Chronic headache fluctuates in response to changes in hormonal levels. Headache generally improves with rising estrogen levels, and worsens with falling levels. Headache should, therefore, predictably improve with pregnancy and worsen postpartum. Several retrospective studies have confirmed this pattern. In this study, 49 pregnant women with chronic headache (18 with migraine, 16 with tension-type, and 15 with combined migraine and tension-type) were followed prospectively. Headache activity was recorded daily throughout pregnancy and for 3 months postpartum. Overall, there was a 30% improvement in headache between the second and third trimesters for the entire sample. This was not statistically significant. Headache improved significantly for 41% of the women, with a slightly greater tendency for headache to improve in women with migraine compared to those with tension-type or combined migraine and tension-type headaches. Headache activity was not influenced by history of menstrual migraine, history of headache change with prior pregnancies, parity, or breast-feeding. In general, women reporting headache at the end of their first trimester continued to report headache throughout pregnancy and postpartum.