Severe headache in pregnant women: When to worry

"Headaches during pregnancy are quite common, but it is not always easy to distinguish between a recurring, preexisting migraine condition and a headache caused by a pregnancy complication," said lead author Matthew S. Robbins, M.D., director of inpatient services at Montefiore Headache Center, chief of neurology at Jack D. Weiler Hospital of Montefiore, and associate professor of clinical neurology at Einstein. "Our study suggests that physicians should pay close attention when a pregnant woman presents with a severe headache, especially if she has elevated blood pressure or lack of past headache history. Those patients should be referred immediately for neuroimaging and monitoring for preeclampsia."

Preeclampsia (previously called toxemia) typically occurs during the second or third trimester of pregnancy and may be related to an abnormal interaction of blood vessels that supply the placenta. Symptoms and signs can include high blood pressure, headaches, blurry vision, or abdominal pain, although some patients may have no symptoms. Depending on the severity and the age of the fetus, treatment ranges from bed rest for mild preeclampsia to premature delivery if the condition is severe.

Dr. Robbins and colleagues analyzed records of every pregnant woman with headache who had been referred for a neurological consultation at Weiler Hospital over a five-year period. The study involved 140 women with an average age of 29. A large majority of the patients were Hispanic or African-American, reflecting the makeup of the Bronx population.

Most (91) of the 140 women had primary headaches, 90 percent of which were migraines. Among the 49 patients with secondary headache, 51 percent were diagnosed with pregnancy-related high blood pressure, including the 38 percent of women who had preeclampsia.

The most telling indicator of a secondary headache among pregnant women proved to be high blood pressure. Compared to pregnant women with headache but no high blood pressure, women with headache plus high blood pressure faced a 17-fold increased likelihood that their headaches were caused by some other condition. "In most of these patients, their elevated blood pressure was driven by preeclampsia," said Dr. Robbins.

The researchers found that another red flag for a headache that should be taken seriously was lack of a previous history of headache, which was associated with a five-fold increased likelihood that the headache was secondary to something else. Other warning signs were fever, seizures, and headaches in the absence of phonophobia (sound sensitivity) and psychiatric problems.