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Choosing the baby's sex

Published:Sunday | February 7, 2010 | 12:00 AM

Heather Little-White, PhD, Contributor

Couples who want a family will make efforts to have children. Mother and father usually have gender preferences for each child. Determining the gender of a baby is not something that can be easily arranged. There are several methods and myths that have been used to determine the gender of babies.

It is important to have an understanding of the role of the bodies of men and women in making babies. With women, the process begins in the ovaries, with ovulation, where as eggs mature, the ripest one travels down the fallopian tube and should be fertilised within 12-24 hours after release once the sperm meets upon an egg. If the egg is not fertilised, it ends its journey at the uterus and disintegrates, resulting in the monthly period.

Sperm production

Millions of sperm are constantly being produced.The average sperm lives only a few weeks in a man's body and as many as 300 million are released with each ejaculation, so men constantly make sperm in their adult lives. Sperm production begins in the testicles and it is stored in the epididymis until it is mixed with semen just before ejaculation. Since only one sperm can fertilise each egg, the baby's gender will depend on which type of sperm (X or Y) reaches the egg first to fertilise it.

Shettles method

For years, several couples have used the non-invasive Shettles method to choose the sex of their children. The Shettles method, developed by Dr Landrum Shettles and David Rorvik, authors of How to Choose the Sex of Your Baby, gives couples at least a 75 per cent chance of conceiving a baby of the gender of their choosing. The principle of this method is that the Y chromosomes for boys move faster but do not last as long as X chromosomes for girls.

The science behind the sex of the baby is determined by which sex chromosome fertilises the egg first. Y chromosome represents a male and X represents a female. It is important to know the characteristics of each chromosome.

Wanting a boy

For a boy, sperm with the Y chromosome should be deposited as close as possible to the egg because the Y chromosome has a short lifespan and it will not live longer than 24 hours, compared with the sperm with the Y chromosome which will live in a woman's body for up to 72 hours. To get the sperm deposited close to the egg, the man must use deep penetration in the missionary position because the Y chromosome must reach the egg first because of its short lifespan. What is helpful to having the Y chromosome fertilise the egg for the making of a boy is for the woman to lift both her legs as close as possible her breasts during ejaculation.

It is also recommended that if a couple wants to have a boy, the man should not ejaculate four to five days before the woman ovulates. This allows for a build-up in the amount of sperm carrying the male chromosome. Eventually, when the ejaculate is deposited in the vagina, it increases the chances of the sperm with Y chromosomes reaching the egg first.


If a woman achieves an orgasm during intercourse, the wavelike contractions of the orgasm will help to increase the speed at which the sperm moves along the fallopian tubes towards the egg in the cervix. Orgasms also reduce the pH levels in the area around the cervix, which, if too acidic, can be dangerous to the male gene. Closely related to pH levels in the vagina and the life of the sperm with the Y chromosome is diet, which influences the acid or alkaline levels of the vagina and the area around the cervix. A woman should alter her diet to include foods high in sodium and potassium. If she is hypertensive, she should check with her doctor. These foods will help to create a more alkaline environment for sperm carrying the male gene allowing them to live longer, increasing their chances of reaching the egg first.

Wanting a girl

For a girl, sperm should be deposited as far as possible from the egg. Sperm with the X chromosome are slower swimmers and will take their time to reach the egg. Besides, sperm with the X chromosome live longer. This requires shallow penetration during sexual intercourse, achieved through rear-entry positions such as the doggie style.

Timing ovulation

Timing is a critical factor in gender selection. Since sperm with the male chromosome have a short lifespan, if couples want a boy, they should have intercourse as near to ovulation as possible. Ovulation prediction kits are available to help determine ideal timing for sex.

If sex takes place too early before ovulation, sperm with the Y chromosome will die before the egg is

released. Longer-lasting sperm with the X chromosome will be ready for fertilisation to produce a girl when ovulation takes place. The time of ovulation depends on the length of the menstrual cycle. In an average 28-day cycle, ovulation may most likely occur between the 12th and the 15th day. The ripening of the eggs, and ovulation, are also influenced by several hormones.


The Ericsson method is used by fertility centres in the United States. Dr Ronald Ericsson devised a method in which the X and Y sperm are separated and used for insemination of the female when ovulation is expected and are then available to fertilise the egg.

Billings method

The Billings fertility method is a daily record of evening observations of the vulva and cervix to record changes in the mucus in the cervix related to ovulation and distinct from secretions from intercourse. The information will indicate when ovulation takes place so timing sex can be arranged.

According to Anak Inya, writing for Ezine, sexual positions have been one of the easiest and tested ways to influence the gender of your baby. While there is not much evidence that any particular position is more likely to lead to conception, it has been posited that positions that deposit sperm closest to the cervix are more promising than other positions.

Have fun!

Couples should have fun during sex and engage in it frequently enough for live sperm to be in a woman's reproductive tract during ovulation. Couples should relax after the fulfilment of joyful sex and the woman should remain in a horizontal position, lying on her back for 15 to 26 minutes, so gravity can help sperm to swim towards an egg (

Whether it is scientific evidence or old wives' tales, women will continue to exchange ideas about increasing the chances of having a boy or girl and embark on practising the strategies with the hope of getting the gender of choice.