During pregnancy under normal conditions the plasmatic concentrations of Vitamin C decrease from 0.80 mg/dL to 0.60, 0.57 and 0.54 during the first, second and third trimester respectively [1]. Therefore, the supplementation of Vitamin C for the antioxidant role is not only recommended but necessary.
During pregnancy, the daily requirement is increased to 85 mg per day. The maximum amount of vitamin C you should consume daily is 2,000 mg. If you consume more than 2,000 mg per day, you may experience an upset stomach and symptoms such as stomach pain, diarrhea, and gas. For this reason, intravenous application of vitamin C during pregnancy is necessary. If you take a multivitamin supplement that contains high levels and at the same time eat foods high in this vitamin, you should consult your health care professional. They may advise you to cut back and start taking another multivitamin. You should get a sufficient amount of vitamin C through a healthy diet. At the end of this article you will find suggestions for foods that contain vitamin C.
The data do not support the routine administration of vitamin C supplementation alone or in combination with other supplements for the prevention of stillbirth or neonatal death, poor fetal growth, preterm birth, or preeclampsia. Additional research is needed to elucidate the possible role of vitamin C in the prevention of placental abruption and rupture of the membranes before labor. There was no convincing evidence that vitamin C supplementation alone or in combination with other supplements causes other important benefits or harms [2].
References
[1] Ghate, J., Choudhari, AR, & Ghugare, B. (2011). Antioxidant role of Vitamin C in normal pregnancy.