While it is typically safe to take vitamin C during pregnancy, it is always best to consult with a doctor or nutritionist about prenatal supplements. Most prenatal vitamins contain vitamin C, and any healthy diet will also contain a substantial amount of this vital antioxidant. The recommended daily allowance (RDA) by the US Food and Drug Administration (FDA) is 85mg per day, which is slightly higher than the RDA for a healthy adult that isn't pregnant. The maximum suggested intake for most people is 2,000mg per day, so it may be a good idea to remain below this level, regardless of pregnancy.
While it may be healthy in moderation, excessive consumption of vitamin C during pregnancy may cause various complications. Certain studies have indicated that excessive amounts, beyond the recommended maximum daily intake, could lead to pre-term birth, or even the presence of scurvy in the infant. This level of vitamin C is likely only possible by taking too many vitamin C supplements. In other words, doctor-recommended prenatal vitamins and consuming various foods that contain vitamin C are unlikely to contain such high levels of the nutrient.
There are various folk remedies that promote megadoses of vitamin C to induce miscarriage, though it is unclear as to whether scientific evidence exists to support such ideas. Various studies exist in which the mother took large amounts of vitamin C during pregnancy without seriously harming the fetus.
Vitamin C is an essential nutrient that the human body is incapable of synthesizing on its own, so it must be obtained either through the diet or supplements. Similarly, it is vital to the proper development of a fetus in utero. Low levels of vitamin C during pregnancy may not actively cause any complications, though such levels have been observed in various cases in which a defect or complication was present. These problems may have been caused by the low vitamin C or various other nutritional deficiencies.
It is probably safest to stick to taking normal levels of vitamin C during pregnancy, or otherwise obtain a physician's advice. High intake levels may not cause problems and low levels may not be the root cause of complications, but simply taking the RDA will, in most cases, provide both mother and baby with enough of the nutrient to keep them healthy.
While 85mg per day is the RDA for vitamin C during pregnancy, after the baby is born, the new mother may want to increase her consumption. The recommended daily intake of vitamin C for a breastfeeding mother may be as high as 120mg each day. If the mother is vitamin C-deficient, evidence suggests she may pass on very near to the full amount of vitamin C taken as supplements to the infant. For this reason, it may be a good idea for nursing mothers to check with their doctors to be sure they aren't vitamin-deficient.