The effect of oral contraceptive therapy and of pregnancy on serum folate levels of rural Sri Lankan women.

Serum folate level, packed cell volume and haemoglobin concentration of apparently healthy rural Sri Lankan women, between 20 and 45 years and earning up to Rs. 500 (Sri Lankan Rs. 35 congruent to 1 pound Sterling) per month, were estimated during pregnancy and when on oral contraceptive (OC) treatment with Ovulen 50 (ethinyl oestradiol 0.05 mg, ethinodiol diacetate 1 mg). Ovulen 50 administration led to a fall in serum folate levels which occurred very rapidly during the first 6 months and more slowly thereafter, stabilizing at 2.2 ng/ml in women of very low economic status and at 2.9 ng/ml in the more privileged. There was a steady fall in serum folate concentrations during pregnancy, the levels at the end of pregnancy being higher than those in women under OC treatment for 9 months. The need for folate supplementation during OC treatment is stressed.