Rostami M, Simbar M, Amiri M, et al. - Analyzing data collected from the Khuzestan Vitamin D Deficiency Screening Program in Pregnancy, researchers investigated the thresholds for the circulating levels of 25-hydroxyvitamin D (25(OH)D), linked with adverse pregnancy outcomes, including preterm labor, preeclampsia (PE), and gestational diabetes mellitus (GDM), using a generalized additive model. They used data of 1,763 pregnant women, referred to the health centers of Masjed-Soleyman and Shushtar (Khuzestan Province, Iran), whose serum vitamin D status during the third trimester of pregnancy was available. Findings from the adjusted generalized linear model indicated a significant rising trend in the risk of pregnancy outcomes by decreasing 25(OH)D levels. Based on overall findings, researchers recommend attaining a 25(OH)D cut-off level of > 15 ng/mL in the preconception period, for the prevention of adverse pregnancy outcomes.