The first babies in the UK to be conceived using in vitro maturation (IVM) techniques have been born. The Oxford Fertility Unit - the first clinic in the country to be given a licence to perform the procedure - announced the birth of the twin babies earlier this month.

The Oxford clinic was licensed to offer the treatment in January this year by the Human Fertilisation and Embryology Authority (HFEA). The procedure involves extracting immature eggs from ovarian follicles and maturing them in the laboratory, before returning them to the woman, who is then artificially inseminated in order to fertilise the eggs. The twins - a boy and a girl - were delivered one minute apart and are said to be doing well. The boy, born first, weighed six pounds 11 ounces and his sister weighed in at five pounds 14 ounces. Their parents have not released the children's names in order to protect their privacy.

The benefit of the technique over conventional in vitro fertilisation (IVF) is that women need not take fertility drugs prior to collection of the eggs, making it not only faster and cheaper but also a safer process, as the risk of ovarian hyperstimulation - an excessive ovarian response to the hormones used in IVF which, in extreme cases, can be life-threatening - is avoided. IVM could therefore be an attractive alternative to IVF in particular for women with polycystic ovaries or polycystic ovarian syndrome (PCOS) who may be more at risk of developing ovarian hyperstimulation syndrome during fertility treatment. In addition, it is thought that IVM could also be useful for fertile women undergoing IVF because their partners have impaired sperm.

Currently, IVM has a lower success rate that conventional IVF, but fertility doctors believe that the technique will become better and IVM will become a standard treatment. Only a few centres across the world have the required expertise to be able to mature eggs in vitro and only about 400 babies worldwide have been born following conception after IVM, compared with about two million following IVF.

Earlier this year, the HFEA's Scientific and Clinical Advances Group concluded that no studies on IVM have suggested that the technique is dangerous and that no evidence of abnormalities in the children who have been born following the use of IVM have so far been documented. However, it also said that there is insufficient evidence to be absolutely certain of its safety as the number of children born is very few and those that have been born are still very young and that long-term follow-up studies of the children born following IVM treatment are required to determine if there are any possible effects of using this technique in treatment services. In advising those seeking to apply for a licence, the Authority said that if the technique is offered it should be with all relevant information and prospective parents should be strongly encourage to allow the children born as a result of IVM to take part in long-term follow-up studies.