Serum Vitamin D status is associated with increased blastocyst development rate in women undergoing in vitro fertilisation

Abstract Research Question To determine the relationship between vitamin D (VitD) status and embryological, clinical pregnancy (CP) and live birth (LB) outcomes in women undergoing IVF. Design Cross sectional, observation study conducted at a university-affiliated private IVF clinic. A total of 287 women underwent 287 IVF cycles and received a fresh embryo transfer. Patients had their serum 25-hydroxyvitamin D2/D3 (VitD) determined on the day of oocyte pick up, which was correlated with blastocyst development rate, CP and LB outcomes. Results In stepwise, multi-variable logistic regression models, increases in blastocyst development rate, number, cryopreservation and quality was associated with women with a sufficient VitD status (≥ 20 ng/mL). For a single increase in the number of blastocysts generated per cycle or blastocysts cryopreserved per cycle, the likelihood for the patient to be VitD sufficient was increased by 32% (OR=1.32, CI=1.10-1.58, p=0.002 and OR=1.33, CI=1.10-1.60, p=0.004, respectively). Although CP and LB rates were higher in the sufficient VitD group (by 9.9% and 7.1%, respectively), VitD sufficiency was not significantly associated with these outcomes. Conclusion A strong relationship was observed between blastocyst development and VitD sufficiency. However, there was no association between VitD and CP or LB outcomes. Although not shown in this study, the observed effect on blastocyst development may have downstream implications on subsequent CP or LB rates in larger studies, and may also point to a potential mechanism where sufficient VitD levels are linked to improved IVF outcomes.