In general, assisted fertilisation (AF) single births lead to worse infant health outcomes than births after spontaneous conception. But this difference in health outcomes is much smaller in women who had conceived both spontaneously and with AF, and thus the risk associated with AF single births could be due to causes of infertility rather than the AF procedure itself. These are the conclusions of authors of an Article published early Online and in an upcoming edition of The Lancet.
Dr Liv Bente Romundstad, St Olav's University Hospital, and Department of Public Health, Norwegian University of Science and Technology, Trondheim, Norway, and colleagues did a population-based cohort study to compare pregnancy outcomes in women who had singleton pregnancies conceived both spontaneously and after assisted fertilisation. They assessed differences in birthweight, gestational age, odds of having a small for gestational age baby, premature births, and perinatal deaths in single births (gestation ≥ 22 weeks or birthweight ≥ 500g) born to 2546 Norwegian women (aged over 20 years) who had conceived at least one child spontaneously and another after AF, and compared these with rates in 1200922 single birth controls and 8229 AF controls.
The researchers found that in the whole study population, AF conceptions were associated with lower mean birthweight (by 25g), shorter gestation (by 2.0 days), a 26% increased risk of being small for gestational age, and a 31% increased risk of perinatal death. In the women who had had one child spontaneously and another with AF, AF conceptions resulted in babies only 9g lighter, and gestations only 0.6 days shorter. Both babies were almost equally likely to be small for gestational age. However, the spontaneously conceived baby was more than three times more likely to suffer perinatal death than its AF sibling.
The authors conclude: "Birthweight, gestational age, and risks for small gestational age babies, and preterm delivery, did not differ among infants of women who had conceived both spontaneously and after assisted fertilisation. 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."
In an accompanying Comment, Dr Anja Pinborg, Copenhagen University Hospital, Denmark, and colleagues, say: "Considering that 1-4% of all newborns in Europe are conceived after assisted reproductive technology (ART), safety concerns are important. Reducing the number of multiple births has made improvements, but we need to gain a better biological understanding of the reasons why infertility and ovarian stimulation may have adverse effects on infant health. Consequently, we have to continuously monitor the short and long-term risks of ART."
Dr Liv Bente Romundstad, St Olav's University Hospital, Trondheim, Norway T) +47 905 50207 E) libero@ntnu.no
Dr Anja Pinborg, Copenhagen University Hospital, Denmark contact by e-mail only E) apinborg@rh.dk
for full paper please contact tony.kirby@lancet.com
Journal
The Lancet