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In Late Pregnancy Moderate the Intake of Powerful Anti-inflammatory Foods

The right side of the heart pumps deoxygenated blood from the body to the lungs, where it can fill up with oxygen, and then the left side of the heart pumps oxygen-rich blood from the lungs to the rest of the body. So, blood travels from the body to the right side of the heart to the lungs to the left side of the heart and back to the body.

But what happens in the womb? Fetuses’ lungs don’t work because they’re filled with fluid. How does the heart bypass the lungs and spread the oxygen-rich blood coming in through the umbilical cord to the rest of the body? Before we’re born, we have an extra blood vessel—the ductus arteriosus—that directly connects the right side of the heart with the left side of the heart, bypassing the fluid-filled lungs. When the baby is born and takes a first breath, this blood vessel closes. In about 1 in 10,000 births, though, the blood vessel closes prematurely before the baby is born, necessitating an emergency C-section, as I discuss in my video Caution: Anti-inflammatory Foods in the Third Trimester.

Most cases for which there’s a known cause are thought to be related to taking anti-inflammatory drugs such as aspirin or ibuprofen. This is because the way the body keeps this blood vessel open is with a class of inflammatory compounds called prostaglandins. If you take an anti-inflammatory drug, you can undermine your body’s ability to keep it open, and it could constrict closed prematurely. That’s why most authorities recommend that these nonsteroidal anti-inflammatory drugs (NSAIDs) be avoided in the third trimester. The likelihood that anything bad will happen is extremely remote, but it’s better to be safe than sorry.

Sometimes this premature constriction happens even when women are not taking drugs, so-called “idiopathic” cases, which is doctorspeak for “we have no idea what causes it.” If anti-inflammatory drugs can cause it, though, what about anti-inflammatory foods? A few years ago, in my video Chamomile Tea May Not Be Safe During Pregnancy, I profiled two incidents apparently caused by pregnant women drinking chamomile tea. One of which reversed in that the ductus opened right back up once the tea was stopped, but, in the other case, the other baby had to come right out. Since then, there have been other case reports of this occurring––for example, when a woman had been drinking a few ounces of an acai berry drink every day and when another woman had been drinking prune juice and a violet vegetable juice containing a blend of fruits and veggies. Pregnant women should, therefore, take special care when consuming lots of these powerful anti-inflammatory berry nutrients.

What about berries themselves, green tea, and all the other wonderful anti-inflammatory foods and beverages out there? A group of researchers in Brazil compared ultrasounds of the hearts of third-trimester babies whose moms ate a lot of these anti-inflammatory foods with those whose moms ate less, and they could tell a difference. The speed of blood through the ductus in the moms consuming the anti-inflammatory diet was higher, suggesting it was narrower, just like when you pinch the opening of a hose closed and can make water shoot out faster. Also, the right sides of the hearts of the babies whose moms were consuming the anti-inflammatory diet were larger than their left sides, suggesting some blood backup, again an indicator of a tighter ductus. The researchers suggested changes in late pregnancy diets may be warranted, but critics replied that the differences they noted might not have any clinical relevance, meaning it may not matter if the vessel is a little more open or closed. We don’t want to alarm women because many of these anti-inflammatory foods may be beneficial––such as cranberries, for example, which may be useful in preventing urinary tract infections, which can be a risk factor for premature birth. Consuming cranberries is attractive from a public health and cost standpoint if it can prevent some premature births.

Before cutting down on a healthy food such as cranberries, we’d want some stronger evidence that they’re potentially harmful. What about confounding factors? For example, women who ate lots of anti-inflammatory foods might have had other characteristics that could affect fetal blood flow. What we needed was an interventional trial in which pregnant women change their diets and see what happens, but we didn’t have such studies… until now.

A study has shown that cutting back on anti-inflammatory foods such as tea, coffee, dark chocolate, grapes, and citrus for a few weeks during the third trimester did indeed seem to open up the ductus during normal pregnancies. In women whose fetuses had abnormally constricted vessels, a few weeks of eliminating polyphenol-rich foods reversed the ductal constriction in 96% of cases. Importantly, researchers didn’t follow these babies after birth to see if it made any difference. That complete closure only happens in 1 in 10,000 births; we’re not sure what effects relative levels of constriction may have, so it’s too early to be instituting a ban on dark chocolate for pregnant women.

At this stage, what we’re left with is a note of caution. During the rest of your life, I recommend eating healthy foods such as berries and cocoa powder, but from about 28 weeks until birth, pregnant women may want to cut back until we know more.

In Chamomile Tea May Not Be Safe During Pregnancy, I profile those two case reports I mentioned above. As I noted in Anti-inflammatory Antioxidants, highly antioxidant foods are, in general, highly anti-inflammatory foods.

For comparisons between the strength of anti-inflammatory foods and drugs, see Watermelon for Sore Muscle Relief, Anti-inflammatory Life Is a Bowl of Cherries, and Which Spices Fight Inflammation?

The videos provide more information about healthy (and unhealthy) diets in pregnancy:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

20 responses to “In Late Pregnancy Moderate the Intake of Powerful Anti-inflammatory Foods

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  1. What does ‘cutting back’ mean exactly?
    I’m 4 days away from 40 weeks and have been drinking 1-2 black teas, drinking 1 decaf coffee, eating 2-4 table spoons of berries and taking 4g omega 3 (rather than my doctor’s recommended aspirin) every day.
    Should I now be worried?

      1. Just simply because I’m 41. My BMI was 20, I’ve never had high blood pressure. No tests were done (or available)  to see if I needed it. 

        Sent from my Samsung Galaxy smartphone.

    1. Thank you for your question, which is a difficult one as the data are limited. It seems a sensible approach to avoid the foods that have the highest polyphenol content, defined in studies as more than 30mg of polyphenol per 100g of food. This table may beef help to you. The top 52 foods have been considered high levels of polyphenols in one of the studies mentioned by Dr Greger

    2. I should also add that I can not comment on whether you should take aspirin or not in your pregnancy and it may be in your case the beneficial anti-flammatory effect of aspirin outweighs the potential risks.

      1. Yep thanks. I had side-effects to the aspirin which is why I took it upon myself to stop taking it. As I’m 40 weeks tomorrow I would probably have been told to stop it by now anyway. 

        Sent from my Samsung Galaxy smartphone.

  2. Very interesting topic. There may be two sides to the story. If the Ductus remains patent for too long after birth, that can be a problem too. Would completely eliminating the anti-inflammatory foods cause an increased incidence of patent ductus arteriosus? Maybe mon should avoid the foods for most of the third trimester but then start eating them again just before birth to ensure that the ductus closes when it should?

  3. Fascinating article. Human biology is so interesting. I never new how the baby’s circulatory system switched from relying on mom’s oxygenated blood to going it alone. How did those babies figure that out?!

  4. Interesting, in the Chamomile video, one of the references elucidates the mechanism of action of Chamomile by inhibiting iNOS. does this also affect endothelial NO synthase? and if so does this have any implications on patients with CVD drinking Chamomile tea? One would have thought there would be some anecdotal publications as well like the publication on the patent ductus arteriosus.

  5. There may also be a genetic predisposition involved. For example, my family is salycilate sensitive, probably due lower PST enzyme activity resulting in the inability to elimate salycilates as efficiently as other people. Epson salt baths are helpful. If I am eating ‘too healthy’, my ears will ring just as if I had taken too much aspirin. I’m an ethical vegan so I stick to no spice lentils, beans etc versus juices and high salicylate anti-inflammatories such as tumeric.

  6. Is this something that could result in stillbirth or might show up on an autopsy for a stillborn baby? My first child was unexpectedly stillborn at 40+ weeks. They ruled “cord compression” but there were no knots or kinks visible so more of a process of elimination ruling than anything else. The pregnancy was extremely healthy up until then and I did and do eat a plant based and high anti-inflammatory diet.

    So grateful for the work you put out there. I was turned on to your work while taking the Cornell Plant Based Nutrition course and have been a huge fan ever since. I work as a fitness trainer and recommend this site to all my clients!

  7. I’d be really interested in a video or article regarding inflammation / Maternal IL-6 and mental health, especially in light of the concerns above regarding anti-inflammatory foods.

    “Maternal IL-6 during pregnancy can be estimated from newborn brain connectivity and predicts future working memory in offspring”

  8. What about taking baby aspirin (81mg of aspirin) throughout pregnancy to prevent the onset of preeclampsia. Doctors and midwives claim that there is evidence that taking it every day from 12 weeks to end of pregnancy is essential to prevent preeclampsia.

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