Baby Boys & In Vitro Fertilization (IVF)

In the world of reproductive medicine and family building through IVF (In Vitro Fertilization), there is thought that more male babies are being born. Why exactly is this happening? Scientists are not exactly sure, but researchers have some ideas as to why this might be happening.

Since 1978, over 5 million babies have been born into the world using In Vitro Fertilization technologies. In 2010 there was a study showing that IVF that year had produced 128 boys to every 100 girls. Why might this have happened? If you look at the science, during normal development, female embryos usually shut down the activity of one of their two X chromosomes to keep gene expression levels the same as in male embryos. But this process may be slightly different IVF done in mice studies, and this idea might be behind the gender gap. And although animal studies are very helpful, who is to say the findings translate to the biology of humans, so, more research needs to be done. How might this effect gender and births in the United States, if it is a true trend? If IVF births account for just 1 to 2 percent of total births in the United States, having more males born via fertility treatments such as IVF is unlikely to affect the gender ratio of babies nationwide.

Some couples choose to utilize gender selection during the IVF process for many reasons too – either to balance out their family, gender-wise, or for personal reasons. What is Gender selection? Gender selection is available for patients who wish to select the sex of the embryo used in their fertility treatment. The sex chromosome found in the sperm is the determining factor for gender. Unfortunately, methods to sort X (female) from the Y (male) sperm are still inaccurate due to limitations in current technology. For patients who want to be certain of the gender of their embryo, Preimplantation Genetic Diagnosis (PGD) can be used. This is a more intensive process that involves the examination of embryos during the time when they are developing in the IVF dish. Once the fertilized egg has reached the 5-6th day of development (called a blastocyst) a few cells can be safely removed for testing. If a Y chromosome is present, this indicates that the gender of the embryo is male. This procedure has a 99% accuracy rate for gender selection – significantly higher than with sperm sorting. Couples who want to choose the sex of their child have historically turned to unreliable methods in an attempt to achieve this goal. Popular but unproven approaches typically rely on the theory that Y bearing sperm swims faster or that X bearing sperm is hardier. Currently, preimplantation genetic diagnosis (PGD) is the only proven method of gender selection. This approach involves safely removing cells from a 5 day old embryo during an IVF cycle. PGD sex selection is over 99% accurate. This test leaves the rest of the embryo intact to develop normally.