Age, Ethnicity, and Weight of the Mother Influence Hormone Concentrations During Pregnancy

Hormone levels during early fetal development—which can affect a child’s development and increase the mother’s risk of breast and ovarian cancer years later—are significantly influenced by the mother’s age, body mass index, and ethnicity, rather than lifestyle, according to a study by Rutgers University. The results were published in the Maternal and Child Health Journal.

Investigation of Maternal Hormone Concentrations

The researchers examined the estrogen and testosterone concentrations of 548 healthy women in their first trimester of pregnancy in relation to their lifestyle in order to better understand what leads to elevated sex hormones during fetal development. “Hormones play a critical role in early development for human health and disease risk. Since we cannot directly measure hormones in fetuses during their development, studying the mother’s hormones is the next best method, as they can be transferred to the fetus,” said Emily Barrett, associate professor at the Rutgers School of Public Health and faculty member at the Rutgers Environmental and Occupational Health Sciences Institute. Previous studies have shown that excessive exposure of the fetus to estrogens and androgens, i.e., male sex hormones such as testosterone, may play a role in the later development of reproductive cancers and other conditions such as polycystic ovary syndrome, endometriosis, prostate cancer, and sperm quality in infants.

For the new study, the researchers recruited women in early pregnancy and took blood samples to measure hormone levels. The participants completed questionnaires on demographic data and lifestyle habits, including alcohol and tobacco use and stressors in their lives. Most of the women were white, married, well-educated, and 31 years old on average. Less than 5 percent drank alcohol and less than 8 percent smoked. The researchers found that older mothers and women who had already given birth had lower estrogen and testosterone levels. They also found that overweight women had lower estrogen levels but higher testosterone levels than leaner women. Consistent with previous work, they found that black women had higher testosterone levels than women of other ethnic groups, a difference that may help explain health disparities in reproductive cancers and other hormone-sensitive diseases.

According to the Centers for Disease Control and Prevention, black women and white women are diagnosed with breast cancer at roughly the same rate, but black women are more likely to die from breast cancer than white women. The study found no differences in maternal hormone concentrations related to fetal sex, stressful life events during pregnancy, or lifestyle factors such as smoking and alcohol consumption, suggesting that hormone concentrations were not influenced by maternal behavior or fetal sex. “Determining sex steroid concentrations during pregnancy may provide important insights into the mother’s future disease risk, as high estrogen exposure has been shown to increase the risk of breast and ovarian cancer later in life,” said Barrett, whose research focuses on prenatal exposure to endocrine disruptors, substances that that interfere with normal hormone activity in the body.