Vitamin C

Pregnancy

MotherToBaby's 1 November 2024 sheet says vitamin C supplements and miscarriage have not been well studied and that intake at the recommended amount is unlikely to increase miscarriage chance. The Cochrane 2016 review found no difference in early or late miscarriage in trials comparing vitamin C plus vitamin E with placebo or no vitamin C (RR 0.90, 95% CI 0.65 to 1.26; 4 trials; 13,346 women). A 2026 single-center retrospective case-control study included 65 women with early pregnancy loss and 65 controls. The full-text Table 6 reported an inverse association between dietary vitamin C and loss in the fully adjusted model: highest versus lowest quartile OR 0.17 (95% CI 0.04 to 0.77, p = 0.021), and continuous intake OR 0.99 (95% CI 0.99 to 1.00, p = 0.022). This small, retrospective dietary study cannot establish that vitamin C prevents loss or address supplement doses. The Cochrane review tested supplemental vitamin C plus E, not dietary vitamin C, and found no reduction in miscarriage. MotherToBaby states that vitamin C has not been well studied in relation to birth defects. Carmichael et al. studied 815 craniosynostosis cases and 6,789 controls. Dietary vitamin C associations differed by suture type, and the study does not establish that supplements prevent or cause birth defects generally. MotherToBaby also cites a 1965 report of two infants with classical scurvy whose mothers had an estimated intake of about 400 mg/day during pregnancy. The original article described the cases and proposed a possible conditioning effect, but did not establish causation or document rapid vitamin C metabolism in those infants. The 2025 cohort by Li et al. followed 442 mother-infant pairs and found a nonlinear association between late-pregnancy serum vitamin C and six-month social scores. It measured blood status, not supplement use, and the observational association does not establish a developmental benefit. A 2026 Norwegian cohort of 85,244 children found no adjusted association between maternal vitamin C intake and child type 1 diabetes. These newer findings do not establish that supplementation changes child outcomes. Cochrane's 2015 review included 29 trials and 24,300 women. It found no clear difference in most major outcomes, including preterm birth and clinical preeclampsia, but reported an increased risk of term prelabor rupture of membranes in two vitamin C plus E trials (RR 1.73, 95% CI 1.34 to 2.23; 3,060 women) and a self-reported abdominal pain signal in one trial. The review also reported some subgroup findings for other outcomes, with most trials combining vitamin C and vitamin E, so results cannot be assigned to vitamin C alone. Rumbold et al.'s randomized trial enrolled 1,877 nulliparous women at 14 to 22 weeks and tested 1,000 mg vitamin C plus 400 IU vitamin E daily until delivery. It found no significant difference in preeclampsia, serious infant outcomes, or birth weight below the 10th percentile. Pereira et al.'s 2025 review included 17 trials and 21,567 participants; it found no significant preterm-birth reduction (RR 1.04, 95% CI 0.96 to 1.14) or significant differences in neonatal death, NICU admission, preterm PROM, or birth weight. The Li et al. cohort measured six-month social-development scores, not supplement use or long-term learning. NIH ODS lists pregnancy RDA amounts of 80 mg/day for ages 14 to 18 and 85 mg/day for adults. Its UL table lists 1,800 mg/day for ages 14 to 18 and 2,000 mg/day for adults. MotherToBaby lists 2,000 mg/day for both age groups, so the teen upper-limit values differ. ODS describes diarrhea, nausea, and abdominal cramps among the effects of high intakes. ACOG’s patient FAQ, last updated March 2026 and reviewed December 2025, lists pregnancy RDA amounts of 80 mg/day for ages 14 to 18 and 85 mg/day for ages 19 to 50.

Breastfeeding

LactMed's June 2024 revision describes vitamin C as a normal milk component and states that prenatal-vitamin doses at or near the recommended intake do not alter milk levels. LactMed summarizes milk concentrations of 50 to 90 mg/L in mothers with adequate dietary intake and says routine multivitamin use does not markedly raise levels. Primary studies show response varies. Byerley and Kirksey studied 25 lactating women and found that maternal intake exceeding 1,000 mg/day or ten times the then-current RDA did not significantly change milk vitamin C or calculated infant intake over the short study period. Daneel-Otterbech et al. found that 1,000 mg/day for ten days increased milk vitamin C from 19 to 60 mg/kg in 18 African women with low baseline levels, and from 60 to 70 mg/kg in 10 European women. Zarban et al. randomized 60 breastfeeding mother-infant pairs to 500 mg vitamin C plus 100 IU vitamin E daily for 30 days or no supplement; the intervention increased antioxidant markers in milk and infant urine, but clinical infant outcomes were not reported. This is a biochemical outcome, not evidence of improved infant health. The 2026 Malaysian cohort included 64 first-time mothers and measured milk vitamin C at week 2 and weeks 8 to 12; levels were lower at week 2, and fruit intake correlated with week-2 milk levels. It measured milk composition and diet, not infant health outcomes. LactMed says high maternal intake up to 1,000 mg can increase milk levels, while these studies show that response varies by baseline status, population, intake and duration. MotherToBaby identifies vitamin C as a normal part of breast milk. NIH ODS lists lactation RDA amounts of 115 mg/day for ages 14 to 18 and 120 mg/day for adults, and ULs of 1,800 and 2,000 mg/day. MotherToBaby lists 2,000 mg/day for teens and adults. ODS notes that high intakes can cause diarrhea, nausea and abdominal cramps.

What was tested

Pregnancy research includes systematic reviews of randomized trials, often using high-dose vitamin C and sometimes vitamin E, plus observational studies measuring dietary intake or blood levels. The large trials mostly studied pregnancy outcomes such as preeclampsia, preterm birth and newborn complications, not ordinary RDA-level supplementation or every rare birth outcome. Breastfeeding research includes small milk-concentration studies and one trial that measured antioxidant markers in infant urine; clinical infant outcomes were not reported in that trial.