Zinc

Pregnancy

MotherToBaby says zinc at recommended amounts is unlikely to increase the chance of miscarriage, birth defects, or other pregnancy problems, and it does not provide trimester-specific estimates. MotherToBaby lists a recommended amount of 11 mg/day for pregnant adults and 12 mg/day for ages 14 to 18; the upper limits are 40 and 34 mg/day. ODS says low serum zinc might be linked with low birth weight and preeclampsia, but these deficiency findings do not show that usual supplements cause those outcomes. WHO says zinc supplements in pregnancy are only recommended in rigorous research. Cochrane's 2021 review included 25 randomized trials with over 18,000 women and babies. It found little or no difference for preterm birth, stillbirth, perinatal death, birth weight, low birth weight, and small-for-gestational-age birth; evidence about neonatal death was very uncertain. Diao et al.'s 2025 review included 77 trials and reported possible benefits from zinc alone for several growth or newborn measures, but no extra benefit from zinc plus iron and folate compared with iron and folate alone. Only 10 trials were judged at low risk of bias overall, 7 were high risk, and 87% had concerns or high risk in the randomization domain. The review could not reliably analyze dose, duration, or frequency because those details were not reported well. Recent studies do not settle the question. In a 2026 Ghana randomized trial, 125 women per group received either daily multiple micronutrients containing 30 mg zinc or iron and folic acid; late-pregnancy plasma zinc did not differ significantly, and few birth outcomes were associated with maternal zinc measures. A 2026 Chinese cohort measured maternal zinc once in late pregnancy in 291 pairs and found associations with some infant growth measures at 6 months but not 12 months; it was not a supplement trial, follow-up declined, and infant measurements were parent-reported. A 2025 study of 41 adolescent mothers assessed dietary zinc, not supplements; its authors said the observational design could not establish cause and effect. These studies concern different exposures and outcomes and do not establish that routine zinc supplements improve pregnancy outcomes for everyone.

Breastfeeding

MotherToBaby says zinc is a normal part of breast milk and lists daily recommended amounts of 12 mg for adults and 13 mg for ages 14 to 18 while breastfeeding. LactMed says oral zinc doses of 15 mg/day or less from prenatal vitamins or other multi-mineral supplements do not alter milk zinc; doses of 15 to 25 mg/day have negligible effects. Krebs et al. randomized 71 lactating women to 15 mg/day zinc or placebo and found that supplementation did not change milk zinc. Moser-Veillon and Reynolds randomized 40 women to supplements that included 0 or 25 mg/day zinc and also found no effect on milk zinc. These trials measured milk concentrations, not infant clinical outcomes. LactMed says lozenges and nasal sprays have not been studied in lactation. The prescription-treatment evidence is different. The GALZIN label on DailyMed and EMA WILZIN information warn against breastfeeding during zinc acetate treatment for Wilson disease because infant copper deficiency may occur. LactMed says zinc acetate up to 100 mg/day may raise milk zinc without taking it above the usual range. Kodama et al. studied 18 Japanese mothers with Wilson disease and 25 controls; 6 mothers used zinc alone and 1 used zinc with trientine. Milk zinc was higher in zinc-treated mothers but remained within the control range. The infants were reported to have normal development, but the study did not measure infant copper and was a small observational case series. These data do not resolve the label warning or establish the effects of other doses and products.

What was tested

Pregnancy research includes randomized trials and reviews of zinc alone or combined with other nutrients, often compared with placebo or iron and folic acid. These trials studied supplement effects on zinc levels and pregnancy or newborn outcomes; they do not represent every diet, dose, or patient group. Breastfeeding trials by Krebs et al. and Moser-Veillon and Reynolds measured milk zinc after 15 mg/day and 25 mg/day supplements, respectively, but not infant health outcomes. Kodama et al. studied milk composition and reported infant development during prescription treatment for Wilson disease. The GALZIN and WILZIN product information concerns prescription zinc acetate for Wilson disease, not routine nutritional supplements.