To investigate the causal relationship between 11 trace elements(calcium,iron,zinc,selenium,magnesium,copper,vitamin A,vitamin C,vitamin D,vitamin E,carotene),22 common dietary factors(alcohol consumption,beef,bread,cereal,cheese,coffee,cooked vegetable,dried fruit,fresh fruit,lamb,non-oily fish,oily fish,pork,poultry,processed meat,raw vegetable,salt added to food,tea,hot drinks,carbonated beverage,garlic intake,Chinese chive) and hyperemesis gravidarum using Mendelian randomization.

All data were summarized by using Genome-Wide Association Studies(GWAS),with single nucleotide polymorphisms(SNPs) as instrumental variables.Analyses were performed using inverse variance weighting,weighted mode,MR Egger,and weighted median.Cochrane's Q test was used to identify heterogeneity of results.MR Egger intercept test and "leave-one-out" test were applied to evaluate the robustness of the associations between the 11 trace elements,22 dietary factors and hyperemesis gravidarum.

The results showed that vitamin D supplementation could reduce the risk of hyperemesis gravidarum[OR=0.48,95%CI(0.30,0.75)].No significant effects of the other 10 trace elements or 22 dietary factors on the risk of hyperemesis gravidarum were observed(P>0.05).There was no horizontal pleiotropy or heterogeneity(P>0.05),indicating the robustness of the results.

Vitamin D could reduce the risk of hyperemesis gravidarum.No effects of the other 10 trace elements or 22 dietary factors on increasing or decreasing the risk of hyperemesis gravidarum were found temporarily.