Women who start periods early likelier to have girls

NewScientist

01 May 2011
Magazine issue 2810.

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 asked over 10,000 mothers the age at which they had begun their period and the sex of their baby. Forty six per cent of the children born to women who began their periods at age 10 were boys. This figure rose to 50 per cent when the woman began her period at 12, and 53 per cent when the women entered menarche at age 14 (Human Reproduction, DOI: 10.1093/humrep/der107).

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Author: Leslie Carol Botha

Author, publisher, radio talk show host and internationally recognized expert on women's hormone cycles. Social/political activist on Gardasil the HPV vaccine for adolescent girls. Co-author of "Understanding Your Mood, Mind and Hormone Cycle." Honorary advisory board member for the Foundation for the Study of Cycles and member of the Society for Menstrual Cycle Research.