More than 200 excess infant deaths a year in England and Wales are associated with multiple births after assisted conceptionBMJ 2006; 332 doi: https://doi.org/10.1136/bmj.332.7553.1294-d (Published 01 June 2006) Cite this as: BMJ 2006;332:1294
Problems associated with multiple births after assisted conception techniques, including in vitro fertilisation, may account for more than 220 perinatal and infant deaths a year in England and Wales, new research indicates.
The United Kingdom urgently needs to move towards single embryo transfers for in vitro fertilisation, conclude the authors of the study, which aimed to quantify the excess number of deaths associated with multiple births after assisted conception (Br J Obstet Gynaecol 2006;113:738-41).
The chance of a multiple birth after in vitro fertilisation is around 45%, says the report. It adds that multiple birth is largely thought to be responsible for the higher risk of perinatal and infant mortality in babies born as a result of the technique.
Although the UK regulator, the Human Fertilisation and Embryology Authority, has limited the number of embryos that can be transferred during assisted conception techniques, the authors say that the rate of twin births has remained constant, despite a fall in the number of triplet births.
The authors, from the Centre for Research in Primary and Community Care at the University of Hertfordshire, used birth statistics and linked perinatal and infant mortality data to estimate the excess number of stillbirths and infant deaths in England and Wales in 2001 among twins and higher order multiple births after assisted conception.
They then assessed the likely number of stillbirths and infant deaths that could have been avoided if all infants born as a result of assisted conception had been singletons or monozygotic twins.
The results show that some 73 deaths could have been avoided in 2001 if all infants born after in vitro fertilisation had been born as singletons or as naturally occurring monozygotic twins. This is equivalent to 1% of all perinatal and infant deaths. When all possible types of assisted conception were modelled (including ovarian stimulation, which is not regulated in the UK) they estimated the proportion of avoidable perinatal and infant deaths could be as high as 3.5% −-− or more than 220 perinatal and infant deaths a year.
“The much increased risk of multiple birth in babies conceived following infertility treatment continues to constitute a public health burden, which is largely preventable,” the authors wrote. “As current fertility trends suggest that the number of people seeking assisted conception is likely to continue to increase, this issue needs to be addressed with some urgency.”
They go on to say that the number of multiple births associated with in vitro fertilisation can be reduced by restricting the number of embryos transferred to the womb. “Sweden was one of the first countries to systematically move towards single embryo transfer. And their experience indicates that [it] does not necessarily compromise the ‘take home baby’ rate but does dramatically reduce the multiple birth rate.”
“A move towards single embryo transfer, together with better population based monitoring data for outcomes and unregulated forms of assisted conception, are high public health priorities for the UK,” they conclude.