The fertility treatment watchdog, the Human Fertilisation and Embryology Authority, has ruled that parents should not be able to choose the sex of their baby unless it is for medical reasons.
The decisions comes after a year-long consultation process.
BBC News Online looks at the issues that were considered
Is sex selection allowed now?
Yes. It is permitted on the grounds of gender-linked diseases, such as haemophilia and muscular dystrophy.
But as technology has improved, the range and effectiveness of techniques for sex selection have increased.
It is possible to select on gender alone, and the HFEA asked for people's views as to whether this should be allowed in the UK.
What did the HFEA do?
It commissioned two independent reports on the range, safety and reliability of techniques available for sex selection and on the social and ethical considerations that related to them.
It also spoke to focus groups, and commissioned an opinion poll.
The HFEA then submitted its findings to the government.
Why do people want to select the sex of their child?
In addition to wanting a child unaffected by a sex related genetic condition, they may want to "balance" a family which already has children of one sex, and have one of the other, or for cultural or financial reasons, such as dowries or inheritance.
How does sex selection work?
There are three main techniques; sperm sorting before conception, preimplantation genetic diagnosis (PGD), carried out before the embryo transferred to the woman, and termination.
Sperm sorting can be carried out either by putting live sperm in a dense liquid and spinning it in a centrifuge to separate sperm carrying the x chromosome and those carrying the y chromosome. Female embryos are xx, and male are xy.
A second method is the Microsort method. It was revealed this week that six UK couples had had healthy babies after having this treatment in the US.
Microsort uses a fluorescent dye which binds to DNA in chromosomes in the semen sample, allowing the sperm to be separated using a laser.
Neither of the methods, which were developed in veterinary medicine, are failsafe.
Some doctors also want to see more research into any health risks which may be associated with sperm selection.
In PGD, a cell is removed from the embryo for genetic testing to detect x or y chromosomes.
It is a more controversial technique than sperm sorting because it involves embryos.
How does the law stand?
Sperm sorting is unregulated and would require a change in the law.
HFEA guidelines allow PGD where there is a significant risk of a serious genetic condition being present in the embryo.
What were the issues about extending availability?
Some believe it is the moral right of individuals to exercise freedom of choice in areas which most closely affect them so long as no one including the child is harmed.
Sex selection is also available in other countries, and the HFEA's current position is being tested in the courts.
But others believe sex selection for social reasons violates divine law, natural justice and the inherent dignity of human beings.
There are also concerns that it could lead to "designer babies" and could lead to unacceptable discrimination between the sexes or families caring for babies of the "'wrong" sex.
What did the consultation process look at?
There were several questions the HFEA asked:
- Should sperm sorting be regulated, and permitted only when it's reliability and absence of health risk have been established?
- Should it be permitted for medical and non-medical reasons?
- Should PGD be used for non-medical reasons or combined with sperm sorting?
- Should sex selection be used for family balancing where there are at least two children of one sex and none of the other sex, or for other reasons?