For many women who suffer from migraines, pregnancy can be a period of relief from their headaches. Studies have found that preexisting migraines diminish or disappear in 42% to 98% of pregnant women. However, new, persistent, or worsening migraines during pregnancy can signal a serious problem that could result in a stroke. A study published in the March 2009 issue of the British Medical Journal (BMJ) stroke found that migraine was associated with a 17-fold increase in pregnancy-related stroke.

A stroke or “brain attack” occurs when the flow of blood to the brain is disrupted either by a blockage (an ischemic stoke) or by bleeding in the brain (a Hemorrhagic stroke). When either of these things happen brain cells begin to die, and brain damage occurs. For young women, stroke is a relatively rare phenomenon, occurring in fewer than 11 per 100,000 women.

Pregnant women, however, have a three to thirteen-fold increase in their risk of developing a stroke. Risk factors for pregnancy-related stroke include, but are not limited to:

• older maternal age
• high blood pressure
• vasoreactivity (i.e., changes in cardiac output)
• heart disease
• smoking
• diabetes
• alcohol and substance abuse
• caesarean section
• abnormal blood clotting
• multiple gestations (e.g., twins, triplets, etc.)
• history of migraine headaches

Genetics may play a role in the relationship between migraine and pregnancy-related stroke. Studies have shown that some women with migraines also have mutations in the genes that regulate blood-clotting factors. Abnormal clotting factors can lead to the formation of blood clots in the veins or lungs. These blood clots interrupt the flow of blood to the brain and cause an ischemic stroke.

The BMJ study also found that women with peripartum migraines (migraine before, during and/or after delivery) were twice as likely to have a diagnosis of preeclampsia, a potentially life-threatening condition characterized by high blood pressure and the presence of protein in the urine. Both migraines and preeclampsia are characterized by changes in vasoreactivity.

What does this mean for a pregnant woman with either a history of migraine or new onset of migraine with her pregnancy? More research is needed to fully understand the risks of migraine during pregnancy. In the meantime, pregnant women should make their doctors aware of their history of migraines. Abnormal clotting factors can be mediated with blood thinners and pregnant women with migraines can be monitored closely for signs of preeclampsia.

For women who do suffer a pregnancy-related stroke, there is no data to suggest a risk of recurrent stroke in subsequent pregnancies. However, women who have had a stroke and are contemplating another pregnancy should be assessed for treatable risk factors.

References
Adeney, K. L., & Williams, M. A. (2006 May) Migraine headaches and preeclampsia: an epidemiologic review. Headache 46, 794-803.

Allais, G., Castagnoli Gabellari, I., Airola, G., Schiapparelli, P., Terzi, M. G., Mana, O., Benedetto, C. (2007 May) Is migraine a risk factor in pregnancy? Neurol Sci 28 Suppl 2, S184-7.

Bushnell, C. D., Jamison, M., James, A. H. (2009) Migraines during pregnancy linked to stroke and vascular diseases: population based case-control study. BMJ 338, b664.

Davie, C. A., O’Brien, P. (2008 Mar) Stroke and pregnancy. J Neurol Neurosurg Psychiatry 79, 240-245.

James, A. H., Bushnell, C. D., Jamison, M. G., Myers, E. R. (2005 Sep) Incidence and risk factors for stroke in pregnancy and the puerperium. Obstet Gynecol 106, 509-516.

Treadwell, S. D., Thanvi, B., Robinson, T. G. (2008 May) Stroke in pregnancy and the puerperium. Postgrad Med J 84, 238-245.

Source: Society for Women’s Health Research (SWHR)