By Lisa Rapaport

(Reuters Health) – 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 so-called cardiometabolic risk factors that over the long-term cause “wear and tear” on the body and 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 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, a form of the disease that develops during pregnancy, 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 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.

However, some previous research suggests that even when African-American mothers are affluent and well-educated this doesn’t necessarily reduce their risk for pregnancy complications or predict better postpartum cardiometabolic health, said Dr. Kharah Ross of the Alberta Children’s Hospital Research Institute and the University of Calgary in Canada.

“Racism – from blatant person-to-person discrimination to more subtle structural and cultural forms – is a fact of life for African-Americans,” Ross, who wasn’t involved in the study, said by email. “In addition to being a constant stressor (which affects biological wear-and-tear), it also affects access to the resources needed to support health, including health care and information.”

For all women, pre-conception health is key, Ross said.

“Being healthy before a pregnancy helps a woman better weather nine months of physiological stress,” Ross said. “There’s less chance that ‘cracks’ develop because they were shored up or fortified before the stress even began.”

SOURCE: American Journal of Perinatology, online December 14, 2018.