Pregnancy tips If It Takes A Long Time To Get Pregnant, Boys More Likely

I've known a number of women who had boys after a long struggle to get pregnant. Here's an article that may explain why:

Patterns: If It Takes a Long Time, It May Be a Boy
By Nicholas Bakalar (www.boston.com)


From the article:

An investigation of 5,283 Dutch women revealed that 57.6 percent of those who took longer than 12 months to become pregnant had boys, compared with 51.1 percent boys among those who became pregnant in less than a year.

Although human semen has equal numbers of Y-bearing male sperm and X-bearing female sperm, the males may be better swimmers in viscous cervical mucus, the authors speculate. That mucus makes impregnation more difficult.

"The best-supported hypothesis," said Dr. Luc J. M. Smits, the lead author, "is that the Y chromosome is lighter than the X chromosome, while Y- and X-bearing sperms have the same locomotive power. In liquid fluids, this difference would not cause differential speed, but in viscous fluids it would." Dr. Smits is a lecturer in epidemiology at the University of Maastricht in the Netherlands.