Serum calcium level at 32 weeks of gestation could be applied as a predictor of preterm delivery: a retrospective study

Preterm delivery (PTD) is associated with severe adverse maternal and neonatal outcomes and higher medical costs. Therefore, PTD warrants more attention. However, predicting PTD remains a challenge for researchers. This study aimed to investigate potential prenatal predictors of PTD. We retrospectively recruited pregnant women who experienced either PTD or term delivery (TD) and underwent laboratory examinations at 32 weeks of gestation. We compared the test results between the two groups and performed logistic regression analysis and receiver operating characteristic (ROC) curve analysis to identify risk factors and predictive factors for PTD. Our investigation revealed that the PTD cohort exhibited statistically significant elevations in lymphocyte count, mean corpuscular hemoglobin concentration, calcium, uric acid, alkaline phosphatase, triglycerides, and total bile acids. Conversely, the PTD group demonstrated statistically significant reductions in mean corpuscular volume, homocysteine, neutrophil to lymphocyte ratio (NLR), monocyte to lymphocyte ratio (MLR), neutrophils to (white blood cells-neutrophils) ratio (dNLR), and (neutrophils x monocytes) to lymphocyte ratio (SIRI). The ROC curve analysis revealed that calcium had an area under the curve (AUC) of 0.705, with a cut-off value of 2.215. Logistic regression analysis showed that premature rupture of membranes was an independent risk factor for PTD. Our study demonstrated that serum calcium levels, NLR, dNLR, and other laboratory tests conducted at 32 weeks of gestation can serve as predictors for PTD. Furthermore, we identified premature rupture of membranes as a risk factor for PTD.