Migraine history may be marker of pregnancy risks – Harvard Gazette

Researchers at Brigham and Women’s Hospital have found that women with prepregnancy migraine had a greater risk of complications, including preterm delivery, gestational hypertension, and pre-eclampsia.

Brigham and Women’s researchers analyzed data from thousands of women from the Nurses’ Health Study II to assess the relationship between migraine and pregnancy complications. The Neurology team reported that migraines diagnosed before pregnancy are linked to adverse outcomes. This suggests that the condition could be a clinical indicator of high obstetric risk.

“Preterm delivery and hypertensive disorders are some of the primary drivers of maternal and infant morbidity and mortality,” said first author Alexandra Purdue-Smithe, associate epidemiologist at Brigham and Women’s Hospital and instructor in medicine at Harvard Medical School. “Our findings suggest that a history of migraine warrants consideration as an important risk factor for these complications and could be useful in flagging women who may benefit from enhanced monitoring during pregnancy.”

Migraine is more common in women than it is in men. It’s two to three times more likely for women to suffer from migraine than for men. Some migraine headaches may be accompanied with aura (5.5%), which is usually a visual disturbance that occurs before the headache starts.

Studies have shown that adverse pregnancy outcomes, migraine and migraine with aura are all associated with higher risks of having a baby and more likely to suffer from ischemic stroke. The risk factors that lead to pregnancy complications could also be attributed to the underlying biology. Only a handful of retrospective or small studies have looked at migraine as a risk factor in pregnancy complications. There have been no prospective studies that looked at the risk of migraine with or without aura.

Purdue-Smithe and colleagues analyzed data from the large, prospective Nurses’ Health Study II, which included 30,555 pregnancies from 19,694 U.S. nurses. Investigators examined the pre-pregnancy self–reported migraine and migraine phenotype (migraine WITH and WITHOUT aura) as well as the incidence of self–reported pregnancy outcomes.

Researchers could adjust for possible confounding factors such as smoking, chronic hypertension, body mass, and other factors due to the large sample size.

Pregnancy migraine was linked to a 17 percent greater risk of preterm birth, 28 percent more gestational hypertension and a 40 percent higher rate pre-eclampsia rate than no migraine. A migraine with aura was associated more with pre-eclampsia risk than migraine without aura. The risk of developing gestational diabetes mellitus or low birth weight was not linked to migraine.

Participants with migraine who took aspirin more than once a week before getting pregnant had a 45 percent reduced chance of having a preterm baby. U.S. Preventive Services Task Force recommends low-dose aspirin for pregnant women at high risk for pre-eclampsia or those with more than one moderate risk factor. Studies have shown that low dose aspirin can also reduce the rate of preterm births. Purdue-Smithe says that migraine is not currently a valid indication for aspirin usage in pregnancy.

“Our findings of reduced risk of preterm delivery among women with migraine who reported regular aspirin use prior to pregnancy suggests that aspirin may also be beneficial for women with migraine. Given the observational nature of our study, and the lack of detailed information on aspirin dosage available in the cohort, clinical trials will be needed to definitively answer this question.”

The study had other limitations. Participants were required to report migraine diagnosis from a physician. The aura was evaluated after the migraine diagnosis as well as after several pregnancies within the cohort. This could have resulted in some reverse causation in studies examining the migraine phenotype. The cohort study is primarily composed of non-Hispanic white people with high socioeconomic status, health literacy, and a relatively low level of generalization.

Disclosures: Information about competing interests and disclosures is available at https://doi.org/10.1212/WNL.0000000000206831. Funding: This research was funded by the National Institutes of Health, U01 CA176726 and HL145386, respectively. Purdue Smithe AC et.al. “Prepregnancy Migraine, Migraine Phenotype, and Risk of Adverse Pregnancy Outcomes” Neurology DOI: 10.1212/WNL.0000000000206831.