The desire to choose the sex of the unborn child is probably as old as history itself. In many cultures, male offspring are desired to inherit property and carry on the family name. There is a preference of parents to have a son over a daughter in many countries. The preference for sons over daughters can be connected to a number of reasons. In these countries, it is argued that son preference is linked to factors including economics, religion, and culture. In modern times, however, girls are increasingly becoming the preferred sex.
Throughout history, people have tried countless methods for sex selection (Gender selection) but almost none of them have been successful. Sexual positions, timing intercourse according to seasons, trying different food and food preparations are all very unscientific ways for determining the sex of the baby. Some methods might increase the probability of conceiving a certain sex but none is guaranteed to be successful.
The scientific methods used most commonly;
Sperm sorting is an advanced technique that sorts sperm “in vitro” by flow cytometry. This shines a laser at the sperm to distinguish X and Y chromosomes, and can automatically separate the sperm out into different samples. However, a sample that is prepared after the separation technique will not consist entirely of one type of sperm.
Prior to flow cytometric sorting, semen is labeled with a fluorescent dye called Hoechst 33342 which binds to the DNA of each spermatozoon. As the X chromosome is larger (i.e. has more DNA) than the Y chromosome, the “female” (X-chromosome bearing) spermatozoa will absorb a greater amount of dye than its male (Y-chromosome bearing) counterpart. As a consequence, when exposed to UV light during flow cytometry, X spermatozoa fluoresce brighter than Y- spermatozoa. As the spermatozoa pass through the flow cytometer in single file, each spermatozoon is encased by a single droplet of fluid and assigned an electric charge corresponding to its chromosome status (e.g. X-positive charge, Y-negative charge). The stream of X- and Y- droplets is then separated by means of electrostatic deflection and collected into separate collection tubes for subsequent processing. The technology is already in commercial use for animal farming. It is currently being trialed on humans in the US under the trademark MicroSort; it claims a 90% success rate but is still considered experimental by the FDA.
Through Microsort technology one can obtain a sample that contains 88% X bearing sperm or 73% Y bearing sperm. One can use the resulting sample for Artificial Insemination or In Vitro Fertilization (IUI). This results in a 60-70% chance of obtaining a desired gender.
After ovarian stimulation, multiple eggs are removed from the mother. The eggs are fertilized in the laboratory using the father’s sperm in a technique called in vitro fertilization (IVF). “In vitro” is Latin for “within glass”. Fertilized eggs are called embryos. As the embryos develop through mitosis, they are separated by sex. Embryos of the desired gender are implanted back in the mother’s uterus.
Prior to fertilization with IVF, the fertilized eggs can be genetically biopsied with preimplantation genetic diagnosis (PGD) to increase fertilization success. Once an embryo grows to a 6-8 cell size, a small laser incision in the egg membrane (zona pellucida) allows safe removal of one of the cells. Every cell in the embryo contains an identical copy of the genome of the entire person. Removal of one of these cells does not harm the developing embryo. A Geneticist then studies the chromosomes in the extracted cells for genetic defects and for a definite analysis of the embryo’s gender. Embryos of the desired sex and with acceptable genetics are then placed back into the mother. The IVF/PGD technique is favored over the Ericsson method because of the stricter control of the offspring gender in the laboratory. Since only embryos of the desired sex are transferred to the mother, IVF/PGD avoids the small likelihood present in the Ericsson method of an undesired sperm fertilizing the egg. Gender selection success rates for IVF/PGD are very high. The technique is recommended for couples who will not accept a child of the undesired gender.
Embryos can be genetically tested prior to transfer back to the mother. Tests currently used require viable cell DNA which can be obtained from an embryo starting from Day 3. The cells inside an embryo are called blastomeres and there are about 8 blastomeres in a Day 3 embryo. Each of the 8 blastomeres has the potential and genetic material to form a complete human being. As seen in identical twins transferring each of the 8 blastomeres to a separate person can result in 8 babies. Thus one or two blastomeres from a Day 3 embryo can be taken out for genetic testing, this procedure is called Embryo Biopsy. Genetic testing can be performed at an earlier stage embryo by removing and testing the Polar Body. The embryo at its later stages are called Blastocysts and Blastocyst Biopsy can be performed to remove a cluster of cells for genetic testing. Cells removed after the biopsies are tested using the FISH and PCR techniques
Sex selection after implantation can be performed by prenatal sex discernment, followed by sex-selective abortion of any offspring of the unwanted sex. For prenatal sex discernment, a blood test can be taken from the mother for testing of small amounts of fetal DNA within it, and has been estimated to be reliable more than 98% of the time, as long as the samples are taken after the seventh week of pregnancy.
Sex-selective infanticide: Killing children of the unwanted sex. Though illegal in most parts of the world, it is still practiced.
Sex-selective child abandonment: Abandoning children of the unwanted sex. Though illegal in most parts of the world, it is still practiced.
Sex-selective adobtion: Placing children of the unwanted sex up for adoption. Less commonly viewed as a method of social sex selection, adoption affords families that have a gender preference a legal means of choosing offspring of a particular sex.
Social sex selection is officially prohibited in many countries, Turkey included. In nations where gender selection is banned, people often travel to the United States, Mexico, Italy, Thailand and other nations where it’s legal to undergo PGD/PGS.