Maternal Serum Zinc Concentration during Pregnancy Is Inversely Associated with Risk of Preterm Birth in a Chinese Population

Background: Evidence exists that maternal zinc status during pregnancy is linked to adverse pregnancy outcomes including abortion, fetal growth restriction, and neural tube defects. However, it remains unclear whether maternal serum zinc concentration (SZC) during pregnancy is associated with risk of preterm birth.

Objective: This study was designed to investigate the association between maternal SZC during pregnancy and risk of preterm birth.

Methods: For this substudy of the China-Anhui Birth Cohort Study, 3081 maternal-singleton pairs with detailed birth records and available serum samples were identified. The maternal SZC was determined with flame atomic absorption spectroscopy. A total of 169 preterm births were identified. In this study, the women were divided into tertiles on the basis of their SZC: low (<76.7 μg/dL), medium (76.7-99.6 μg/dL), and high (≥99.7 μg/dL). The ORs for preterm birth were estimated by using multiple logistic regression models.

Results: The median SZC was 87.3 μg/dL (range: 11.1-211 μg/dL). Incidences of preterm birth were 7.3% and 6.0% among subjects with low and medium SZCs, respectively, which were significantly higher than 3.1% among subjects with a high SZC [ORs (95% CIs) for low and medium SZCs: 2.45 (1.60, 3.74), P < 0.001, and 2.00 (1.29, 3.09), P < 0.01, respectively]. After adjustment for prepregnancy body mass index, maternal age, time of serum collection, gravidity, parity, and monthly income, adjusted ORs were 2.41 (95% CI: 1.57, 3.70; P < 0.001) and 1.97 (95% CI: 1.27, 3.05; P < 0.01) among subjects with low and medium maternal SZCs.

Conclusions: Maternal serum zinc concentration during pregnancy is inversely associated with risk of preterm birth in the Chinese population, and the results are driven by maternal SZC in the first trimester.