Birth outcomes for IVF babies depend on technique, infertility diagnosis

Outcomes of singleton pregnancies in women who conceive by in vitro fertilization (IVF) depend on the technique used and the reason for infertility, a new study from researchers at Baylor College of Medicine shows. Uterine environment may be the key influence on birth weight and length of gestation in such pregnancies.

In a retrospective analysis of data collected by the Society for Assisted Reproductive Technologies (SART) from 2004 through 2006, researchers from the SART Writing Group compared average birth weight and gestational age for single births resulting from standard IVF (ie, the patient carries an embryo created with her own egg), IVF with donor eggs, and IVF with a gestational carrier. They also reviewed the data in light of the patient’s primary diagnosis and whether sperm from her partner or donor sperm was used.

Standard IVF was associated with higher birth weight than IVF with donor eggs and lower birth weight than IVF with a gestational carrier. The finding persisted when variables such as maternal age, number of fetal heartbeats in the first trimester, and male factor infertility were considered. No difference in outcome was seen with partner or donor sperm.

Although male factor infertility didn’t influence birth weight or gestational age, every female-related infertility diagnosis was linked to lower birth weight, and every female diagnosis except “unexplained” infertility was associated with decreased gestational age. The lowest birth weights and gestational ages were associated with “uterine factor” infertility.

The researchers also investigated uterine environment in relation to IVF techniques. Babies born as a result of donor egg transfer had lower birth weights than infants born through standard IVF or a gestational carrier, suggesting that the uterine environment was more important to outcome than egg quality.

The study was published online December 3 in Fertility and Sterility.