Does obesity affect embryo development and quality? A retrospective analysis

Does high body mass index (BMI) impact embryo development and quality?

This study compared morphokinetic parameters and developmental quality of embryos from gonadotrophin-releasing hormone (GnRH) antagonist intracytoplasmic sperm injection cycles among four BMI groups (BMI <18.5, 18.5≤ BMI <25, 25≤ BMI <30, BMI ≥30 kg/m²). Key parameters included time to pronucleus appearance (t2PN), time to pronuclear fading (tPNf), cleavage timings (t2-t8), time to morula and blastocyst formation, synchrony of the second cycle (S2), and duration of the second cycle (CC2). Additionally, the rates of top-quality embryos on day 3 and day 5 were assessed.

The analysis included 617 GnRH antagonist cycles and 1784 viable embryos. No significant differences were found in the number of retrieved oocytes, oocyte maturation rate, fertilization rate, number of embryos created, rate of embryos discarded, or pregnancy rate among the different BMI groups. No differences in any of the embryo morphokinetic parameters were found between the BMI groups, and no differences in the number of top-quality embryos were found between the groups at either cleavage or blastocyst stage. Pairwise comparisons between the BMI groups for the morphokinetic parameters showed no significant differences, except for tPNf which differed significantly between the 18.5≤ BMI <25 kg/m² group and the BMI ≥30 kg/m² group (P = 0.02).

Overall, morphokinetic parameters and embryo quality, as evaluated by time-lapse monitoring, appear to be unaffected by maternal weight, even in extreme BMI subgroups. Moreover, there seem to be no significant differences in implantation, clinical pregnancy, live birth and miscarriage rates across the BMI groups.