Does childbearing increase a woman’s risk of developing cardiovascular disease later in life?

That is the question second-year USF College of Public Health PhD student Zailing Xing highlighted in her poster, “Parity and Risk of Cardiovascular Disease in Women Over 45 Years in the United States: NHANES 2007-2018,” at this year’s USF Health Research Day.

Xing, who holds a master’s degree in epidemiology from Peking Union Medical College in China, analyzed data from the National Health and Nutritional Health Examination (NHANES) from 2007–2018 to examine whether having children impacts the development of cardiovascular disease in women ages 45 and older in the United States.  

NHANES is a major program of the National Center for Health Statistics (NCHS). NCHS is part of the Centers for Disease Control and Prevention (CDC) and has the responsibility for producing vital and health statistics for the U.S.

“Most countries around the world face the harsh reality of significantly dropping fertility rates and declining willingness to bear children,” said Xing, who is earning her PhD in epidemiology.

She says that among women in the U.S. of childbearing age (ages 15 to 44), the birth rate has dropped from 70 percent in 2007 to 55.8 percent in 2020.

“That’s a drop of about 20 percent in 13 years,” Xing said.

An area that deserved more attention, according to Xing, was whether giving birth influenced the development of cardiovascular disease later in life, and if the number of children influenced those outcomes as well.

In reviewing the data, she found that the prevalence of cardiovascular disease was the lowest in nulliparous women (those who have birthed no children) over the age of 45. She also found that having three live births demonstrated slightly lower risk for women. 

“Specifically, after adjusting for demographic factors, cardiovascular disease risk factors, and reproductive factors, the odds ratio of cardiovascular disease with having live births of 1, 2, 3, 4, 5+ were 1.95 (95% CI:1.23-3.09), 1.94 (95% CI:1.30-2.89), 1.63 (95% CI:1.07-2.47), 2.08 (95% CI:1.32-3.28) and 2.06 (95% CI:1.31-3.24), respectively, compared to nulliparous women,” Xing said.

She says these results imply that parity (the number of births a women experiences) is significantly associated with maternal cardiovascular disease risk.

Xing, who is also an active member of the Maternal and Child Health Student Organization, said that while further studies are needed to confirm these findings, this research could be a starting point for providing some more insight on the impact of pregnancy on health outcomes for women in later life.

“I hope my research results can provide scientific evidence to protect women’s health,” she said. “Next, I plan to further explore the interaction of parity and age at live births on women’s health in later life using more national representative longitudinal data with causal inference approach. My doctoral dissertation will focus on the implication of parity, age at first live birth and age at last live birth on all-cause, CVD-cause and cancer-cause as well as  life span among women over 45 years in the U.S.”

Xing, who said she hopes to continue to engage in the field of maternal and child health via national and international organizations, says she submitted the manuscript for this research to the Journal of Women’s Health in February.

Story by Anna Mayor, USF College of Public Health