Angela Martini surprised everyone when she discovered in early December that she had become the mother of a son, Kyree, who was born to a surrogate mother . In a recent interview for the Swiss newspaper Blick , the model revealed some details about the special pregnancy.

"For many personal reasons, we decided that our child would be born to a surrogate mother," Angela said. "I know how unusual such a procedure is in Europe in terms of law and culture."

Martini said that thanks to the development of science, she and her partner, Drago Savulescu, were able to choose the gender of the child. How is it possible?

The procedure is known as sex selection and is done during in vitro fertilization (IVF). Chrissy Teigen also revealed five years ago that she chose to have a daughter when she underwent in vitro fertilization. IVF is the process where an egg is removed from a woman's body and fertilized by sperm in a laboratory to create an embryo. Thanks to IVF, parents theoretically have the opportunity to "choose" the sex of the baby, although in fact it is a complex process.

Before an embryo is implanted in the uterus (whether that of a biological mother or a surrogate mother), most fertility clinics perform genetic testing of the paraimplant to see if there are any serious or fatal genetic disorders. This examination makes a detailed observation of the composition of the embryo chromosomes to determine if it is healthy enough for further stages. As part of this examination, doctors are also able to identify the sex of the embryo (s).

However, doctors point out that parents can be able to choose the sex of the baby only if they are two embryos (ie girl and boy) equally healthy. Most fertility doctors will encourage parents to select the highest quality embryos, regardless of gender.

Is it a good idea or a bad one? There are different opinions. Some critics worry about possible bias in choosing gender, while others believe it is a personal decision that belongs to the parents.