More girls, less boys
Fertility treatment may produce fewer baby boys.
(Getty Images)
The number of baby boys conceived by a fertility treatment known as ICSI may be lower than what is produced by Mother Nature, a new study suggests.

On average, there are 105 baby boys born for every 100 girls - a natural advantage that helps balance out the higher number of deaths among male fetuses and infants. But in the new study, researchers found that this male-to-female birth ratio seems to be reversed when infants are conceived through intracytoplasmic sperm injection, or ICSI.

Among more than 15,000 US babies born in 2005 via assisted reproduction, the investigators found that a particular ICSI approach appeared to result in a smaller-than-average number of boys.

The effect 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 procedure, just under 50% of births were boys. That compared with a US norm of 52.5% for 2005, according to findings published in the journal Fertility & Sterility.

ICSI involves injecting sperm from the father 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.

ICSI is typically used to treat male fertility problems, such as a low sperm count or poor-quality sperm. 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 full implications of the current findings are not clear, according to the researchers, led by Dr. Barbara Luke of Michigan State University in East Lansing.

About 1% of US births result from all assisted reproductive techniques combined, meaning ICSI accounts for only a small number of births. So it is unlikely that the small effects on male-to-female birth ratio seen in this study would have "any major implications for public health," Luke and her colleagues write.

Still, they conclude, "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."

It is not clear why ICSI might reduce the proportion of male births. However, Luke and her colleagues point out, the study found no evidence that male infertility itself was related to a lower sex ratio - supporting the idea that something about the ICSI process is to blame.

Read Parent24’s Comments Policy publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
Comments have been closed for this article.

Everything from parties to pre-schools in your area.

Jobs - Find your dream job

Reporting Accountant

Cape Town
Network Finance Professional / Prudential
R310 000.00 - R360 000.00 Per Year

Java Developer

Network IT Recruitment
R450 000.00 - R500 000.00 Per Month

Financial Manager

Communicate Recruitment: Finance 3
R750 000.00 - R800 000.00 Per Month

Property - Find a new home