Relationship between serum levels of vitamin D and the success rate of pregnancy in an in vitro fertilization cycle (IVF): A prospective cohort study

Vitamin D deficiency in women may play a role in the pathogenesis of infertility and menstrual dysfunction. Due to the high percentage of insufficient vitamin D serum levels in women of reproductive age, recently the role of vitamin D in reproductive physiology has also been considered. The present study was performed with aim to determine the relationship between vitamin D serum level and pregnancy success rate in a cycle of in vitro fertilization (IVF).

In this prospective cohort study conducted in 2022, 116 reproductive-aged women diagnosed with both primary or secondary infertility in their first IVF cycle were studied. Based on the serum level of vitamin D in the blood sample measured by the Elisa method 7 days before embryo transfer, the participants were divided into two groups: deficiency or insufficient and sufficient and were evaluated at the gestational age of 7 weeks in terms of the presence of intrauterine gestational sac and the presence of heartbeat. Data collection tools included socio-demographic, infertility, and nutrition questionnaires, and checklists for recording test results and pregnancy outcomes. Data were analyzed by SPSS statistical software (version 24) and chi-square, independent t-test, and multivariate logistic regression. P<0.05 was considered statistically significant.

The mean of vitamin D serum level in people with successful pregnancy and unsuccessful pregnancy was 60.3±26.8 and 66.5±37.4, respectively (p=0.361) and the frequency of pregnancy success in vitamin D sufficient and insufficient group was 23.3% and 13.6%, respectively (p=0.247). Based on multivariate logistic regression and adjusting for confounding variables, there was no statistically significant difference between the groups in terms of pregnancy success rate (odds ratio: 2.08; 95% (CI): 0.45 to 9.5; (p=0.346).

Although vitamin D serum level in infertile women with successful pregnancies was more than in women with unsuccessful pregnancies, however, this difference was not significant.