Longitudinal growth of French singleton children born after in vitro fertilization and intracytoplasmic sperm injection. Body mass index up to 5 years of age.

Background: The literature presents conflicting results on the epigenetic effect of in vitro fertilization (IVF) on the short-term and mid-term growth of children. These contradictory results may be related to the use of heterogeneous methodologies and non-longitudinal data. The goal of this study was to compare the body mass index (BMI) of children conceived via IVF and spontaneous conception (SC) children, using longitudinal data from birth to 5 years.

Methods: This study compared 118 singleton children born after in vitro fertilization, with or without intracytoplasmic sperm injection (ICSI), selected from a pre-existing single-center cohort to 320 SC children from the same geographic area. BMI and its evolution were analyzed using the mixed-effect model during three periods: before standing acquisition (from birth to 1 year of age), during standing acquisition, and the following period from 2 to 5 years of age.

Results: BMI means were not significantly different between groups regardless of the period, when adjusting for confounding factors related to parents, pregnancy, and children's characteristics and lifestyle. Nevertheless, during the standing acquisition period, children born after IVF-ICSI presented a less significant decrease in BMI (P<0.05). In addition, for each period we identified influencing factors (maternal BMI, level of wealth indicator) associated with BMI.

Conclusion: In the study population, the suspected epigenetic influence of IVF reported in the literature was not observed for BMI from birth to 5 years of age. Further investigations need to be conducted to determine if the suspected influence of IVF on adiposity could be expressed through other parameters.