Embryo culture media and neonatal birthweight following IVF.

BACKGROUND: Infants conceived from IVF are at increased risk for low birthweight. Animal studies suggest that embryo culture medium influences birthweight but it is unknown whether this association exists in humans. This study examines the relationship between culture medium and birthweight following IVF.
METHODS: We identified all IVF cycles with start dates between 1 January 1999 and 31 December 2008 that used autologous oocytes with resulting embryos cultured in G1.3, Global or G1.5 medium. The population was restricted to singleton deliveries following Day 3, fresh single embryo transfer, or twin deliveries following Day 3, fresh double embryo transfer, at a gestational age of ≥ 34 weeks. Only the first cycle during the study period was included for each woman. Women were excluded if the number of gestational sacs on ultrasound differed from the number of infants born. Variables were evaluated with the χ²-test or analysis of variance. Multiple linear regressions controlled for potential confounders.
RESULTS: Of the 198 women with singleton deliveries, 102 embryos were cultured in G1.3, 53 in Global and 43 in G1.5 medium. Of the 303 twin deliveries, 172 pairs of embryos were cultured in G1.3, 58 in Global and 73 in G1.5 medium. No significant association between culture medium and birthweight was observed, even when controlling for potential confounders.
CONCLUSIONS: This retrospective study demonstrated no significant association between embryo culture medium and birthweight following IVF. Although our careful selection of patients minimized the influence of potential confounders, further research is required to elucidate this issue with larger numbers of patients.