Sex selection of babies in their embryo stage is a controversial topic in many countries. Most of the USA has legalized the gender determination of fetuses for various medical and non-medical reasons. Although some parents choose to keep the sex of their baby a “surprise” till the delivery or C-section, many cannot wait to find out if they are having a boy or a girl. 

However, sex selection is a whole new concept that might sound futuristic to some. Via advanced technologies, it is possible to segregate the sperms that contain the sex-determining factors, aka, the X and Y chromosomes. These new-age methods can define the gender of the fetus with significantly high certainty. 

While Y-linked disorders are always predominant among the male child, X-linked recessive disorders can be tricky to determine without the genetic analysis (amniocentesis) of the fetus. Along with the results, the parent(s) typically receive genetic counseling and the information necessary to take the next step. 

On a more serious note, genetics shows that certain incurable and hereditary diseases or disorders can depend on the biological sex of the child. The presence of either XX or XY sex chromosomes in the karyotype of the fetus or infant can determine their health and wellbeing. Unnatural sex-linked traits or inheritable mutations in the X or Y chromosomes of the parents can determine the child’s predisposition to these sex-linked disorders. 

Methods like pre-conceptual flux cytometry or separation of the sperm by gradients are more effective than the in-vivo natural gender selection methods. The latter includes ways like controlling the diet of the parents before copulation and timing the intercourse correctly according to expert advice. 

Post-fertilization methods are rapidly becoming accessible and safer than before holding the hands of advanced tech. pre-implantation genetic diagnoses (PGD) enables the biopsy of the blastomere. That can ascertain the sex with up to 100% accuracy. It is a method popular among parents trying to avoid X-linked hereditary disorders like hemophilia A, Lesch-Nyhan syndrome, hypophosphatemic rickets, and fragile X syndrome. 

Post-implantation techniques include the determination of fetal sex via ultrasound, amniocentesis, and chorionic villus sampling (CVS). The process of post-implantation sex determination and subsequent fetus abortion has been around since 1970. Although it is controversial, many parents choose to abort a fetus between eight and twenty weeks of gestation if their genetic analysis shows signs of genetic disorders including Duchenne muscular dystrophy, which is more common in males than females. Other sex-linked diseases determining similar decisions among parents include oro-facio-digital syndrome and Rett Syndrome.

Early data from WHO states that as of 2004, January, sperm separation techniques have resulted in the healthy birth of 419 children in the USA. Among them, 91% using X-chromosome enriched sperm were born as female, and 76% using Y-enriched sperm were male.