A study published in the latest issue of the American Journal of Human Biology suggests a new marker: having a mom with wide, round hips. This is a sign of high estrogen concentrations, say researchers at Oregon Health & Science University and England’s University of Southampton, and when female babies are exposed to this estrogen in the womb, they develop an increased vulnerability to breast cancer later in life. Researchers looked at 6,370 women born in Helsinki, Finland between 1934 and 1944 because their mothers’ pelvic bones were measured during routine prenatal care. They found that breast cancer rates were more than three times higher in women with wide-hipped mothers. NEWSWEEK’s Karen Springen talks with study co-author Dr. David J.P. Barker, a medical doctor and epidemiologist at Oregon Health & Science University. Excerpts:
NEWSWEEK: How did you get the idea to look at women’s hip size? Barker: It’s now clear that important diseases, including coronary heart disease and diabetes, originate through development in the womb. What we haven’t yet addressed is whether intrauterine life is importantly linked to cancer. And this paper says, “It sure is.” If your mother’s hormonal profile is linked to you getting cancer, and it is, then it has to begin in the womb. That’s the only time you’re exposed to your mother’s hormones. Particularly it has to be early in the womb because later on, the placenta forms a barrier between you and your mother’s hormones. It’s when the breast stem cells are laid down.
When is that? It’s about eight weeks.
What should wide-hipped women do since they can’t change the size of their bones? What we’ve found is that there’s a vulnerability to breast cancer acquired in embryonic life. If you know people are vulnerable, you can try to protect them. If your mother has broad hips, you may be more vulnerable. It’s like most of the money in breast cancer research is spent looking for genes. The idea is that if you could look for genes, you could start to look for what makes them vulnerable. But known genes explain less than five percent of breast cancer.
Big hips don’t put the mother herself at greater risk? It doesn’t look from the findings in Finland as though it puts you at greater risk. It is a marker of a high estrogen concentration in the blood, which adversely affects the daughter in her embryonic life.
Not the son? We don’t know.
But it’s important for wide-hipped women not to panic. This kind of information is important because it directs scientific attention. We’ve neglected the scientific importance of the embryo. Most cancer research says people must have done something 10 years ago, 20 years ago. These ideas are correct, but they leave a lot unexplained. It may be that we’ve neglected the importance of the embryo. We now know that the human embryo is extremely sensitive to its surroundings.
What other body parts would be markers? Any body part that grows rapidly in girls in puberty is a potential marker. It’s very striking that this marker, across the maximum width of the hips, that is the part that grows faster in girls than in boys. Girls need the space for the time we become pregnant. It might be that soft tissues, like breasts, could be a marker, but we don’t know.
Do wide hips also increase the risk of other estrogen-linked cancers, like ovarian cancer? We’re working on that. It’s a very good question. The answer is not “no.”
Did a family history of breast cancer matter? We don’t know that yet. In Finland, everybody’s sicknesses that lead to hospitalization or to developing cancer goes on a national register. So we know about the lifetime illnesses, and we also can link that to the illnesses in their families.
Would the same results still hold true today, in the United States? There’s no reason why not. The origin of disease in the womb is a universal part of human biology, wherever you live. We’ve always thought there was a link between estrogen and breast cancer. That’s why there’s all the scare about the Pill and hormone-replacement therapy.
Your study found a woman’s vulnerability to breast cancer was greater if the widest distance between the structures at the top of her hip bone was more than 11.8 inches and if these structures were round. Can you tell, just by looking, that a woman has hips this size? With clothes, no. Unclothed yes. We’re talking about mothers who gave birth in Finland 60, 70 years ago. Because so many babies weren’t born because of difficulties coming out of the birth canal, they routinely measured these pelvic bone measurements on women who were pregnant. We’re not talking about exceptionally large women.
Why do we have bigger hips now? Because we’re better nourished. When I first went to China 20 years ago, I was told that if you see a woman with broad hips, she comes from Hong Kong or Taiwan. At that time, nutrition was poor. At that time, there wasn’t enough nutrition around for the hips to broaden.
What are “round” hips? The crest of the hip bone, which you feel above your hip bone on the side, in a woman, it is rounder than in a man. What happens to girls at puberty that distinguishes them from boys is that they broaden their hips, and they also round the crest of the hip.
Can I measure my hips? It’s not a circumference. You could improvise with calipers. Then you could mark off the outermost points of the crest of the hipbone on either side. You can do it with a ruler. You measure the outermost part on the right-hand side and the outermost on the left-hand side.
The big hips are a marker of extra estrogen? Yes. The placenta does not develop until 10 weeks. So for the first 10 weeks of all our lives, we were just bathed in the mother’s fluids.
Maybe some day we will routinely measure moms’ hip bones? Nobody’s ever thought it was important to measure mother’s hormones in the weeks after conception. Now that we know it’s important, we can start sorting it out.
Should everyone be measured? I don’t think that will be necessary. I should think they’d be much more likely to take a blood test to measure hormones in the first months of pregnancy.
Did you stumble onto hip size simply because the measurements were there? Yes. I’m afraid that’s exactly that. It’s just serendipity. We have been doing these studies over 12 years to look at how the size of the baby at birth affects its health, which it does a lot. Just one day we realized that we had all these measurements of the mother, and we got interested in that.
Is there anything else you’d like people to know? The other thing the paper raises is the risk of breast cancer is highest among the women who stayed on in the womb past 40 weeks.
Should women whose pregnancies go past 40 weeks get C-sections? We need more work. It’s too soon to say that. [But] that’s an issue the article definitely raises. The placenta once it’s formed is a barrier between the mother and the baby. It’s a protective barrier. Toward the end of pregnancy, the placenta starts to die. Its barrier function weakens. If you linger on in the womb, you may start to see circulating hormones in the mother’s blood pass across the placenta and go to the baby.
There’s nothing mom can do to shrink her hips or estrogen levels? No. The hip thing is only a marker. It’s like your height. Once you figure out how that is actually linked into hormone levels, there would be a lot of things we could do. We’ve fixed a lot of hormonal diseases. We’ve fixed thyroid disease.
It’s more to identify who we should watch? Yes. It’s about protecting the vulnerable.
