Introduction
There are various reasons why couples may want a child of a particular gender. Certain genetic diseases are only seen in a particular gender. Some couples may have children of a certain gender and may want to balance the family and instead of trying repeatedly and hoping on chance they would prefer a more certain method of selecting the sex more so as economic and population parameters will suggest that families limit the number of children they have. I know a couple with 11 boys and another with 6 boys because they kept trying for a girl. Sex selection can help a couple maximize their chance of having a small family size of both sexes. It is the man, through his sperms who determines the gender of a child. He has two sets of sperms. The Y chromosome-carrying-sperms (the boy sperms) and the X chromosome-carrying-sperms (the girl sperms). The chance of a particular gender being conceived naturally without any intervention is about 50 – 50 though some believe nature slightly favours boys. Historically, unsubstantiated myths exist about how to concieve a particular gender ranging from the position of sexual intercourse to the month the baby is conceived. Nordica Fertility Centre Lagos offers scientific and evidence based sex selection that is backed by results in conjunction with a centre in Europe.

What Is Sex Selection?
These are processes that help to select the gender of your baby.

Reasons For Sex Selection
Medical Reasons: Primarily sex selection should be done for medical reasons. Some countries only allow sex selection for medical reasons. For example there are certain genetic diseases that occur in boys but only carried or transferred by females like Haemophila A and Duchenne’s muscular dystrophy. So a family with a history of these conditions may want to have only female children.

Family Balancing: This is to help a family have children of both sexes. Some families may have all girls or all boys and may want to have the other gender to balance the family. Not all countries allow sex selection on this basis. A school of thought does not agree with this reason for sex selection. 

Sex Selection Techniques
PGD
The best available method scientifically at present for selecting the gender of a child is Pre-implantation Genetic Diagnosis (PGD). In PGD the woman first goes through a process of In Vitro Fertilization (IVF) where her ovaries are stimulated using medications to produce eggs, the eggs are retrieved from her body using a special technique, they are fertilized using her partners sperms and the resulting embryos are biopsied (a small cell is removed from each) and analysed to determine the gender of the particular embryo. The embryos of the desired sex are then transferred into the woman’s womb with the hope they will attach to the uterine lining and grow into a viable pregnancy. PGD is almost 100% certain of selecting the desired sex.

Sperm Sorting/Microsort
In this case the sperms are sorted using fluorescent technology into Y chromosome( boy ) carrying sperms and X chromosome (girl) carrying sperms. The technology is based on the fact that the X chromosome is substantially larger than the Y chromosome. The process uses a fluorescent DNA stain that attaches to the DNA of each sperm and a sorter to identify and separate the sperms. that of a girl is 82%. Not all couples are suitable for microsort. The sperm count of the male partner must be within normal limits (at least 20 million sperms per ml with 50% motility). Sperm samples are collected over a period and banked until a total of about 200 million sperms are collected. They are frozen and sent for sorting. The sorted samples are sent back usually within three to four weeks and depending on the desired gender, the appropriate sperm is used to inseminate the woman or to fertilze her egg during processes of assisted reproduction. Because microsort does not detect the presence of X and Y chromosome directly like with PGD, the chance of achieving the desired sex is not 100%. Chances for a boy is 73 – 81% while that of a girl is 88-92%.

Natural Methods
It is believed that the boy carrying sperms are faster but don’t last as long as the girl carrying sperms which are slower. So if the woman wants a boy she should aim to have sex as close as possible to ovulation as the boy sperm will beat the girl sperm in the race to the egg. If she wants a girl, she needs to have sex two to four days before she ovulates. These methods have not been scientifically proven to work. It was described by Sheetles and he claims a 75% success with this method. This has not been confirmed by other researchers.

The Whelan method partly contradicts the Sheetles method. By this method which believes that by some biochemical changes earlier in the woman’s cycle, the boy sperm is favored at the extreme ends of a woman’s fertile window while a girl more likely close to the ovulation time.

For these methods there are kits that can predict ovulation so these kits help to plan however most researchers have not confirmed that these methods are as effective.

Risks Of The Process Of Sex Selection
In PGD method the embryos may be damaged during testing. The desired sex may not be achieved as all the embryos produced in PGD may be of the sex being selected against. The Microsort method may also result in getting the undesired gender as it is not 100% effective. Because Microsort method is based on separating sperm according to how much DNA is in the sperm, if a sperm with extra or less DNA per chromosome (abnormal sperm) fertilizes an egg, it could cause a failure of pregnancy to occur or a high risk of miscarriage. PGD can along side sex determination also check if the embryos are genetically normal (anueploidy screening) so the chances of an abnormal embryo even if is of the desired gender being transferred into the woman’s womb is reduced significantly by combining sex selection with anueploidy screening in the PGD process.

Conclusion
Sex selection can be done  either for medical reasons or for family balancing. The various scientific methods of sex selection help to significantly improve the chance of couples having a child of the desired gender instead of relying on chance.