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Choosing your baby's gender

Choosing your baby's gender


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The notion that a couple may be able to do certain things to enhance their chances of conceiving either a boy or a girl baby has fascinated the human race for centuries. Ancient and tribal elders, healers and wise men and women have generally been the primary sources of advice, as well as couples passing on their own 'successful' myths and legends.

The history of gender swaying

Methods used for pre-conceptual sex selection have ranged from couples having sex under a full moon, in a certain position or facing a certain direction, or only having sex when the wind blows either north or south, or during a particular season of the year (when it is warm or cold) or even at a certain time of day. In Medieval times, alchemists and herbalists suggested drinking prescribed concoctions just before sex and certain tribes believed in wearing particular garments or trinkets. The Chinese have a lunar calendar based on the woman's age and the month she conceives. This is aimed at providing couples with 'girl' and 'boy' months to either avoid or try to get pregnant. Many astrologists also have theories about sex selection according to certain dates and times in relation to where the planets lie.

It was originally thought that the woman's body was solely responsible for producing either sons or daughters. Of course, over the centuries this perception has caused many women to suffer both physically and emotionally, usually after having daughters because of the importance that many societies place upon sons. However, we now know that it is the man's spermatozoa that determine the sex of each child.

Should we able to 'choose' our baby's gender?

The issue of couples desiring to have a child of a particular sex is a hot, ethical debate. Many believe it should not be something society should encourage (or make widely accessible to people) even if an easy, affordable method was available. Moral concerns lie in creating a gender imbalance similar to what has happened with China's 'one child policy' that has lead to a country with 'too many boys' and too few women for the current maturing generation. However, the other side to this viewpoint is that if a successful pre-conceptual sex selection method was available, then this may help prevent the abortion or infanticide of many female babies in countries where this is a real issue.

The sex 'desirability' of children in countries like Australia, New Zealand, the United States, Canada and the UK tend to be linked more with wanting a child of each sex, or the 'opposite' of a child (or children) already in the family to create 'balance'. However, one concern of sex selection is that couples who have been unsuccessful in their attempts to have either a girl or boy may experience anger, depression or guilt and possibly relationship difficulties with their new child and/or partner, because the baby they conceived is, to some extent, 'unwanted' or 'not right'. What's more, there is the possibility that existing children may feel rejected because they are aware of (also) being the 'unwanted sex'. The bottom line is that you really need to want to have 'a baby' not just a boy or a girl, and be fully prepared if your baby is not the sex you desire.

One medical issue that has driven science towards providing sex selection for couples is to avoid the conception of a child who is likely to have a debilitating sex-linked genetic disorder. This may be the case for couples carrying genes for haemophilia and muscular dystrophy (health conditions that affect only boys). However, the process involved to achieve this is complex and expensive. The couple need to attend a fertility clinic and use invitro fertilisation (IVF) to fertilise several of the woman's eggs. The fertilised embryos are individually tested to identify which ones are 'male' and which ones are 'female'. Then only the 'female' embryos are placed back into the woman's uterus, to hopefully result in a pregnancy of a baby girl. The IVF process in itself affects the likelihood of conception, with only about a 15% success rate.

In Australia, IVF for sex selection is generally only used under these types of circumstances. The idea that IVF be made generally available to couples who simply want a boy or a girl is debatable and regarded as unethical by many. For commercial clinics that do make it available, it is a service that is only within the reach of those who can afford it, without guaranteed success of a viable pregnancy.

X and Y sperm and pH environment

Since the 1950's we have come to learn more and more about the characteristics of a man's sperm and how it may produce either a son or a daughter. We now know that a man's ejaculate of semen contains a mixture of X chromosome sperm (to conceive a girl) and Y chromosome sperm (to conceive a boy). The possible factors that could influence the success of one gender of sperm over the other to fertilise the woman's egg, have become the basis of modern sex selection theories and techniques.

The following are some facts and theories about the possible differences between 'boy' and 'girl' sperm:

  • The Y (or boy) sperm are slightly smaller (carrying about 2.8 to 3% less genetic material) than the X (or girl) sperm. This is a scientific fact. However, this small size difference is not able to be obviously seen under an ordinary microscope. At present, the differences between X and Y sperm can only be made obvious by using a series of involved technical processes using dye staining and ultra violet light exposure.
  • The 'boy sperm' are thought to be faster swimmers than their female counterparts. But 'girl sperm' are thought to be more resilient, having more 'staying power'. This is a theory that has not definitely been proven.
  • Boy sperm are thought to be more fragile and possibly more susceptible to substances that tend to affect a man's fertility (for example smoking, excessive heat, toxins and some drugs). Certain environmental exposures are capable of causing lowered fertility in men. Bearing this in mind, and the fact that 'girl' sperm may be more resilient, a few studies have found that if men are exposed to some 'fertility affecting' substances and do father a child, they are more likely to have a girl.
  • The woman's body may also play a role in sex determination. Both 'girl' and 'boy' sperm require a relatively alkaline environment to survive. This is naturally facilitated by the fluid of the man's semen as well as the fertile vaginal mucous produced by the woman during the days before she ovulates (or releases an egg). However, 'boy' sperm may favour a more alkaline environment than 'girl' sperm. 'Girl' sperm are thought to have the resilience to survive in a slightly more acidic environment. This has not definitely been proven, but is the basis for methods using vaginal douches with sodium bicarbonate solutions.
  • A couple of small studies have looked at dietary changes to influence pre-conceptual sex selection. The ionic balance of a woman's diet for several weeks before conception is supposed to influence the chemical make-up of her egg or her vaginal secretions. Diets high in salt and potassium are supposed to favour boys and diets high in calcium and magnesium are supposed to favour girls.

Methods for pre-conceptual sex selection

There is much information in books and on websites that claim to increase the chances of conceiving a baby of a desired sex. However, many methods are not supported by research or if anything are only based on anecdotal evidence ('after the fact'). Of the few small studies that have been done on the timing of intercourse in relation to when the woman ovulates, the outcomes are conflicting and there is little (if any) research to support some of the more expensive techniques offered by a few commercial fertility clinics. This is where proposed sex selection methods can cause disappointment for many 'hopeful' parents, sometimes at great financial and emotional expense.

The overall statistical chances of a population of people producing sons or daughters are about 49% for girls and 51% for boys. In the long run, this ends up working out to be relatively even, as baby boys are more likely to die during pregnancy or within the first year of life.

Sceptics of sex selection methods say that parents already have about a 50% chance of being successful in having a baby of their desired sex. And as NO sex selection method is 100% effective, if you don't succeed, it can be hard to know whether you are one of the 'suggested' 15 to 20% who have failed in your quest using the technique or in reality, just one of the naturally selected 50% (whether the technique was used or not). However, there will always be people who have used particular sex selection techniques, swearing by them if they have been 'successful'.

The following is a summary of some of the methods and techniques currently offered for pre-conceptual sex selection:


Microsort is a commercial name given to a technique that uses flow cytometry (or FCM) and DNA staining (known as fluorescence in situ hybridization or FISH). This technique was originally used in animals, and has in recent years been used for human reproduction. It involves a fertility clinic taking the man's semen and staining the sperm with a fluorochrome dye. The sperm are then passed along a fine tube, being exposed to ultraviolet light. The process gives the sperm different electromagnetic fields, allowing them to be sorted into X (girl) and Y (boy) groups. The concentration of either X or Y sperm in a group is known as 'enriched' sperm. With about 85% 'girl' sperm in one and about 75% 'boy' sperm in the other.

The disadvantages of this technique are it:

  • Can be a very slow process (only being able to separate 200,000 to 300,000 sperm per hour). This amount may not be enough to allow the enriched sperm to be used for artificial insemination. The separated sperm may need to be injected into a woman's harvested egg using a microscope in a laboratory (a process called intracytoplas micsperm injection or ICSI). This type of IVF technique in itself has only about a 15 to 20% success rate of resulting in a viable pregnancy.
  • May increase the chances of having a boy or a girl, but is not 100%.
  • Is expensive, invasive and requires advanced medical technology.
  • Is still relatively experimental, with concerns about the affects of the dye and ultraviolet light damaging the DNA in the sperm. This has not been confirmed or refuted, with animal studies so far not indicating risks for birth defects or a reduced ability for the sperm to fertilise an egg. The affects on human DNA are less known.


Some commercial fertility clinics use a centrifuge technique (called cytometric separation). The centrifuge is supposed to make the slightly lighter 'boy sperm' rise to the top, leaving the heavier 'girl' sperm to sink to the bottom. This is supposed to separate 'boy' and 'girl' sperm into 2 'enriched' groups (of up to 85% of the desired sex). The enriched sperm is then artificially inseminated into the woman during her fertile phase. However, there is no research evidence to support the success of these claims.

The disadvantages of this technique are:

  • It is expensive and requires artificial insemination (lowering her chances of a successful pregnancy).
  • It has no guarantees and many doctors are skeptical of the claims fertility clinics make about its supposed success. Other clinics who have tried to replicate the procedure to evaluate it have been unable to do so.

Ericsson Method

The Ericsson method is also known as the 'motility technique'. This procedure was patented by a Dr Ronald Ericsson in the early 1980's and is used by a few commercial fertility clinics licensed to do so. The sperm are placed into a sticky, protein solution (called 'albumin'). Theoretically, the 'boy' sperm are supposed to swim down the sorting apparatus quicker than the 'girl' sperm, with the aim of enabling the doctor to create 'enriched sperm' samples of up to 75 to 80% of the desired sex. The 'enriched' samples take about 4 hours to complete, after which the desired sperm are artificially inseminated into the woman during her fertile phase.

The act of patenting the Ericsson method has made it very difficult for other researchers to effectively evaluate the procedure. The reported success of this technique is conflicting and controversial. One report that was aimed at evaluating the Ericsson method, found the clinic was obtaining the opposite results to what they were trying to achieve. The advantage of this method is that it does not harm the sperm.

The disadvantages of this technique are:

  • It involves fees but is not as costly as other medical techniques for sex selection. It requires artificial insemination of the woman (lowering her chances of a successful egnancy).
  • It has no guarantees, with conflicting reports about their claims of success.

Shettle's Method

Dr. Landrum Shettles first published his theories on pre-conceptual sex selection in1970. They are based on the assumed differences between the X (girl) and Y (boy) sperm explained previously in this section. As a brief summary, 'boy' sperm are supposed to be faster but more fragile than 'girl' sperm, which are thought to be more resilient and have more 'staying power'.

Bearing this in mind, the Shettles method believes that the timing of sexual intercourse during the woman's fertile phase is the most crucial element for achieving the conception of a baby of the desired sex. For boys, the method advocates timing sex to be as close to ovulation (or the woman's egg release) as possible, but abstaining from sex for several days before this point in time. For girls, the method recommends timing sex for the 2 to 4 days before ovulation, then abstaining from 1 to 2 days before ovulation until a few days after ovulation. The Shettles method claims an 80% success rate for boys and a 75% success rate for girls. However, the few, small studies done so far have been unable to support these claims.

The advantages of this method are it:

  • Does not cost any money (unless you purchase the book and use ovulation prediction kits).
  • Does not require intervention from a fertility clinic and can be done in the privacy of your own home.
  • Is more likely to result in a successful pregnancy (because it is done naturally), although it does not guarantee a baby of the sex you desire.
  • Does not involve medical interventions that may harm a newly conceived baby.

The disadvantages of this method are it:

  • Requires the woman to track and record her menstrual cycle on a fertility chart using her physical signs (temperature, mucous and cervix changes) to estimate the time of ovulation. This usually needs to be done for a few months prior to attempting to conceive, so she is more aware of when she ovulates.
  • Although it is not regarded as necessary for the technique, some women choose to use ovulation prediction kits to help them more accurately predict when they are ovulating. However, for sex selection purposes these tests must be used twice a day (instead of once per day) and may end up being quite expensive if needed for several months.
  • There is no guarantee it will be successful.

Whelan Method

Elizabeth Whelan published her book on pre-conceptual sex selection in 1977. She based her theory on the biochemical changes that occur earlier in a woman's fertile phase, saying that this is the time that would most favour 'boy' sperm. Her method is virtually the opposite of the Shettles method, advising sexual intercourse about 4 to 6 days before ovulation for a boy and 2 to 3 days before ovulation for a girl. She claims success rates of about 68% for boys and about 56% for girls. Critics of her method say that the 'boy' method may time sex too far away from ovulation to achieve a successful pregnancy for some women (let alone a boy baby).


The idea that changing a woman's diet for several weeks before she conceives (to influence whether she has a boy or girl), originated from German studies in the 1940's looking at the environment that influenced the reproduction of worms. In 1980 a research study was published aimed at testing this theory on determining the sex of babiesin humans. It was thought that through diet, the mineral (or 'ionic') imbalance in the woman's body could facilitate sex selection. The ionic balance was thought to affect the chemical make-up of her egg and/or her vaginal secretions.

The study recruited 281 couples, allocating them into either the 'boy' group, which was a daily diet high in salt (Na+) and potassium (K+) or the 'girl' group, which was a daily diet high in calcium (Ca2+) and magnesium (Mg2+). The women were asked to stay on their allocated diets for at least 4 to 6 weeks before they conceived, for a maximum of 6 months (or until they conceived, whichever came first). The men were also asked to go on the diet, primarily to support the woman, rather than for the purpose of sex selection.

During the study 21 women pulled out, mainly because they could not tolerate their diet or because they conceived before the 4 to 6 weeks had elapsed. Of the 260 women who remained in the study, 80% conceived the child of their choice (Stolkowski and Lorrain, 1980). Proponents of this method often recommend being on the diet for about 3 months before trying to conceive. Some couples will combine this method with the Shettles method.

The advantages of this method are that it:

  • Does not cost any money.
  • Does not require intervention from a fertility clinic and can be done in the privacy of your own home.
  • Does not require the woman to track and record her menstrual cycle on a f ertility chart using her physical signs (temperature, mucous and cervix changes) to estimate the time of ovulation. (Unless she combines her diet with the Shettles method.)
  • The baby is conceived naturally, increasing the chances of achieving a pregnancy.

The disadvantages are:

  • The diet may not be tolerable for many women to stay on, especially for months at a time.
  • The diets themselves may be harmful to your health (for example a diet high in salt). The diet may not be balanced enough to provide much needed vitamins and minerals for a healthy conception and pregnancy. As a general rule, you should not stay on these diets for more than 6 months and as soon as you find out you are pregnant you should return to a more balanced diet.
  • It does not guarantee a baby of the sex you desire.

The boy diet can include - bacon, ham, sausages (and other salty meats), meat, fish (especially if dried and salted), salted chips and nuts, rice, pasta, potatoes, most fresh vegetables, bananas, apricots and most fresh fruits, white bread, pastries, fruit loaf, honey, jam, soups and carbonated drinks.

The girl diet can include - dairy products, yoghurt, ice cream, eggs, mineral waters, fresh fruit juice, rice, pasta, salt-free bread and butter, no salt in foods and only small amounts of fish, meats and fresh vegetables and fruits.


Douching is the use of a liquid to gently 'wash out' the inside of the vagina.The liquid is usually put into a special plastic bag with a tube attached and the end of the tube placed shallowly, just inside the vagina. Gravity is then used to let the fluid slowly flow into the vagina, and slowly flow out again.

The idea of using a douche in relation to conception was first introduced in the 1930's by a German doctor who advised some women with infertility to use a baking soda solution (2 tablespoons in about 1 litre of luke-warm water). This resulted in many of them becoming pregnant, as well as the coincidence that most of their children were boys. His theory became the basis of the theory that 'boy' sperm prefer a more alkaline environment, but these study results have not been supported since.

While douching is a relatively easy method that can be used at home, there is no proof that it works for sex selection. The Shettles method used to include recommendations to douche with a baking soda and water solution for a boy and a weak solution of vinegar or lemon juice and water for a girl, about 15 to 20 minutes before intercourse. However, he no longer recommends this unless directed by your doctor.

The disadvantages of this method are:

  • It is messy and may disturb the normal pH balance of the vagina, leading to infections such as thrush and gardnerella.
  • If the douche is administered with pressure or force (through a bulb or syringe), this may exert too much pressure inside the uterus and could possibly lead to an infection of the uterus and fallopian tubes.
  • There is no guarantee that it works.

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