The increased risk of complications during pregnancy and at birth observed in babies conceived through assisted reproductive technology (ART) may be the result of parent's underlying infertility problems rather than the technology itself, a new study has revealed. In a report published in The Lancet, researchers found that children conceived through ART were born earlier, had a lower average birth weight and were more at risk of being still born than naturally-conceived children in the general population. However, their birth statistics were no different from those of their naturally-conceived siblings. This suggests that the problems associated with ART may in fact arise from the same inherent factors that cause the couple's infertility.
Between one and four per cent of babies born in Europe are conceived through ART, and it is well known that these children are more likely to have problems before, during and after birth. There has been concern that this is attributable to the technologies used - the techniques for storing sperm and eggs, fertilisation and implantation. The new study, led by Dr Liv Bente Romundstad from St Olav's University Hospital in Trondheim, Norway, sought to investigate this further by examining detailed records kept at the Medical Birth Registry of Norway. The researchers looked at more than 1.2 million births from January 1984 to June 2006 and compared 1,200,922 births following natural conception with 8,229 births after ART. They examined only single pregnancies, as twins and triplets are already known to have a greater risk of pre- and post-natal problems.
When the researchers compared the two groups as a whole, their analysis was in line with previous findings. Babies conceived through ART were on average 25 grams lighter, born two days earlier, and were at greater risk of having a low weight for their gestational age or dying in the period around birth. However, the researchers then narrowed their investigation to include only children born to 2, 546 women who had conceived at least one child naturally and at least one child through ART. They found that amongst these children, there was no difference in the likelihood of complications after ART compared to natural conception. Interestingly, babies conceived through ART were less likely to be still-born than their naturally-conceived siblings.
Dr Romundstad concluded that 'the adverse outcomes of assisted fertilisation that we noted compared with those in the general population could therefore be attributable to the factors leading to infertility, rather than to factors related to the reproductive technology'. Dr Allan Pacey of the University of Sheffield, UK, and the British Fertility Society commented to BBC News Online: 'It is reassuring to see that, in this study at least, the laboratory procedures [used in ART] were not contributing to adverse birth outcomes for those born'.