Washington, DC -- The single biggest risk to babies conceived by assisted reproductive technology (ART) is multiple gestation (i.e. twins, triplets, or more) according to a new Committee Opinion issued today from the American College of Obstetricians and Gynecologists (ACOG). ACOG stresses that this risk can be effectively managed by limiting the number of embryos transferred. Additionally, the Committee Opinion suggests ART patients should be counseled about the risks of adverse outcomes associated with multiple pregnancies including poor infant outcome, low birth weight, and prematurity.

Any treatment or procedure involving the handling of human eggs and sperm, or embryos, with the intent of establishing a pregnancy is defined as ART. This includes in vitro fertilization (IVF) but excludes techniques such as artificial insemination and superovulation drug therapy.

Intense motivation for a successful pregnancy and the substantial cost of ART are factors that may cause parents to request the transfer of more embryos than necessary for a successful pregnancy. Informing parents of the obstetric risks and socioeconomic consequences of multiple births may modify their decision regarding the number of embryos to be transferred.

Newborns conceived through ART are at higher risk for prematurity, low birth weight, and a higher perinatal mortality rate. Women who become pregnant through ART are more likely to have preeclampsia, gestational diabetes, preterm delivery, and vacuum or forceps delivery. Though a number of the adverse outcomes associated with ART may actually be linked to the cause of infertility itself rather than the treatment for this condition, risks increase substantially when the mother is carrying more than one fetus. Efforts to prevent multifetal pregnancies are integral to improving maternal and fetal health. Studies have shown that transferring just two embryos can limit the occurrence of triplets in younger, good-prognosis candidates without significantly decreasing the overall pregnancy rate.

Within the last 20 years the use of ART has greatly increased, helping many infertile couples achieve pregnancy. However, with this increase in ART pregnancies came a boom in multiple births. From 1996-1999, 33% of all multiple births in the US were attributed to ovulation induction or ART. Although these numbers declined from 1998-2001, ART has been associated with a 30-fold increase in multifetal pregnancies compared with the rate of spontaneous twin pregnancies.

The American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology have developed updated recommendations on the number of embryos per transfer to reduce the risk of multiple gestation. ACOG supports adherence to these recommendations and the overall effort toward lowering the risk of multiple gestations with ART.

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