Association of preconception and pregnancy dietary zinc and selenium intake with preeclampsia risk: results from a large birth cohort study

Preeclampsia is a major cause of maternal and perinatal mortality. As key antioxidants, the trace elements zinc and selenium have been demonstrated to play important roles in antioxidant defence, immune regulation and vascular function. In addition, previous studies have suggested that these micronutrients may influence placental health. This study aimed to investigate the association between dietary zinc and selenium intake and preeclampsia among pregnant women in urban Lanzhou, China. This case-control analysis was conducted using data from a prospective birth cohort involving 8746 pregnant women from Lanzhou, China, comprising 282 cases of preeclampsia and 8464 controls. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations of total zinc and selenium intake with preeclampsia after adjusting for potential confounding factors; Restricted cubic spline (RCS) analyses were performed to explore potential dose-response relationships; Joint analyses were conducted by categorizing zinc and selenium intakes into quartiles. Furthermore, stratified analyses were conducted to ascertain the robustness of the findings. Multivariable logistic regression analysis revealed that women with lower dietary zinc and selenium intakes before and during pregnancy had significantly higher odds of developing preeclampsia; In subgroup analyses, the inverse associations of zinc and selenium intake with preeclampsia were more pronounced in severe and early-onset cases; RCS curves indicated nonlinear dose-response associations between dietary zinc and selenium intake and preeclampsia odds for preconception zinc (P for nonlinearity < 0.001), pregnancy zinc ( P = 0.0416), and preconception selenium ( P = 0.0277), with excessively low intake being associated with higher odds. For selenium intake during pregnancy, the nonlinear term was not statistically significant ( P = 0.0824). Joint analyses showed that women with low dietary zinc and selenium intake had higher odds of preeclampsia compared with those with high intake of both nutrients. However, no statistically significant multiplicative interaction was observed. Therefore, the potential implications of combined zinc and selenium intake patterns before and during pregnancy warrant further investigation. Low dietary intake of zinc and selenium was associated with higher odds of preeclampsia. Higher dietary intake of zinc and selenium was associated with lower odds of preeclampsia within the observed intake range. RCS analyses suggested nonlinear associations within the observed intake ranges. These findings provide epidemiological evidence for further investigation of nutritional approaches related to preeclampsia prevention.