Dec. 21, 2010 -- Women undergoing in vitro fertilization (IVF) are nearly five times more likely to carry a baby to term if they undergo a single embryo transfer instead of a double embryo transfer, according to an international study.
Researchers led by D.J. McLemon, an investigator at the University of Aberdeen in Scotland, and colleagues conducted a review of medical literature that included 1,367 women from eight different clinical trials. Half of the women underwent single embryo transfer and the other half underwent double embryo transfer.
Weighing Risks and Benefits
There is little information about the pros and cons of single vs. double embryo transfer and whether one increases the risk of miscarriage or premature birth more so than the other. Although a single embryo transfer reduced the complications associated with a multiple pregnancy, including perinatal and maternal illness and even death, there were questions about whether transferring more embryos increased the odds of having a baby. The health care costs of delivering and caring for children born as a result of multiple pregnancies can also be very expensive.
According to the review, 27% of women who underwent a fresh IVF cycle using a single embryo gave birth, compared with 42% of women who underwent double embryo transfer.
Yet when researchers accounted for an additional frozen single embryo that was transferred at a later date following a first single embryo, 38% of women gave birth.
Among women who gave birth, 87% of women who underwent fresh single embryo transfer delivered a single baby at term, compared to 60% of women who underwent fresh double embryo transfer.
Helping Doctors Help Their Patients
The authors say the findings suggest that doctors should recommend single embryo transfer to women undergoing IVF.
“Our review should be useful in informing decision making regarding the number of embryos to transfer in IVF,” they said in a prepared statement. “Given the opportunity for replacing a single frozen thawed embryo in a subsequent cycle, elective single embryo transfer should thus be the default position.”
In an accompanying editorial, Allan Templeton, professor of obstetrics and gynecology at the University of Aberdeen, notes that fertility assistance is a commercially competitive business that may have overshadowed more cost-efficient approaches that still result in success. “Clinicians have been distracted by success rates and do not see the more important healthy outcomes,” Templeton writes. “At a time when the beginning of assisted reproduction is being recognized as an outstanding contribution to medical science, practitioners have a responsibility to develop its use wisely. Doctors managing infertile couples are no longer entitled to take risks with the health of the next generation.”
The findings of the study are published online in BMJ.