TORONTO, Jan. 12 (UPI) -- A study from Mount Sinai Hospital in Toronto has found that maternal blood pressure before pregnancy could be a predictor of the sex of the baby.
Researchers wanted to determine which factors may influence the chances of having a boy or a girl, so they examined the health of women prior to pregnancy.
Dr. Ravi Retnakaran, an endocrinologist at Mount Sinai Hospital and an investigator with the Lunendfeld-Tanenbaum Research Institute, led a team of researchers starting in February 2009 in studying women in Lluyang, China who were planning a pregnancy in the next year.
The study group consisted of 3,375 women who were planning a pregnancy but were not yet pregnant. Of those women, 1,692 were separated out and assessed for blood pressure, cholesterol, triglycerides, and glucose. Some women were excluded from the study because they were found to already be pregnant.
The group was eventually whittled down to 1,411 women who were assessed at an average of 26.3 weeks before pregnancy.
There were 739 boys and 672 girls born to the women in the study. Researchers adjusted for age, education, smoking, body mass index, waist size, LDL cholesterol, HDL cholesterol, triglycerides and glucose, and found that systolic blood pressure in women before pregnancy was higher for the women who delivered boys.
"[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 press release. "This novel insight may hold implications for both reproductive planning and our understanding of the fundamental mechanisms underlying the sex ratio in humans."
The study was published in the American Journal of Hypertension.