The analysis used data collected through a prospective birth cohort but compared women who developed preeclampsia with controls drawn from the same cohort in a case-control design. Preeclampsia is a major cause of maternal and perinatal mortality. Zinc and selenium were investigated because they are key antioxidants involved in antioxidant defence, immune regulation and vascular function, and previous studies have suggested that these micronutrients may influence placental health.

The researchers examined total dietary intake during two stages: before conception and during pregnancy. Unconditional logistic regression was used to estimate odds ratios and 95% confidence intervals after adjustment for potential confounding factors. The multivariable results showed significantly higher odds of preeclampsia among women with lower zinc and selenium intake both before and during pregnancy.

The inverse associations were more pronounced in subgroup analyses involving severe and early-onset cases. Evidence of nonlinearity was strongest for preconception zinc, for which the P value for nonlinearity was below 0.001. The corresponding values were 0.0416 for pregnancy zinc and 0.0277 for preconception selenium.

For selenium intake during pregnancy, however, the nonlinear term did not reach statistical significance, with P = 0.0824. Taken together, the spline findings support nonlinear associations within the observed intake ranges, particularly for the three exposures that produced statistically significant nonlinearity tests. Joint analyses added information about whether low intake of the two nutrients together was associated with different odds from patterns involving other intake combinations.

Women with low dietary intake of both zinc and selenium had higher odds of preeclampsia than women with high intake of both nutrients. The study did not detect a statistically significant multiplicative interaction between zinc and selenium, so the combined results do not demonstrate that one nutrient modifies the association of the other or that a specific joint mechanism accounts for the observed pattern. The stronger findings among severe and early-onset cases likewise describe differences in the stratified associations without establishing why those differences occurred.

Because this was an observational cohort-based case-control analysis, the results identify associations rather than causal effects, and their scope is limited to the participants and intake range examined in urban Lanzhou. The investigators said the implications of combined zinc and selenium intake patterns warrant further investigation, leaving the central conclusion unchanged: within this cohort, low dietary intake of both trace elements was linked to higher odds of preeclampsia, with no statistically significant interaction detected between the nutrients.

Subject of Research: Associations between dietary zinc and selenium intake around conception and during pregnancy and preeclampsia odds in a Lanzhou birth cohort

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

Article References: Tian, Q., Fu, H., Yang, C., Cao, L., Wang, Z., Mao, B., & Yang, L. (2026). Association of preconception and pregnancy dietary zinc and selenium intake with preeclampsia risk: results from a large birth cohort study. BMC Public Health. https://doi.org/10.1186/s12889-026-29914-5

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29914-5

Keywords: preeclampsia, zinc, selenium, dietary intake, pregnancy, preconception, birth cohort, maternal health, micronutrients, Lanzhou, Association, dietary