. They caution the use in prematurity or infants with renal disease and suggest monitoring infant feeding and weight gain, which almost all of these drugs do, which may be related to some of the impact of the hypertensive disorder in pregnancy and growth restriction there. My concern as an obstetrician is that these ACE inhibitors are really contraindicated in the second and third trimester pregnancy. So I would really prefer that she not be on those from a pregnancy perspective. So it requires a change in medication after delivery. If she's been well controlled, that's maybe not as easy done as said.

We often continue their pregnancy medications at altered doses to wean them off or potentially wean them off if they're not a true chronic hypertensive in the postpartum period. It may be different for someone who has known chronic hypertension where I know I may want to continue the therapy versus a pregnancy-induced hypertension. The calcium channel blockers, which we actually do use a lot, such as nifedipine, are also an L2 drug with fairly low relative infant dose in that 2 to 3% range, and have a much shorter half-life. The other thing about nifedipine that's very reassuring to us in lactation medicine is it's also a drug that's sometimes used to manage vasospasm of the nipple. The concern really here is the tolerance of the mother in that it may make her blood pressure drop a little bit and she may be a little woozy if she's not actually a hypertensive in that scenario. It's also a safe drug used in pregnancy. This may be why in my particular practice setting, this is a more common choice for us.

Another one that we commonly use in the US is labetalol, which is a beta blocker. It's also an L2, has similar concerns about monitoring infant feeding and weight. Really all of the antihypertensive drugs have that concern, and has an extremely low relative infant dose in the under 1% range, and a fairly reasonable half-life between 6 to 8 hours. The one caveat related to labetalol is really not a fetal caveat so much as a maternal caveat. There are case reports of mothers testing falsely positive on a drug screen for amphetamines related to the use of labetalol. We don't use random drug screens where I work. We screen, but we screen with an oral tool called a DAST screen. We don't screen randomly using urine.

One of the reasons for that is that we use traditional risk factors for sending drug screens on women maybe 20 years ago, and we did a study where we compared that to all of the urine in the clinic for the day having a substance of misuse in it. We found that using our risk factors, we caught half of the positives. We found that we were in a way selecting people with risk factors that we were worried about, and that was very misleading. To avoid some of that cognitive bias, we stopped using that type of screening. We really found that it underestimated the substance use or misuse, and that it reflected bias in who we were testing, which was not a good thing. We stopped doing that for our practice. We will still send a drug screen, but that's when the mother admits to doing those drugs. We do screen everyone, but using an oral tool.

Those drugs that we don't like as much would be the ARBs, or angiotensin receptor blockers, such as losartan. This is an L3 drug. We don't have any breastfeeding data. Similar to the ACE inhibitors, it's contraindicated in the second and third trimester of pregnancy. However, it is 99.8% protein-bound. So even though we really don't have much breastfeeding data, it would be very unlikely for a significant amount of this drug to get to the baby. Caution in the newborn period with prematurity because of the way the drug is metabolized. With that extremely high protein binding rate, you would anticipate very low milk levels. We also don't like diuretics, although they're not believed to be harmful from the baby's perspective. They can be harmful to the mother's milk supply.

A diuretic such as Lasix is an L3 drug. It's used in pediatric units, but there's scant data in breastfeeding, which is interesting. It's a very highly protein-bound drug, so theoretically very low exposure to the baby. Our concern is that reduced intravascular volume in the mother and that having a negative impact on her milk supply. So it's not ideal, but for a different reason. I shouldn't say contraindicated, but not our first choice. I certainly still let women breastfeed if they are on a diuretic. Typically in our practice, I'm using a diuretic only in the setting of maybe a cardiomyopathy at delivery. So I have a very sick mother who I need to get some of the fluid off in addition to using some other cardiac drugs. I wouldn't have her pump and dump or throw away her milk in that scenario. We just would be concerned about her supply, but there are a lot of things in that scenario that would potentially adversely impact your supply.

Thyroid disease and breastfeeding [00:21:41]

I'm going to move on to thyroid disease. Thyroid disease is a lot of different things. It's not one thing. There's hypothyroidism, where the most common cause is going to be Hashimoto's, which is a chronic autoimmune thyroiditis. This typically involves an autoimmune problem related to thyroglobulin and TPO antibodies. In developing countries, this also can be caused by iodine deficiency with goiter, which is a very different disease than Hashimoto's. I have not seen iodine deficiency in a native US participant pregnant patient, though I have in someone traveling from out of the country on like once or twice throughout my career. It's quite rare. You can also have hypothyroidism caused by iatrogenic reasons such as thyroidectomy or radiation therapy and then subsequent hypothyroidism. There are multiple medications that have been associated with transient thyroid dysfunction as well. There's also the transient postpartum thyroiditis, which I have seen a number of times. It's reasonably hard for us to catch because the symptoms are very similar to normal postpartum symptoms. However, it can occur really as often as 5 to 8% in the postpartum period. It typically is a transient problem, but it can recur with future pregnancies. These women do have an increased risk for true hypothyroidism later in life.

The problem with hypothyroidism is it takes a while to get you back to your steady state or your euthyroid state that we're trying to replace you for. If you find out about this before pregnancy or during pregnancy and have the opportunity to correct her during that time, she should be at steady state at delivery. Now we may need to change the dosage in the postpartum period, but if she is essentially back to euthyroid, she really shouldn't have difficulties with breastfeeding. She should be back to that normative state with the thyroid replacement that we're giving her, which is usually, at least in the US, most commonly levothyroxine under the brand name of maybe Synthroid, but levothyroxine is the replacement and it's a T4 replacement that is really considered an L1 drug. It is almost entirely protein bound. If she's back to the euthyroid state, she should really be no different than that woman who does not have hypothyroidism to begin with. This should be a very good situation for breastfeeding. It's a little bit harder if the diagnosis isn't made during pregnancy because it's going to take her 4 to 6 weeks to get back to that euthyroid state. So if this is something that's diagnosed during breastfeeding, then that's going to be a little harder for her from that perspective. It's completely safe, just don't expect it to be corrected overnight.

For hyperthyroidism, interestingly, it's also an autoimmune disorder. 95% of cases are Graves' disease, which is also an autoimmune disorder. There's probably some relationship between Graves' disease and Hashimoto's. They're both autoimmune disorders. Graves' disease more commonly is going to present with some of these other symptoms such as goiter, eye disease, and this is related to TSH receptor antibodies. There are other rare causes of hyperthyroidism, seen only a couple times in my career. They're not things that roll off the tongue, but you can get it with gestational trophoblastic disease or trophoblastic neoplasia. You can get it with struma ovarii—I've seen it a couple of times with both of those disorders as an OB. You can also get it from a thyroid adenoma or toxic multinodular goiter. This transient postpartum thyroiditis can go either way. It can go hyper or hypo.

With hyperthyroidism, we need to control their symptoms if they are extremely tachycardic. Depending on how severe the disease is, you may need to use a beta blocker for that. We've discussed that those are safe to use in lactation to control the tachycardia. Not all women would need it. It depends on if she's leaning towards thyroid storm or not. Our treatments of choice are typically PTU and methimazole. Those are both potential treatment options in pregnancy and they are both L2 or safe in breastfeeding. The relative infant dose for PTU is a bit lower than it is for methimazole, but both of these meds have fairly decent data behind them that suggest there's no adverse impact on the infant's thyroid function with doses I have listed there for PTU up to 750 milligrams per day and with methimazole up to 20 milligrams per day. They both look reasonable treatments if she needs treatment in the lactational period. They do suggest monitoring infant T4 and TSH, although that would be at higher doses where we have less data. At the lower doses, there's pretty good data.

The choice that we would not like her to make in lactation is the use of I-131 to ablate the thyroid for hyperthyroidism. That is because about 27% of your dose of the I-131 is actually going to be concentrated in the breast milk. One, that's not good for the baby, but two, that's not good for the breast itself. They do even suggest concerns about the baby being on the mother's chest with I-131 therapy from some radiation exposure from that transfer in the milk. I would encourage an alternative form of treatment during lactation for her disease as opposed to the I-131. You could consider thyroidectomy, which would then just be an issue of replacing the thyroid, which is going to be its own potential problem. I would suggest if she's choosing the I-131 treatment that she plan to wean prior to starting the therapy. The drug has a very long half-life. From a pump and dump perspective, it would be more than a month's time. My concern is really that I don't think it's a wise decision to concentrate the radioactive iodine in the breast.

Moving on to asthma, this one's pretty straightforward. The asthma medications are generally safe. Most of our asthma medications now are inhaled agents, and the advantage of that is they work directly in the respiratory tree. Because of that, there is very, very little absorption from these drugs that are inhaled. That's a very nice feature for us in lactation. If she doesn't have a plasma level, it's not going to be able to transfer to the milk to get to the baby. We just have to think about how the drugs work. The inhaled steroids and the inhaled beta-mimetics are all pretty safe options for breastfeeding mothers. These drugs work most of the time. Occasionally you'll have an asthmatic that's severe enough that she'll fall into some of those rheumatologic type of disorder treatments with steroids and other drugs, and we'll talk about those related to rheumatologic diseases. That's fairly uncommon now with the better inhaled asthma agents that we have.

Respiratory infections and breastfeeding [00:30:20.]

Respiratory infections,a word about these. These infections are not related to the respiratory infection in terms of transmission through breast milk. We know that we want to continue breastfeeding through these. If you stop, you're just denying the infant the antibodies. It's really more about the medications for comfort. Benadryl, even though it's an L-true drug and it is safe, has a relatively low relative infant dose in the 1% or less range. We don't prefer that, mostly because of the potential for sedation. It's safe in breastfeeding, but I would be cautious if you had a premature infant that maybe had A's and B's and was on a monitor at home where sedation would be more of a factor.

Sudafed, which is one of the other commonly used decongestants, is a potential concern related to milk production. The relative infant dose is fairly small at around 4.7%, but there are some small studies. One study mentioned by Dr. Hale is 8 dyads with a dose of 60 milligrams of pseudoephedrine. They noticed in that particular study a 27% reduction in supply over 24 hours. This seems to be more of a concern later in lactation than early in lactation, which is a little interesting—not necessarily what we might expect. This is just a caution for that. Many of us in lactation actually purposefully will use a short course of Sudafed as one of our management strategies for oversupply. I have found it to be effective. I can't say I have actually gotten scientific evidence related to that one. That might be a good future study in our use of Sudafed for oversupply, but it does seem to work.

We really prefer the less sedating antihistamines in the lactating mother, such as loratadine or cetirizine, and those are L1 and L2. You can see they're relatively low infant dose percentages. The nice thing about these drugs is that they don't cross into the brain or cross that blood-brain barrier, which is why they are not sedating. That's a big perk for us.

DVT, anticoagulation, and rheumatologic conditions [00:33:41]

Moving on to DVT pulmonary embolism. Unfortunately, we see this, and it's more common in our mothers who have other risk factors and undergo cesarean birth. Heparin is not absorbed orally. It is a huge molecule, and even the low molecular weight heparin, or Lovenox, or enoxaparin, is still enormous. It's low molecular weight, so instead of 12,000 Daltons, it's 2,000 to 5,000 Daltons, but it's a huge molecule nonetheless, and it just doesn't pass into the milk. The problem with heparin and low molecular weight heparin is these are injections and they're not overly appealing for patients to self-administer, but they are a very safe choice in breastfeeding. I really do encourage my mothers to continue with this for their postpartum treatment from a safety perspective in lactation.

Coumarin is also safe. Coumarin is safe even though it's bad in pregnancy. It's a D in pregnancy, but it's safe in breastfeeding. The reason that it's safe is twofold. One, it's highly protein-bound. It's really only the free drug that can pass into the milk, and it's just highly protein-bound, so there's very little of it. Insignificant amounts are reported in the milk. The other reason is that vitamin K counteracts this, and we give infants vitamin K at birth. So unless she's refusing it, which has become a recent trend in the U.S., Coumadin would be a safe choice. It's just a very twitchy drug with a lot of dietary restrictions, not hugely popular for the mothers. For somebody needing a peripartum course of an anticoagulant, we still really go with the low molecular weight heparin as our first choice if that's an option for us.

Some of the newer agents or those direct oral anticoagulants or DOACs as they're being called, we really know a lot less about some of these drugs. Apixaban is an L4 with a relative infant dose that's pretty high, up to 21%, so wouldn't really be a good first choice. Rivaroxaban looks to be a better choice. It's an L2, and you can see there the relative infant dose is quite small. Half-life is also a little bit shorter. The problem is the data that we have is really just from a few dyads. It's reassuring data. If I was going to be pushed into choosing an oral agent instead of my low molecular weight heparin, then I would probably lean that way because of the relative infant dose being so low and the data that we have being reassuring, but I would counsel the mother that we don't have nearly as much data as we do with Lovenox.

Another newer choice is one of the direct platelet aggregation inhibitors, such as dabigatran, Pradaxa. The problem here is that we don't have data, but based on the molecular weight of around 600 and the very low oral bioavailability of about 6%, you would anticipate low levels. I like to have a little more data than that to give to the mothers when I'm counseling them. So if this was a drug that I needed to put her on, I would just tell her that I believe that this will turn out to be a safe drug, but we just don't have that much information yet. I would steer towards one of the drugs that we know more about. That said, I think Xarelto and Pradaxa may turn out to be good choices.

I'm going to move on to rheumatologic disorders. I really didn't break this down because that would be probably an hour lecture in and of itself. This is looking at diseases such as lupus, rheumatoid arthritis, and psoriatic arthritis. We see a lot of psoriasis in our younger population, but I see much less psoriatic arthritis. I did put it in here as one of those possible choices. These are all chronic multisystemic immune-mediated diseases, and there are really a number of different treatment options. The oral non-opioid medications are really used for pain control. These are drugs we're very familiar with, and we're very comfortable using in breastfeeding. Acetaminophen, ibuprofen, Ketorolac—those drugs are all fairly commonly used and have good safety profiles in lactation. Gabapentin is a drug that we're more commonly using for early recovery after surgeries, including cesareans. The relative infant dose is fairly small, and it's one of those L2 drugs we're fairly comfortable with. We can use these things for pain control, although they're not necessarily treating the underlying condition in these patients.

To treat the underlying condition, we have a number of choices. One is hydroxychloroquine, which is an antimalarial drug that seems to also work for immune diseases such as lupus and rheumatoid arthritis. Relative infant dose is low. Half-life of this drug is very long, but since it's been used to treat malaria for years, we know a lot about it in lactation, and it has a very good safety profile. We will sometimes turn to steroids such as prednisone. It's an L2 drug with a very low relative infant dose. The concern about steroids is not related to a short course of a high-dose burst or a long course of a low dose. The concern is related to high doses for sustained periods of time. When you get to doses over about 40 milligrams per day equivalent for prednisone, you can get some immune concerns in the infant from these higher doses. We would want to monitor in that situation—not for a short burst of a high course or not for a low dose of the steroid. You want to consider those things when you're counseling.

Azathioprine is another choice that's sometimes used. The information we have for azathioprine is a low relative infant dose between 0.07 and 0.3% under 1%, very reassuring. The problem with azathioprine is it is one of those drugs that we don't like in pregnancy, and you may want to consider monitoring the CBC and LFTs if there's any concern for immune suppression in the infant or anemia or jaundice. Methotrexate is also used to treat these disorders. It's not our first choice. This is a folic acid antimetabolite. It's interesting because in medicine we're very against this medication in lactation. The relative infant dose is actually very small, but this drug is so concerning for rapidly developing cells—which the baby has tons of—that we really are uncomfortable with its use, especially being that it remains in the tissue for extended periods of time. We know about that toxic impact on rapidly dividing cells. If, for instance, she's been on methotrexate for one of these rheumatologic conditions where it's been a regular daily dose—not for treatment for an ectopic pregnancy, but for a continuous period of time for an autoimmune disorder—we would actually tell her to defer pregnancy for 3 months to a year after therapy because this drug is so bad in pregnancy. So I think a lot of that leads to our not turning to this option in lactation. Just to know, the relative infant dose is extremely small. It's just a very toxic drug.

Now this is really getting to where we're starting to see a lot more use of immune modulators or monoclonal antibodies. These drugs are being very commonly used to treat a number of different disorders, but lupus and rheumatoid arthritis are certainly big ones. There's little specific data related to breastfeeding, but these medications look to have a very good safety profile. I'm going to talk to her about why I think this is safe, even when we don't have a lot of data. The vast majority of these drugs are going to be L3. There are a few that are L2, but we think that they're safe based on their characteristics. I put all of this information in a table for you to have. You can see there are 3 of them—there are probably 50 different drugs. So I did not include them all. Three of them are L2 just because we have more data related to the relative infant dose. Those are going to be Rituxan, Enbrel, and Humira. The reason that the others are really viewed as L3, even though we don't have any relative infant dose information, is because they are very, very low to no oral absorption, which is the way the baby takes the breast milk. These are injectable drugs because they are enormous. I have the Daltons listed there for all of them, and they are just huge molecules. They should not pass into milk. If they did, they won't be orally available to the baby to absorb because of how big they are. I did also list the target there for you. Even though all of these things are monoclonal antibodies, they're monoclonal antibodies to different targets, and that's going to vary somewhat based on what disease you're treating and which target you're going to be choosing. These drugs are very effective and should be very safe in breastfeeding.

Infections and breast health [00:44:22]

I'm going to move on to maternal infections. Infections—really just a personal perspective. Maternal fever is not an indication for separating the mother and the infant without any consideration to the diagnosis. This is a very frustrating situation. I think it's better now, at least in the US, but I think COVID was very hard on us related to this, where we got very skittish about having mothers and infants together, and that's really super frustrating.

This table goes over all of these things, and you can see that basically they're all safe. Temporary consideration in rare situations, but these are safe. We need to rethink our bent towards separating moms and babies. These are examples of herpes virus on the breast. That ulcer over on the right—thank you to Dr. Smiley for sharing that. That's one of her photos. That's a primary ulcer, so that's very different than a recurrence. A recurrence is going to have that vesicular appearance over on the right side of the screen with the small little vesicles that burst and very different length of duration of that infection. We'll use oral antiviral therapy for this. Depending on the situation, you can consider infant vaccination. You just don't want the baby to have direct contact with the lesions, and you want to talk to the mother about good handwashing. If the lesions are actually in a place where the baby's going to be exposed, such as this picture, then you may want to express and discard the milk on the affected breast if it's going to be in contact with the virus, but the other side would be fine. Then just cover the lesions until they're scabbed over.

The antiviral medications, acyclovir, valacyclovir are safe in lactation. We have good information on these drugs. Chickenpox is airborne transmission or direct contact. The long incubation period is not a problem—it's an advantage. Since the rash happens after you're contagious for a day or two, the horse is already out of the barn by the time that you get the rash. You do want to consider infant immune globulin if it's available to you, if that would be an option for the baby to try to prevent the baby from getting that exposure. If this occurs at birth, you do want to actually separate this baby until the lesions are crusted, because if it's happening at birth, she's got the potential to transfer the virus but not her antibody. If it's later on, she's probably got antibodies. Consider infant vaccination if that's an option. The expressed milk is fine.

Shingles is only transmitted by direct contact, so just cover the lesions unless they're on the breast and would be contaminated by pumping the milk or by direct breastfeeding. Good hygiene is important. Consider the immunoglobulin in the correct scenario or infant vaccination if the baby is older.

TB, a positive PPD is not a reason to separate moms and babies if there isn't any evidence of active disease. No separation and breastfeeding is encouraged. I hear from people that they can't have a PPD during pregnancy and lactation. There is no truth to that. It is fine. If she has active untreated tuberculosis, you would want to separate mother from the baby until she was not contagious. I just don't know how you make this diagnosis without the baby already being exposed. I just can't imagine how that happens, at least in my clinical scenario. I would find out about her tuberculosis a couple of days after her positive test. So if she was isolated and the baby was born and removed at the time of birth, that might be a scenario where this would happen. I think it's very unlikely in that situation. I think most mothers diagnosed with tuberculosis have already exposed their infants.

Hepatitis A is not transmitted in breast milk. It's fine. You can vaccinate if she ate at a restaurant that had a hepatitis A outbreak. You can go ahead and vaccinate her, that's fine. Immunoglobulin is also available, but hepatitis A is not a concern.

Hepatitis B is transmitted from the placenta and breast milk. You manage this though by giving the baby immunoglobulin within 12 hours of birth. It doesn't have to be before skin-to-skin, doesn't have to be before breastfeeding. You can do everything exactly like you usually do, just give the immunoglobulin within 12 hours of birth to protect the baby from any birth exposure from the placenta. The baby's also going to get vaccinated if it's born to a hepatitis B mother. We do that routinely for all babies in the U.S., but for somebody who's positive for hepatitis B, it's most important.

Hepatitis C, they have detected antibody and HCV RNA in the breast milk. This disease is harder to transmit. The data does not really support a difference in transmission rate at a year of life whether or not you're formula-fed or breast milk-fed. There's no reason to avoid breastfeeding with hepatitis C. I would say if she's got bleeding from the nipples—this is really a blood-borne disease. If she's got bleeding from the nipples, I would avoid out of an abundance of caution just feeding on that side. I would have her pump and discard if there was frank blood.

Measles, probably not a problem in Australia. I actually looked at the measles map, and there was no one in Australia. That was fascinating to me because it's been a recent problem for us in the US. It is a not ideal disease in pregnancy. It's highly contagious, and it's highly contagious before the rash by 5 days. It can remain highly contagious for 4 days after the rash. Long incubation period again 6 to 21 days. The neonatal disease, especially in the first few weeks of life, is associated with a fairly large spectrum of disease. We would use post-exposure prophylaxis, just like with chickenpox. Since it's got a long incubation, you can give people the vaccine after they're exposed to prevent them from getting it. We would do that the same if she was exposed to measles outside of pregnancy. We don't give the measles vaccine in pregnancy, but if she was breastfeeding, then we would want to do that. It is quite effective if given within 72 hours of exposure. That will prevent about three-quarters of your measles. If that's not an option, we would use immune globulin, and we would also consider immune globulin for the infant if it was under 5 months of age, or the MMR if the baby is 6 months or older, if we knew mother had an exposure.

Gastroenteritis, you all know that because you're supporting breastfeeding people. It is recommended to continue to breastfeed because that will shorten the incidence and severity of the GI disease.

Bladder infections, I just like to remind people that some of our usual drugs for bladder infections may not be our good first choices in the first month after delivery, just because of the concern over jaundice. Both Bactrim and nitrofurantoin in theory could increase the risk of jaundice in the baby. So those, even though those might be good first choices in somebody who is not breastfeeding, might not be my first choice in a breastfeeding mother if the baby was under a month of age and had jaundice. If the baby is a full-term baby and not really jaundiced, then I'm going to be much less concerned.

The infections are not transmitted in the breast milk. I'm sure you all know that. The concerns would really be related to prematurity in the infant and hyperbilirubinemia. Why this happens—nitrofurantoin actually displaces bilirubin from the albumin binding site. That's the reason that it happens. I like to test my residents on, well, why? That's the reason. For the Bactrim as well, you're going to be cautious with prematurity, G6PD deficiency, and hyperbilirubinemia. Otherwise, these drugs are very safe.

Clinical case studies [00:54:01]

This is a case study for you. This is a patient who is 35 weeks, had a cesarean delivery for twins. She was complicated by diabetes and hypertension with severe features requiring readmission postpartum. She's been pumping and breastfeeding, and at her 6-week visit, she brings in her pump parts because they're pink. She is fine. The babies are fine. She just doesn't understand. These are honestly her pump parts, and we did actually publish this, so you know what this is. This is a rare infection—Serratia marcescens. Serratia produces this prodigiosin, which is a brightly colored pigment. It is a potentially dangerous infection in the NICU. So if it's a premature or debilitated NICU baby, this is a problem. There are outbreaks in nurseries and this can make babies extremely sick. However, these babies were older and healthy, and really this is a concern about where is she getting this contamination and how can we get rid of it in her environment. It is potentially associated with ineffective cleaning techniques for her pump. There are good clinical outcomes outside of the NICU setting or that fragile infant.

I know that you mentioned that you'd already talked about cancer, so the audience is aware, but this is a case study for you. This is a 37-year-old who's 10 months postpartum. She is a pro, she has breastfed all her babies. She knows what she's doing, and she's very comfortable. She comes in because her breast turned red. She has no fever. She has no pain. She just noticed that her breast was red. It's an unusual story. You can see in the picture that that redness is not what we would typically see with a mastitis. We typically would see a red wedge, and this is really very circumferential of the breast where it is entirely red. I've seen that in ladies with very pendulous breasts, where they both do that, but you can compare to the other one. It is clearly just the one breast that is very erythematous. It's actually not cellulitic. It's soft. It feels very much like the other breast, but it is clearly hyperemic. This is actually a case of gestational breast cancer. Oddly, this is not inflammatory breast cancer. This is garden variety intraductal breast cancer—it just happened to cause that hyperemia in her breast in this particular situation.

It is not, however, the first case that I've seen like this. With this particular patient, you can actually see the biopsy site. Since she didn't have those typical mastitis symptoms and it was so unilateral, it just really struck me as incorrect, and we really got her biopsied within the day. She did have adenopathy—again, I didn't notice it on her exam at the time—but she did have adenopathy and some positive nodes at the time of diagnosis. So this was unfortunately a very aggressive disease for her. It did turn out that it's probably a genetically related disease, which may have explained the aggressive nature. I just thought since we had the extra 5 minutes, I would show you that case, even though you talked a bit about gestational breast cancer, just for you all to have it on your radar. Unfortunately, the average age of these women is 32. They are young when they are diagnosed with gestational breast cancer. Just keep it in the back of your mind if it doesn't feel right. The typical characteristics with mastitis is she should feel flu-like and achy and all those things. Just keep that in the back of your mind. Super rare, but just for you all to gain experience from my experience.

Participant Thank you for the opportunity to ask. So I'm doing research on placental anomalies right now to see the impact on breastfeeding outcomes. I also want to see the antenatal development—I mean the breast development—and whether it is affected by the placenta abnormalities. However, it is very difficult to find studies about the placenta anomaly effect on the breast development. I wonder about that. I read your presentation before about the retained placenta where mothers with retained placenta have a high level of progesterone. Is there a cutoff point at which this progesterone level will not affect the secretory activation?

Professor Berens Well, first off, thank you for doing research. This is what we need in lactation. We need more people trying to get scientific evidence to answer these questions. So thank you for doing that. You know, we are actually finding with our Accreta patients that they still seem to have some success breastfeeding when we're purposefully leaving in their placentas. Their progesterones are still falling. It's somewhat interesting to me. I definitely think this is a place that we need more research. Our initial pilot study really looked at initiation, if she did initiate breastfeeding when we left the placenta in. That data was fairly positive. We're working on having a more robust study where we try to get a little bit more detailed information from these mothers. The prior publication that we published on this did not really look at antenatal intent. So I'm trying to add that piece to it. Hopefully the final study will be more robust, but it does take a long time to enroll these patients. We don't have that many—don't get me wrong, because they come to us on purpose to try to keep their uterus. Nonetheless, we don't have a huge amount of data. It's going to take a few years for us to have the final data on that. So thank you so much for doing the research.

Pam We've come to the end of the hour. I would like to thank you, Pamela, for such a rich presentation, a very important presentation for those of us joining you tonight passionate about supporting breastfeeding families. Thank you so much, and also thank you for decades of really profound contributions to the well-being of breastfeeding families and support for those of us who are in the clinic supporting families through all the clinical protocols and the research that you've made available over the years. Thank you very much. You'll be starting your day after such a very early start. I'm just very grateful for your generous willingness to participate today, Pamela. So thank you.

Professor Berens My pleasure, as always. Thank you so much for the invitation, and thanks so much for the interest of those of you in the audience. I really appreciate it.

Pam Thank you, and thank you everyone for showing up.