More Girls Conceived with ICSI

When Mother Nature is left to her own devices, unassisted in the procreation process, we normally see 105 baby boys born for every 100 girls. It’s one of those amazing, naturally occurring course corrections that take place to compensate for the higher number of deaths among male fetuses and infants.

However, when science is invited to participate in conception, specifically through a type of intracytoplasmic sperm injection or ICSI, the boy-to-girl ratio reverses and girls move ahead. The reversal was observed when scientists studied more than 15,000 US babies born in 2005 via ICSI. It is not clear what causes the reversal.

The type of ICSI utilized is blastocyst-stage embryos. Embryos mature about five days longer than the traditional ICSI before they are transferred to the mother for implantation. Many doctors believe waiting for the embryo to mature gives a better chance of finding the best quality embryos with the best chance for development thus keeping overall pregnancy rates high. Because the doctors will transfer fewer embryos, the incidence of multiple births is also reduced.

When couples experienced this procedure, girls were born more than 50% of the time compared with the norm of just over 47%. Full implications of the findings are not clear, according to the researchers led by Dr. Barbara Luke of Michigan State University - East Lansing. The research concludes “because our findings suggest that ICSI may reduce the sex ration, we recommend that ICSI only be done if medically necessary, in an effort to prevent this potential side effect.”

Source: Fertility & Sterility, November 2009.