A year after giving birth, African-American mothers may have more signs of physical and mental stress that can raise the risk of chronic disease, compared with white or Latina women, a small U.S. study suggests.

Researchers focused on cardiometabolic risk factors that over the long-term raise the risk of chronic diseases. These include obesity, high blood pressure, and elevated blood sugar that can temporarily change for the worse during pregnancy, as well as women's levels of the stress hormone cortisol across the day.

While many healthy women return to their pre-pregnancy risk-factor ranges within several months of giving birth, some women remain at increased risk for problems like heart disease and diabetes. 

Socioeconomic Factors

Socioeconomic factors like race, income and education have long been thought to influence women's health after pregnancy. For the current study, researchers followed 2,448 predominantly low-income mothers for one year after childbirth.

They found that African-American women were much more likely to have numerous elevated risk factors one year after giving birth than white women, and Hispanic women had a less pronounced but still increased risk relative to white mothers.

"The experience of poverty, especially urban poverty, has an impact through high, sustained levels of stress, limited resources for good health and unhealthy, if not toxic environmental exposures," said lead study author Dr. Madeleine Shalowitz of the NorthShore University HealthSystem Research Institute in Evanston, Illinois.

"For racial/ethnic minorities, racism and discrimination in all of its forms, is particularly toxic," Shalowitz said by email. "We have more and more evidence that these stresses 'get under the skin' causing the body to make proteins that cause inflammation, and that inflammation causes damage over time."

Most women in the study were overweight or obese and about half had at least one prior pregnancy. African-American women were more likely to have dangerously high blood pressure during pregnancy and less likely to breastfeed. They were also more likely to be single and more likely to be living in poverty.

Latina mothers, however, were more likely to have gestational diabetes and they were more likely to have less than a high school education. White mothers were the least likely to be poor or single and most likely to have a college degree and a spouse.

In the year after pregnancy, risk markers were worst among African American women, but similar between Latina and white women. Black women, for example, had higher body mass, blood pressure, resting pulse rates and less of the natural drop-off in cortisol levels across the day.

The study, online December 18 in the American Journal of Perinatology, wasn't designed to prove whether or how race or ethnicity might influence women's risk factors for chronic disease. It also wasn't designed to show whether any of these risk factors actually caused chronic problems like diabetes or heart disease.