Fertility specialists have the ability to create and identify embryos of either sex. However, it is illegal to choose your baby's gender in the UK, unless there's a medical reason for it.
You can only legally choose your baby's gender in the UK if you have a serious genetic condition that you risk passing on to your children. Only pre-implantation genetic diagnosis (PGD) has been approved as a technique which does this. So you can't medically intervene with conception just to balance your family, or for social or cultural reasons.
There are some cheap, safe techniques that you can try in the privacy of your own home, though they're pretty unreliable. You could experiment with sex-selection kits or try folklore methods, such as eating more meat if you want a boy.!
What would qualify us for sex selection?
You'll only qualify for pre-implantation genetic diagnosis (PGD) if you have a serious genetic disorder such as haemophilia or cystic fibrosis. PGD reduces the chance of your baby suffering from the same condition, partly by testing for the genes which carry it.
If you think you are eligible for PGD, your case will be decided by the Human Fertilisation and Embryology Authority (HFEA).
PGD is an in vitro fertilisation (IVF) technique. At the fertility clinic, embryos are created from your eggs and your partner's sperm. After these are screened, a specialist will implant two or maybe three embryos in your uterus (womb).
Gender as well as genes can play a part. Duchenne muscular dystrophy, for example, only affects boys. A disease such as haemophilia almost always passes from mum to son. In these circumstances, your doctor would just use a girl embryo. He wouldn't need to test for specific genes as well.
Your clinic will probably offer to freeze any spare embryos. You can then use these if you suffer the distress of a miscarriage, or if you'd like to have more children later on. Using frozen embryos isn't quite as reliable, but it's less invasive, and cheaper than another cycle of IVF.
PGD is expensive, and the NHS has a limit on the number of couples that it can fund. Each IVF cycle costs an average of £5,000, and this doesn't include the bills for consultations, tests and drugs. PGD costs even more than that.
Not all fertility clinics in the UK are licensed to carry out PGD. The HFEA clinic search tool can help you to find a clinic that does.
What is sperm sorting?
This is when doctors try to separate male from female sperm. Sperm sorting is illegal in the UK, but the service is offered, for a considerable fee, in some other countries.
The most-used technique is flow cytometry, which is thought to be about 92 per cent accurate for girls, and 82 per cent for boys.
Flow cytometry works by adding a fluorescent dye to your partner's sperm sample. Experts can then tell male from female by seeing how the dye binds to the genetic material in the sperm.
Once sorted, you can then be implanted with the chosen sperm using relatively cheap intrauterine insemination (IUI).
There's no guarantee of success with sperm-sorting. And IUI is not as effective as in vitro fertilisation (IVF).
Can timing sex decide my baby's gender?
There are two theories about whether this is possible: the Shettles method and the Whelan method, both named after the person that devised them. Bear in mind that these methods are theories rather than proven techniques.
You may decide to try one method if you understand your cycle well enough. But bear in mind that, whichever method you try, you always have a 50:50 chance of conceiving a baby of the gender you'd like.
The Shettles method
This is based on the idea that male sperm move faster, but don't live as long as female sperm. So if you want a boy, you 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 you want a girl, you need to have sex two to four days before you ovulate.
Shettles claims that it's 75 per cent effective for girls and 80 per cent effective for boys.
What is the Whelan method?
The Whelan method partly contradicts the Shettles method. It suggests that biochemical changes earlier on in your cycle favour boy-producing sperm. So if you want a boy, you should have sex four to six days before your basal body temperature goes up, or when your OPK says you are about to ovulate. If you want a girl you should have sex two to three days before you ovulate.
There may be more in this, as experts have found that male sperm have an advantage over female sperm at the very beginning and the end of your fertile window. They also suggest that male sperm can survive longer than female sperm.
How about sex selection kits?
DIY kits which claim to help with sex selection are based on the Shettles theory. Separate girl and boy kits cost about £100. They include instructions, a basal thermometer, ovulation predictor test sticks, supplement tablets, and douches that are supposedly gender specific.
Not surprisingly, the US manufacturer claims a 96 per cent success rate. But some fertility experts say there's not enough evidence to back up these claims.
