On average, there are 105 baby boys born for every 100 baby girls. This is a natural condition that helps balance out the higher number of deaths among male fetuses and infants. But in this new study, researchers found that a particular ICSI approach appeared to result in a smaller ratio of male birth.

ICSI is a fertility treatment that involve injecting father’s sperm directly into eggs taken from the mother. If one or more embryos develop over the next few days, they are transferred to the mother's uterus.

This treatment is typically used to treat male fertility problems, such as a poor-quality sperm or low sperm count. However, it is also sometimes used when the cause of a couple's infertility is unclear, and some fertility clinics opt to use ICSI for all patients.

The effect of smaller male birth ratio was seen when ICSI was performed using blastocyst-stage embryos , where embryos are allowed to mature a couple days longer than the traditional norm before they are transferred to the mother. This allows doctors to transfer fewer embryos, reducing the odds of couples having triplets or higher-order births.

Among couples undergoing this fertility treatment procedure, just under 50 percent of births were male. That compared with a U.S. norm of 52.5 percent for 2005, according to findings published in the journal Fertility & Sterility.

Leader of this research, Dr. Barbara Luke of Michigan State University, said, "because our findings suggest that ICSI may reduce the sex ratio, we recommend that ICSI only be done if medically necessary, in an effort to prevent this potential side effect."


Source: Fertility treatment may produce fewer baby boys