London, Jan 12: Transferring two embryos rather than only one can boost the chances of a successful birth in women over 40 taking IVF treatment, researchers say.
This is the finding of one of the largest studies of success rates at fertility clinics.
Transferring two embryos raises the risk of a twin birth – the greatest hazard in fertility treatment – but researchers say that, for older women, the risk could be worth taking.
In the past, clinics transferred multiple embryos in the belief that this would boost the chances of a successful pregnancy and birth. But twin and triplet pregnancies carry a higher risk of premature birth, low birth weight and other hazards.
As a result, in 2008 the Human Fertilisation and Embryology Authority (HFEA) ordered IVF clinics to reduce their multiple birth rate, then 24 per cent, to 15 per cent by restricting patients to a single embryo, except where there were medical reasons, such as a recent failed treatment cycle, for transferring two.
The policy has worked and the multiple birth rate is down to 18 per cent for IVF clinics nationally while live birth rates have steadily risen.
But the study, by Professor Debbie Lawlor and colleagues at the Medical Research Council in Bristol, found that women over 40, who have the lowest chance of having a baby, have a low risk of a multiple birth as they are less likely to carry a twin pregnancy to term.
“Our findings provide some support for the transfer of two embryos in women older than 40 years, because the risks of pre-term and low birthweight were lower than those in younger women,” the Independent quoted Lawlor as saying.
The researchers added that transferring three embryos should never be attempted, mainly because it increased the risk of severely premature birth.
The study analysed more than 33,000 live births from 124,000 cycles of treatment conducted in UK clinics.
The researchers concluded in The Lancet that “greater freedom” should be given to clinicians and patients “to decide whether to transfer one or two embryos.” (ANI)