A frequently asked question is "Can I choose the gender of my baby using in vitro fertilization?" The answer is, in fact is "Yes." However, there are times when it may make sense and other times when it does not.
In order to be essentially guaranteed of the sex which you prefer to have, the embryos would have to be biopsied. What that means is that a couple undergoes in vitro fertilization, the women has her eggs retrieved, they're fertilized with the sperm, and embryos are created. Typically, on the third or fifth day of embryo life, one cell or multiple cells are extracted from the embryo, and those cells are put in a special culture media. The cells are then transported to a specialized laboratory that will look at the chromosomes of the cell type.
So, for example, you can check for genetic diseases and sex selection. The information that comes back from that specialized laboratory will tell the chromosome nature of the cell and also certain genetic factors like Down syndrome or other types of trisomies and chromosomal aberrations.
The result is generally almost 100% accurate, but small inaccuracies and small errors can exist. The overall chances of having male or female embryos is approximately fifty-fifty, although small differences have been noted in some studies. An embryo that is transferred back into uterus does not always, however, implant. Also, even if you have six or seven embryos, there's no guarantee that normal embryos will be of one particular sex. It's not uncommon to have a case in which a couple asks for a male embryo, and the only ones that are genetically normal are female.
Sex selection is offered for a variety of reasons. Sometimes it's just for family balancing, where a couple has two or three children of one sex and would like to balance their family by having a child of the opposite sex. In many cases it's for genetic diseases, however, in which a particular genetic disease affects only one sex and not the other.
So, sex selection is, in fact, available for couples who would like to do in vitro fertilization. There are some doctors, who, ethically will not do sex selection unless there's a particular disease trying to be excluded. If you are interested in in vitro fertilization and the possibility of sex selection, speak to your reproductive endocrinologist.