Abstract: Objective To examine the association between zinc status and erythrocyte parameters in early pregnancy, and to evaluate the effect of zinc supplementation during early gestation on subsequent changes in erythrocyte parameters. Methods A retrospective cohort study was conducted, enrolling 100 women in early pregnancy who attended their first antenatal nutrition consultation at Peking Union Medical College Hospital in 2024. Participants were classified into a zinc supplementation group(n=25) and a control group(n=75) based on the presence of zinc deficiency(serum zinc ＜700 μg/L) and receipt of zinc supplementation(zinc sulfate 150 mg/day). All participants underwent follow-up in mid-pregnancy, during which serum trace elements and erythrocyte parameters were reassessed. Routine antenatal care and nutritional counseling were provided to all. Using early pregnancy as the baseline, changes(Δ) in trace elements and erythrocyte parameters by mid-pregnancy were calculated. Welch′s t-test was used to assess between-group differences, while linear mixed-effects models were employed to evaluate the longitudinal impact of zinc supplementation on erythrocyte parameters, controlling for individual variability and adjusting for age, parity, pre-pregnancy body mass index, and trace element levels. Results In early pregnancy, serum zinc, serum ferritin, hemoglobin(Hb), red blood cell count(RBC), and hematocrit(Hct) were significantly lower in the zinc supplementation group than in the control group(all P＜0.05), and their subsequent declines were significantly attenuated by mid-pregnancy. Linear mixed-effects modelling showed that zinc supplementation was an independent protective factor for Hb, RBC, and Hct, ssociated with higher levels of these parameters by 4.98 g/L, 0.17×10¹²/L, and 1.43%, respectively, in mid-pregnancy compared to the control group(all P＜0.001). Conclusions Zinc supplementation in early pregnancy significantly reduces the mid-pregnancy decline in ferritin and erythrocyte parameters. These findings provide new insights into the prevention and management of anemia during pregnancy and offer evidence-based support for zinc nutritional interventions in gestation.

Key words: zinc, zinc supplementation, erythrocyte parameters, hemoglobin, anemia in pregnancy