Women Who Struggle To Conceive More Likely To Have Sons

Women who take longer to get pregnant are more likely to bear sons than those who conceive quickly, a new study indicates. The chance of a woman having a baby boy was 58% in a group of 500 women who took more than a year to conceive, the Dutch study showed. But among the 4800 women who conceived in less than a year this fell to 51%. For every additional year a couple tries to conceive a baby naturally, there is an almost 4% higher probability of having a baby boy, the researchers calculate. The increased chance remains after allowing for confounding factors such as smoking, alcohol and variability in the menstrual cycle. Epidemiologist Luc Smits of Maastricht University, the Netherlands, who led the study, believes the results support the idea that sperm bearing the male Y chromosome swim faster than sperm with the female X chromosome, and can travel through viscous cervical mucus more easily. He told New Scientist that previous studies have shown that the viscosity of cervical mucus varies between women and that those with more viscous mucus get pregnant less easily.