Dr Danie Schneider
Obstetrician and Gynaecologist, Somerset West

Gender selection


The sex of a child depends on whether an ovum is fertilized by an X or a Y carrying sperm. It is therefore the sperm that determines the sex off an offspring as all of a woman’s eggs carry the X chromosome, but sperm carries either an X (girl making) or a Y (boy making) chromosome.

This process can be affected by a variety of factors and therefore attempts to influence it have been practiced as long ago as ancient Greece.

What are reasons for engaging in sex determination or sex selection?

Pure medical reasons would be to prevent the birth of children affected or at risk of X
linked inherited disorders. It is sometimes considered for family balancing reasons where couples
choose to have a child of one sex because they already have one or more children of the other
sex. There are also gender preference reasons that are often in favour of male offspring.
This stems from cultural, social, and economic bias in favour of male children and as a result of
policies requiring couples to limit reproduction to one child, as in China.

What are ethical issues?

Sex selection for non-medical reasons raises serious moral, legal, and social issues. The principal concerns are that the practice of sex selection will distort the natural sex ratio leading to a gender imbalance in society. The fear is also that gender selection could reinforce discriminatory and sexist stereotypes towards women by devaluing females.
Recognizing that there are reasoned differences of opinion, the ASRM Ethics Committee in the USA recently could not reach consensus on whether it is ethical for providers to offer artificial reproductive techniques for sex selection for non-medical purposes. Arguments regarding patient autonomy and reproductive liberty have been offered in support of the practice. Risks and burdens of the procedure, gender bias, sex stereotyping and non-acceptance of offspring, efforts to guard against coercion and issues of justice all raise concerns about the practice.

What are natural gender selection techniques?

The Preconception Sex Selection Diet is based on the theory that a couple can improve their chances of having a female infant by increasing dietary intake of both calcium and magnesium. To improve chances of having a male offspring, dietary intake of sodium and potassium should be increased. Research has not been able to verify these claims.

The Shettles timing method is based on calculating the time of the woman’s ovulation and them trying to conceive either before or during ovulation. It is based on Y-sperm (male producers) swimming faster, but not living as long as the bigger, hardier X-sperm (female producers) and that the vaginal environment is acidic most of the time but becomes slightly more alkaline close to ovulation, which favors Y-sperm. Thus, to conceive a boy, a couple should have sex on the day of ovulation or one day before, and to conceive a girl, they should have sex two to three days before ovulation.

The Shelan-Method advocates the opposite and suggests intercourse four to six days prior to ovulation to increase likelihood of fertilization by male sperm; two to three days before ovulation for a girl.

Research and large population surveys do not support the above hypothesis.

What scientific techniques are available?

Currently, scientific techniques used to select gender have focused on preconception sex selection, which utilizes techniques for sperm separation prior to fertilization, and pre-implantation genetic diagnosis (PGD), which selects the desired sex after fertilization and prior to implantation.

Sperm separation techniques:

The basis of preconception sex selection techniques relies on the ability to separate semen into X-bearing and Y-bearing sperm. Sperm carrying the desired sex would then be used for fertilization via intrauterine insemination or in vitro fertilization. The main advantage of sperm sorting is that creating excess embryos is not required. On the other hand, this group of techniques does not offer very accurate outcomes. Sperm separation techniques are not recommended for sex selection because they have not been found to be as reliable as initially reported. Despite the lack of evidence for these techniques, they are unfortunately still marketed to patients as options by some medical practices.

Post fertilization methods:

Currently, the only reliable techniques for sex selection are limited to post-fertilization methods. The technique of pre-implantation genetic diagnosis (PGD) is employed in assisted reproduction before the transfer of fertilized embryos. In contrast to sperm sorting, PGD provides nearly 100% accuracy for selecting either sex.

What does the law say in SA?

In March 2012, the minister of health passed regulations relating to the National Health Act of 2003. In terms of these regulations, social sexing (determining the sex of the fetus before implantation) is no longer permitted in South Africa.