Background: Progesterone is an important biomarker of early pregnancy failure. However, literature is limited regarding factors that influence progesterone levels in early pregnancy. Maternal obesity has been associated with adverse pregnancy outcomes such as miscarriages.
Materials and methods: We investigated the association between maternal body mass index (BMI) and serum progesterone level in first trimester singleton pregnancies for 194 women at a tertiary maternity hospital in Singapore, from January 2012 to February 2014. Maternal characteristics and study outcomes were retrieved from clinical records.
Results: Multivariate analysis demonstrated an inverse relationship between first trimester maternal BMI category and serum progesterone level (p=0.012). Obesity (maternal BMI ≥30 kg/m2), relative to normal weight (BMI 18.5-24.9 kg/m2), conferred an increased risk for serum progesterone <35 nmol/L (adjusted OR: 9.14; 95% CI: 2.12 - 39.5; p=0.003). The overall miscarriage rate in our study population was 13.9%.
Conclusions: This study indicates that maternal obesity is associated with low first trimester serum progesterone. Pre-pregnancy weight optimization may be beneficial in regulation of serum progesterone level and maintenance of healthy pregnancy.