Does Age at First Menstruation Predict Your Child’s Sex?

A new study contends that when a woman begins menstruating may effect what sex of child she eventually gives birth to.

Did you start your period at a very young age, or were you much further into your teens?  The answer to that question may help you predict if you are more likely to have a boy or a girl if you eventually have children.

Via New Scientist:

WILL a baby be a boy or a girl? If the mother started her period at a young age, it is more likely to be a girl.

That’s according to Misao Fukuda at the M&K Health Institute in Hyogo, Japan, and colleagues, who found subtle differences in sex ratios of children depending on when a mother entered menarche.

Fukuda points to previous research demonstrating higher levels of the female sex hormone oestradiol in women who entered menarche before the age of 12. This may lead to spontaneous miscarriage of fertilised male eggs, he says. The theory is plausible, says Valerie Grant at the University of Auckland, New Zealand, as male embryos are known to be more vulnerable to hormone imbalances.

The difference in number of each sex is only a few percent every few years, with only a total of 7 points difference between a first period at age 10 and one at age 14.  At the age of 12, there appears to be a perfect 50/50 balance.

(Via Jezabel)