June 21, 2005 -- New findings should help calm fears that conception through assisted reproduction poses an inherent danger to the baby.
A new European study shows that babies born as a result of infertility treatments are as healthy as those conceived without help from medical science -- as long as only one embryo is transferred.
The research also helps validate the move toward transferring fewer embryos in certain women undergoing assisted reproduction.
In an effort to reduce multiple births, several European countries, including Belgium, now mandate that only a single embryo be transferred into the uterus when there is a higher likelihood of pregnancy. But a fertility expert tells WebMD that this isn't a good option for many American women.
"The single-embryo transfer strategy does seem to be working, and I see no reason that it should not be expanded to include more women with a good prognosis for having a baby," gynecologist and researcher Diane De Neubourg, MD, tells WebMD. She presented her study in Copenhagen, Denmark, at a meeting of the European Society of Human Reproduction and Embryology.
Singles Babies Are Healthier
Most problems from assisted reproduction stem from twin, triplet, and higher-order pregnancies. But the risk of major birth defects and low birth weight also seems to be higher for single babies conceived though assisted reproduction.
It has not been clear whether this increase in risk is caused by infertility procedures like in vitro fertility (IVF) and intracytoplasmic sperm injection (ICSI), or whether it is related to the infertility itself.
In an effort to address this issue, De Neubourg and colleagues from Antwerp's Centre for Reproductive Medicine followed women undergoing assisted reproduction in Belgium between 1998 and 2003. They then compared results of babies born to women who had single-embryo transfers to babies born without the use of assisted reproduction.
A third of the women undergoing assisted reproduction had single-embryo transfers. But the percentage increased over time, presumably due to changes in the transfer policy, from 12% in 1998 to 54% in 2003.
The Belgium mandate calls for all women with a higher likelihood of pregnancy younger than 36 to have a single embryo transfer during her first assisted reproduction attempt.
The proportion of single, rather than multiple-birth, pregnancies also increased, from 66% of all assisted conception pregnancies in 1998 to 87% in 2003.
De Neubourg tells WebMD that when compared with babies born to mothers who conceived spontaneously, the single-embryo-transfer babies had similar birth weights. They were also no more likely to be born preterm and the frequency of stillbirths was the same in both groups.
U.S. Patients Older
Women in Europe undergoing assisted reproduction are more likely to be considered good candidates for single transfer than those in the U.S., says American Society for Reproductive Medicine (ASRM) Executive Director Robert Rebar, MD.
That's because assisted reproduction is routinely paid for by government health plans in Europe, whereas infertile American couples usually end up paying for infertility treatments out of pocket. As a result, women in the U.S. tend to be older and thus have a harder time getting pregnant.
Rebar spoke to WebMD Tuesday from the European meeting.
"The average age of a woman undergoing IVF in Europe is 32, while the average age in the U.S. is 37," Rebar says. "That is a significant difference. While the goal is certainly single-embryo transfer, only a small minority of patients in the U.S. would qualify for it."
Last fall, the ASRM, in conjunction with the Society for Assisted Reproduction Technology, issued new guidelines on embryo transfers. The groups now call for no more than two embryos to be transferred in women under the age of 35 who have a reasonably good chance of having a successful pregnancy.
And it calls on doctors to consider transferring a single embryo in patients with the highest likelihood of pregnancy. That means those undergoing their first cycle of assisted reproduction who have more than one good-quality embryo suitable for freezing.
Though it is too soon to know for sure if infertility clinics have changed their practices as a result of the new guidelines, Rebar says he believes they have. He says it is impossible to say how many American women seeking treatment for infertility are good candidates for single embryo transfer.