Pre-Pregnancy Blood Pressure Could Predict Baby's Gender

January 12, 2017
Caitlyn Fitzpatrick

Break out the blue paint for women with higher preconception blood pressure.

Higher maternal blood pressure before getting pregnant? Better start painting the baby’s room blue.

Ravi Retnakaran, MD, MSc, an endocrinologist at Mount Sinai Hospital in Toronto, and colleagues examined the possibility of a mother’s blood pressure impacting the baby’s gender.

This isn’t a completely foreign concept. Previous studies suggested that adverse societal conditions could influence if a fetus is male or female. A study published in the Proceedings of the Royal Society B found that women who consumed more cereal preconception were more likely to have a boy. Although doctors may not be telling their patients to cram in the Frosted Flakes if they’re hoping for a future NFL player, controllable factors’ role in gender continues to be studied.

In this most recent research, the team gathered data from 1,411 newly married women in China. Cardiometabolic characterization included measurement of blood pressure, cholesterol, triglycerides, and glucose. Women who might have been pregnant at the time of assessment were excluded from the study. The heart measures were taken at a median point of 26.3 weeks before pregnancy. The women gave birth to one child at an average of 39 weeks’ gestation.

The deliveries resulted in 739 boys and 672 girls. The researchers adjusted results for age, education, smoking, waist, body mass index (BMI), LDL cholesterol, HDL cholesterol, triglycerides, and glucose.

When all was said and done, women with higher systolic blood pressure before pregnancy (106 vs. 103.3 mm Hg) were more likely to deliver a boy. Lower blood pressure tended to be found in women who delivered a girl.

Retnakaran said that the findings “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.” He stressed that that maternal blood pressure before pregnancy was an independent predictor of baby gender. “This novel insight may hold implications for both reproductive planning and our understanding of the fundamental mechanisms underlying the sex ratio in humans,” he said.

There is already a slight dominance of male deliveries, even though the proportion of fertilizing sperm carrying an X-chromosome and Y-chromosome are similar. But this recent finding adds to the growing evidence on how outside factors contribute to gender.

The study, “Maternal Blood Pressure Before Pregnancy and Sex of the Baby: A Prospective Preconception Cohort Study,” was published in the American Journal of Hypertension. The news release was provided by Oxford University Press.

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