Is dark chocolate healthy for mom and baby during pregnancy?

I was taken a little aback when I read these headlines in February 2016: “Pregnant women rejoice! Chocolate during pregnancy has awesome health benefits,” and “Daily chocolate during pregnancy helps mom and baby.”

They were referring to a study presented at the Society for Maternal-Fetal Medicine’s annual meeting that looked at the effects of daily chocolate intake during pregnancy. While these headlines appeared to be cause for celebration, it’s important to pause and look a little more closely at the study’s details – which didn’t receive as much attention in the press. Specifically, I was concerned about when in pregnancy these women were given chocolate.

About the same time this study was being presented, my pediatric cardiology colleagues and I were treating a patient in her third trimester whose baby we suspected had prenatal constriction of the fetal ductus arteriosus, in which a blood vessel that connects the right side of the heart to the aorta in a fetus begins to close prematurely.

In looking at a possible cause, we made sure the patient wasn’t taking any medications that could trigger this. Then a cardiologist asked about her diet, specifically foods high in flavonoids – grape juice, red wine, and chocolate! She shared a study with us that looked at the association of these substances and changes in blood flow in the ductus arteriosus.

So here we were worried about a possible negative side effect of chocolate consumption late in pregnancy while a highly publicized study was touting possible benefits early in pregnancy!

Women often want to know what not to eat while pregnant. We warn them to avoid foods such as soft cheeses, uncooked seafood, and alcohol, but we don’t want to deprive you of everything you love! So, is dark chocolate safe for you and your baby during pregnancy? Let’s take a look.

Studying the possible benefits of dark chocolate early in pregnancy

Chocolate – particularly dark chocolate – contains flavonoids, a naturally occurring compound that is part of the polyphenol family, which is rich in antioxidants. Many foods contain flavonoids, including vegetables, berries, red wine, and green tea, and some research suggests they may lower your risk for heart disease, diabetes, cancer, and other common diseases. Flavonoids also may improve vasodilation, or widening of the blood vessels, thus improving blood pressure.

This recent study of chocolate and pregnant women tried to determine whether flavonoids might have an effect on women’s blood pressure or fetal growth. They split women into two groups and had them eat a small amount of chocolate daily – one group eating chocolate with a high flavonoid content and the other eating chocolate with a low flavonoid content.

While they didn’t find any benefits on blood pressure, the size of the placenta, or the baby’s birthweight, both groups did show some improvement in blood flow to the uterine arteries. That blood flow helps the placenta develop and function normally, leading to good pregnancy outcomes.

This study did not examine whether chocolate itself was good for pregnant women and their babies. It looked specifically to see whether there were any differences in outcomes of the two groups of women – those who ate high levels of flavonoids compared to those who ate less flavonoids. There was no control group of women who didn’t eat chocolate.

It’s also important to note that these women were eating this chocolate during the late first trimester to the end of the second trimester. The study did not require the women to eat chocolate in the third trimester.

Possible negative effects of dark chocolate during the third trimester

The ductus arteriosus is a blood vessel that allows oxygen-rich blood from the right ventricle of the heart to bypass the fetal lungs – which aren’t needed to deliver oxygen because the umbilical cord supplies oxygenated blood to the baby from the placenta.

After birth, that blood vessel closes and blood flows to the lungs. However, we don’t want it to constrict or close before the baby is born because it can cause pulmonary hypertension and the right side of the heart to function abnormally.

We’ve known for a long time that nonsteroidal anti-inflammatory drugs such as aspirin or ibuprofen can cause this condition, and we caution pregnant women not to take them, especially in the third trimester. But we’ve also discovered that dietary sources also may trigger fetal ductus arteriosus constriction – specifically foods rich in polyphenols.

We do know that reducing intake of these foods may lead to a reversal of the condition, which is why the cardiologist was asking my patient about the type of foods she ate. And this might be a reason for your doctor to suggest you cut back or stop eating certain foods during your third trimester.

Should I eat chocolate during pregnancy?

Early in your pregnancy, we’re not concerned about you eating a little chocolate now and then. And as the results of this recent study suggest, there may be some benefits to uterine artery blood flow. When you get to your third trimester, talk to your physician about whether you should scale back your chocolate consumption or find an alternative to your green tea.

As with many things, moderation is key. Chocolate doesn’t have much nutritional value, so you never want to go overboard with it. Make it an occasional treat, not part of your regular diet.

And the next time you read a headline about a health study that sounds too good to be true, take a closer look and talk to your physician.

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