For more than 30 years, Michele Forman has been studying women's health, with an emphasis on the effect of pregnancy, early childhood, puberty and the reproductive years on the risk of breast and other hormonal cancers. Currently, she's the principal investigator for the Harris County and Travis County sites of the National Children's Study, which is the largest longitudinal study of children's development ever undertaken. It will follow 100,000 children (and their parents) from conception to age 21.
I recently sat down with Forman, the Bruton Professor of Nutritional Sciences at The University of Texas at Austin, and asked her to draw on her deep knowledge of women's health to offer practical advice for pregnant women.
What do you mean when you say that pregnancy is a great twofer? Is that a scientific term?
Forman: It's a time when, by making healthy changes in your lifestyle, you can improve both your own health and the long-term health of your unborn child. That's what I mean by it being a twofer.
Give me an example.
One great example is the benefit of moderate physical activity. Just go out and walk a few times a week. Moderate walking is associated with a range of long-term health benefits for the walker, including reduced risk of breast cancer.
There's evidence, as well, that moderate physical activity during the mother's pregnancy can delay the onset of menarche in girls. Harvard has been conducting an incredible longitudinal study that's been tracking the health of more than 100,000 female nurses over three decades. We did a study in which we went to some of these women and were able to find out whether their mothers had been physically active during their pregnancies, and to correlate the level of activity in pregnancy with the age of menarche in the nurses. We found that the age was three months later on average in the women whose mothers were active compared to those whose mothers were inactive during pregnancy.
That's rather astronomical. The average age of menarche has been going down for more than a century. Three months is the equivalent of turning the clock back 40 years.
How does that delay benefit the children?
It effectively reduces the cumulative exposure over the life course to hormones and reduces the risk of breast cancer. It's a huge benefit. Get out and walk. Swim. Do what you can do. You don't have to overextend yourself, and in fact shouldn't. You'll be healthier, and your baby will be healthier.
What are some other twofers?
Don't drink. Don't smoke. Don't overeat. Excessive drinking, smoking and overeating are never a good idea, of course, but think of pregnancy as an opportunity to make changes in these habits for the sake not just of your own health but the health of your baby as well.
What about taking prenatal vitamins? Is that a twofer.
No and yes. Before they're pregnant most women are probably getting sufficient vitamins and nutrients without supplementing, so no in the sense that it's not an intervention that is improving the mother's baseline health. But yes in the sense that if you don't start taking prenatals once you're pregnant, you may fall below that baseline, since the baby is going to get first dibs on a lot of essential vitamins and nutrients. And if the mother starts suffering from deficiencies, then that puts the baby at risk as well.
It's fairly common in the developing world, for instance, for pregnant women to develop night blindness because their babies are getting most of their vitamin A. We don't have to worry about vitamin A deficiency so much in the U.S., but pregnancy-induced anemia, for instance, is very common. The baby's getting your iron first, and anemia during pregnancy can increase the risk of preterm birth and low birth weight.
You have to remember, once you're pregnant, that everything you do is for two of you. That's true for your diet in general. It's part of why prenatals are so important.
Are prenatals important for the development of the baby, apart from making sure the mother is healthy?
Absolutely. The omega-3 fatty acid DHA, for instance, which you can get from fish oil. It's not something you necessarily need for your own sake, but it's believed that it may help in the development of the baby's brain. Folic acid is another one. It plays a key role in bringing down the rates of neural tube defects like spina bifida.
Can there be too much of a good thing, in terms of vitamins and supplements?
Yes. We have evidence that women who take too much folic acid have methylation patterns in the core blood of their offspring similar to those of women who take none. Women need to be aware that the amount under the current guidelines is sufficient. You don't need to take any more, and in fact you shouldn't. More is not better. These methylation patterns are associated with obesity in the child later on.
There's evidence that a similar dynamic may be the case with vitamin A as well. So you have to be careful.
So does that mean women should trust their prenatal vitamins?
Not entirely. They should know that the recommended guidelines are a good place to start. But the actual vitamins and supplements you can buy over the counter are very lightly regulated by the FDA. The fact is that there are hundreds, maybe even thousands, of prenatal vitamins out there on the shelves, with a lot of different amounts and ingredients of different things. And not only is there a great deal we don't know about the effects of a lot of these ingredients on the mother or the child, in some cases you can't even tell from the label what some of the ingredients are.
Really? What do you mean?
We're in the process of creating the first comprehensive database of prenatal vitamins and supplements on the market. One of the ingredients we've noticed, as we go about assembling the database, is something that's identified on the label as an "antioxidant compound." Unless you go to the database that pharmacists use, there's no way to figure out what that compound is. And even then, once you've learned, say, that it's an extract from blueberries, we don't know what the effect of that is on the mother and child.
In many respects it's a free-for-all right now in terms of what's in prenatal vitamins and supplements. We're creating this database. We're trying to keep up with the new products that are coming out. We're hoping to integrate information about prenatals into the National Children's Study, and then ideally over the next few decades we can begin to really learn what the effects of all these things are. But for now, don't trust your prenatals, particularly if they have ingredients that you don't understand. Trust your obstetrician. Talk to them about which vitamins you should be taking.
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