Does the length of time during which embryos are cultured in vitro affect the birthweight of the infants?
The duration of the embryo culture period is a significant factor in determining the birthweight of the infants.
IVF children show adverse perinatal outcome when compared with the general population and increased incidence of preterm birth and low birthweight is commonly observed.
A retrospective cross-sectional cohort study including 1079 infants born after treatment at the Family Federation of Finland Fertility Clinic in Helsinki, between 2000 and 2010.
All singleton IVF children were included. The gestation- and gender-adjusted birthweights of the babies were analyzed according to mother's age, BMI, and parity, type of treatment (IVF or ICSI), main cause of infertility and embryo culture period. Two outcomes were investigated: the birthweight and the proportion of small and large for gestational age (SGA and LGA) infants. Multiple linear regression analysis was performed to show the significance of each individual factor on determining the birthweight of the babies born.
In the study group as a whole, the distribution of the SGA and LGA babies showed no deviation from the growth charts of the general population. However, when the birthweight of the children was analyzed according to the length of embryo culture from Day 2 to Days 5-6, an increase in the proportion of LGA babies was found (D2 9.4%, D3 11.5%, D5-6 18.8%; D2 n = 871, D3 n = 139, D5-6 n = 69). Multiple linear regression analysis showed that BMI (P