Two studies have provided an insight into the health implications of using assisted reproductive technologies (ARTs). The first finds that twins conceived by ART are more likely to be born preterm, be of low birthweight and to be 60 per cent more likely to be admitted into neonatal intensive care. The second finds that embryos frozen shortly after cell division had begun are no more likely to lead to premature or underweight birth than fresh embryos.

The first study was conducted by a research group at the University of Western Australia. Its findings match those for singletons with the paper referencing numerous studies that document earlier birth, lower birthweight and a higher risk of physical malformation in ART pregnancies when compared with spontaneously conceived pregnancies.

The finding suggests that the increased problems surrounding ART twin birth are not solely a result of difficulties inherent to multiple births but are also associated with assisted reproduction. The finding provides further support to the argument that only single embryos should be implanted in IVF or ICSI procedures. It does not, however, demonstrate whether it is the technique itself or the reproductive abnormalities of the recipients that are the cause.

A spokesperson for the UK's Human Fertilisation and Embryology Authority (HFEA), commenting on the new research, told the BBC that 'clinicians have a duty of care to ensure that patients fully understand what IVF treatment involves and what the risks are, for both themselves and their babies', adding: 'This study is another piece of the jigsaw that women and their doctors need to consider before treatment'.

The second study involved a meta-analysis of 21 studies comparing ART with embryos that had been cryopreserved and those that had not. The conclusion drawn from the pooled data was that there is no significant detrimental effect of the freezing of embryos on health outcomes.

Dr Allan Pacey, secretary of the British Fertility Society, commenting on the two studies, said that 'it is reassuring news about the embryo freezing'. However, he added that 'the issue of IVF twins is concerning, which is why we are trying to move towards single embryo transfer in as many women as possible to give these children the best start in life'.