Differences between boys and girls show less than 3 weeks into pregnancy.(Brief Article)

2002 APR 18 - (NewsRx.com & NewsRx.net) -- Female embryos exert a greater influence than male embryos over the hormone that nurtures early pregnancy, and the difference can be detected as little as 16 days after conception, according to new research published in the European journal Human Reproduction (Maternal serum HCG is higher in the presence of a female fetus as early as week 3 post-fertilization, 2002;17:485-489).

Israeli scientists have demonstrated that levels of maternal serum HCG (MSHCG) - the hormone that reveals in blood or urine tests whether or not a woman is pregnant - are nearly a fifth higher less than three weeks into pregnancy if a woman is carrying a girl than if she is carrying a boy.

HCG's role at the beginning of pregnancy is to maintain the function of the corpus luteum - a temporary structure formed in the ovary after an egg is shed that produces estrogen and progesterone until the placenta can take over their production.

"Other research has already shown that MSHCG is significantly higher in the presence of a female fetus in the second and third trimesters of pregnancy. But we've discovered that levels were increased as early as 16 days after fertilization," said lead researcher, Dr. Yuval Yaron, director of the prenatal genetic diagnosis unit in the Genetic Institute at Tel Aviv Medical Center.

He said that their finding that MSHCG levels increase with female fetuses before the development of the glands that produce ...