Parents-to-be have been looking for signs that predict the sex of their baby for thousands of years. Carrying high? You’re having a girl! Is your baby bump round like a basketball? Congratulations, you’re having a boy! While these “old wives tales” have never been reliable, scientists can now make an educated guess at about four and half months, during pregnancy, with an ultrasound. Another test, amniocentesis, can be used to check the baby’s chromosomes. This tests is usually reserved for older mothers to identify possible genetic problems.
A new study from China, may offer another alternative for determining the sex of a pre-born baby - tracking the mother’s blood pressure.
Researchers began their study in 2009, with just over 1,400 newly married women in Liuyang, China. All the women had the intention of becoming pregnant within 6 months.
Before becoming pregnant, all the women underwent full lab tests to record their blood pressure, cholesterol, triglycerides and glucose levels.
Once the women became pregnant, their health was tracked. All received routine obstetric care, including continual monitoring of blood pressure shifts, as well as the diagnosis of any complications throughout their pregnancies.
Ultimately, the study participants gave birth to 739 boys and 672 girls.
Researchers found that women who gave birth to boys had registered a higher pre-pregnancy systolic blood pressure (the upper number in a blood pressure reading) than women who gave birth to girls. Mothers of boys averaged about 113 mm Hg, versus mothers of girls who had an average near 110 mm Hg.
After making adjustments for maternal age, educational background, smoking history, obesity and blood labs, they found the blood pressure numbers still held up.
"The only thing that was related was blood pressure, but blood pressure was strongly related," said study co-author Ravi Retnakaran, M.D., an endocrinologist at Mount Sinai Hospital in Toronto.
The findings add another link in the mystery of what determines the sex of a fetus in utero; however, researchers say more studies are needed to prove a mother’s blood pressure determines the sex of her child.
"One of the things we don't want is for people to look at this and think, 'Oh, we can manipulate the blood pressure before pregnancy and thereby change the chances of having a boy or a girl.' We definitely are not saying that, because we are not showing cause and effect," Retnakaran said. "I think the way to look at this is that it may be telling us something very new about [our] physiology."
The study was published in the American Journal of Hypertension.
Story sources: Alan Mozes, http://www.webmd.com/baby/news/20170112/could-moms-pre-pregnancy-blood-pressure-predict-babys-gender#1