Headaches after childbirth.

71 women were examined daily for the presence of headache in their first post partum week. Post natal headache (PNH) occurred in 27, (39%) of the women and was most frequent on days 4-6 post partum. PNH was significantly associated with a previous or family history of migraine and pre-menstrual migraine. Although 83% of those with PNH had a migraine diathesis, they did not describe their headache as one of their usual migraines as it was considerably milder. Headaches were more frequent among multigravida but as rather more multigravida had a previous migraine diathesis this may reflect a sampling bias. PNH subjects had significantly more tension and depression suggesting that at least some PNH may be tension headache. Around 3 or 4 days post partum, women began to lose weight and the onset of headache often coincided with the start of this weight loss. 12 women with, and 12 without PNH took part in a metabolic study, and collected sequential 24 h urine samples from days 2-7 post partum. Potassium and oestrogen excretion were increased on day 3, and progesterone on days 3, 4 and 5. Differences in the excretion pattern of these hormones might reflect small changes in renal function and further work measuring plasma hormone levels could help to clarify this. PNH, like pre-menstrual headache and pill withdrawal headache may represent a further example of the triggering effect that a fall in sex hormone level has on the migraine diathesis.