Mother’s blood pressure could affect sex of her baby, study suggests

Blood pressure affects many functions in the body—and a new study has just discovered another one, one that could determine the sex of a child.

The study, published in the American Journal of Hypertension, suggests that a woman’s blood pressure before she gets pregnant could determine her likelihood of have a boy or girl. Ravi Retnakaran, MD, an endocrinologist at Mount Sinai Hospital in Toronto, led the study, which began in 2009.

Retnakaran and his team established a pre-conception cohort that included young women who were planning to get pregnant in the near future. The women underwent baseline medical assessments and the researchers then examined the relationship between a woman’s pre-pregnancy health and the sex of their baby.

The cohort included more than 1,400 women who were assessed at about 26 weeks before pregnancy. Their pregnancies result in 739 boys and 672 girls. Results showed that women with higher systolic blood pressure before pregnancy were more likely to have a boy than those who delivered a girl.

“[This] suggests that a woman's blood pressure before pregnancy is a previously unrecognized factor that is associated with her likelihood of delivering a boy or a girl,” Retnakaran said in a statement. “This novel insight may hold implications for both reproductive planning and our understanding of the fundamental mechanisms underlying the sex ratio in humans."