The association between sex hormones and chronic headache has been the subject of a good deal of speculation. Headache is predicted to improve during pregnancy, when estrogen levels rise steadily until delivery. Retrospective studies have suggested that women with a history of migraines do tend to report decreases in headache activity with pregnancy. The purpose of this naturalistic study was to examine changes in headache that may occur during pregnancy and postpartum in women complaining of migraine, tension-type, or combined migraine and tension-type headaches in a prospective design. Thirty women recorded their headaches daily throughout pregnancy and up to 12 weeks postpartum. Results based on these ratings demonstrated a nonsignificant trend for headache to decrease throughout pregnancy and to increase during the birth week. Headache patterns varied slightly depending on headache diagnosis and parity. Contrary to previous retrospective study reports, migraine sufferers demonstrated an increase in headache in the third trimester. In addition, there was a tendency in multiparous women for headaches to increase in the third trimester, whereas primiparous women reported less headache activity throughout pregnancy and the postpartum.