Women with luteal phase defect, who are at an increased risk of recurrent miscarriages, may be helped by supplementing with vitamin C, according to researchers. Luteal phase defect is marked by insufficient progesterone levels during the luteal phase, the time between ovulation and the onset of menses. The hormonal imbalance results in menstrual disorders, infertility and recurrent miscarriages.

While a number of factors may be involved in luteal phase defect, recent research has suggested that oxidative (free radical) damage may play a role. Women with the disorder have been found to have significantly lower levels of antioxidants, such as vitamin C, vitamin E and glutathione, than in healthy women.

To test the benefits of antioxidant supplementation, 150 women with luteal phase defect had levels of estrogen and progesterone monitored for three menstrual cycles. The participants were randomly assigned to receive 750 mg of vitamin C daily or no treatment, beginning at the onset of the third cycle of the study.

The researchers found that, in those women taking vitamin C, progesterone levels increased significantly whereas there was no change in women receiving no treatment. Estrogen levels also increased in the vitamin C group but not the untreated group. There was also a significantly higher pregnancy rate in the vitamin C group than in the untreated group. In fact, 25% of the women receiving vitamin C became pregnant within six months of starting treatment, compared to only 11% of untreated women.

The researchers say their results suggest that vitamin C improves hormone levels and increases fertility in some women with luteal phase defect, but that placebo-controlled trials are needed to confirm the benefits and to identify the optimum amount of vitamin C.

Fertil Steril. 2003 Aug;80(2):459-61