Sex Selection

The reliable scientific way to choose a baby's sex is ICSI with preimplantation genetic testing (PGT). The sex of each embryo is read from its sex chromosomes: XX for a girl and XY for a boy, and an embryo of the chosen sex is transferred to the uterus.

How is it done?

1. Ovarian stimulation and egg retrieval, as in ICSI.
2. Injecting the eggs and culturing the embryos to day 5.
3. A small biopsy from the outer layer of each embryo.
4. Chromosome analysis with next-generation sequencing (NGS), which also detects an abnormal number of chromosomes.
5. Transfer of a healthy embryo of the chosen sex in a later cycle.

Medical reasons for sex selection

Some genetic diseases mainly affect boys because they are linked to the X chromosome, such as hemophilia and Duchenne muscular dystrophy. In these cases, choosing the embryo's sex helps avoid passing on the disease.

What to know

• Sex is identified very accurately, because it is read from the chromosomes themselves, but a pregnancy is not guaranteed.
• The result depends on the number of healthy embryos: there may not be a healthy embryo of the chosen sex in every attempt, and more than one cycle may be needed.
• Other popular methods, such as special diets or timing intercourse, have not been shown to determine the baby's sex.
• The decision is discussed with the doctor, including its medical and ethical sides, before starting.