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Do Male Embryos Develop Faster in IVF? – NOW-fertility

NOW-fertility/LinkedIn

Oct 25, 2025, 04:32

Do Male Embryos Develop Faster in IVF? – NOW-fertility

NOW-fertility shared a post on LinkedIn:

“Some recent research has suggested that babies born through IVF may be slightly more likely to be boys than girls.
Dr. Helen O’Neill from University College London shared at the UK’s New Scientist Live event that this might be because male embryos tend to develop a little faster in the lab, therefore when the healthiest-looking embryos are selected for implantation, those that are male are often rated higher quality — simply because they develop a bit quicker.

An embryo’s biological sex is determined by its chromosomes. Male embryos carry one X and one Y chromosome, while females have two X chromosomes. During early development, female embryos inactivate one of their X chromosomes to maintain genetic balance. It is suggested that this extra step may slightly slow down the development of female embryos, leading to male embryos growing a little faster in the early stages.

In a study by Dr O’Neill’s team of 1,300 embryos whose genders were already known through genetic testing, 69% of male embryos were rated as good quality compared to 57% of female embryos.

However, the difference was slight, and if choosing your baby’s gender is important to you—whether for medical or personal reasons—the only reliable way to do so is through pre-implantation genetic testing (PGT) during IVF.

If you would like to know more about IVF with gender selection, please email us at [email protected] or WhatsApp +41 79 884 0734.”

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