Tuesday 21/October/2025 – 08:11 AM
A new scientific study has revealed a surprising reason behind the increased probability of conceiving boys through artificial insemination (IVF), as it was found that 56% of children born with this technique are male, compared to approximately 50% in natural pregnancies.
Male embryos grow faster and are more frequently selected for
According to what was published by the British newspaper Daily Mail, scientists explained that male embryos grow slightly faster during the first days of development, which makes them more vulnerable to selection during the process of transferring the embryos to the uterus, which is the stage in which doctors decide which embryos will be implanted.
Dr. Helen O’Neill, a fertility specialist at the University of London, explained that the evaluation tools used in artificial insemination clinics inadvertently contribute to the preference for male embryos. She said: When we link the speed of growth with the quality of the embryo, we tend to choose male embryos. The tools we use by nature choose males.
Artificial intelligence reveals doctors’ bias in selecting embryos
The researchers explained this phenomenon by the genetic difference between male and female fetuses. While male embryos contain an X and a Y chromosome, female embryos have two
The study, which was presented at New Scientist Live and published in the British newspaper i, found that bias towards male embryos occurs during the selection stage, whether by doctors or using some modern artificial intelligence systems that are used to classify the quality of embryos.
Dr. O’Neill’s team conducted an experiment on 1,300 embryos whose sex had been previously determined by genetic testing, and the results showed that doctors classified 69% of male embryos as high-quality, compared to only 57% of female embryos. As for the artificial intelligence systems tested, one showed a slight bias in favor of males, while the other system was more balanced in assessing the genders.
Dr. O’Neill pointed out that the difference in the speed of embryo development is so small that it cannot be used to deliberately determine the sex of the fetus, stressing that choosing the sex of the child is legally prohibited in UK clinics, except in rare medical cases related to genetic diseases that affect only one sex.
She added that these results do not mean that the technology is intentionally biased, but rather that the standards adopted for evaluating embryos make males more likely to be selected, which explains the higher rates of conceiving boys through artificial insemination.
