Women are three times more likely to suffer from migraine than men. This 3 to 1 ratio of women to men does not occur until puberty. Before puberty, boys and girls have a similar rate of migraine attacks. At puberty, the female ovaries begin producing hormones, including estrogen and progesterone. The ups and downs in hormones that occur during the menstrual cycle are considered the main trigger for the increase in migraines in women compared to men.
Hormonal changes occur at menarche (when an adolescent begins menses); during monthly periods often referred to as menstrual cycles; pregnancy; post-partum (after delivery); perimenopause; and menopause. Hormonal changes can also occur when the birth control pill, patch or the contraceptive vaginal ring are used or if hormonal therapy such as estrogen is used for menopausal symptoms.
How do hormones cause migraines?
Estrogen, one of the female hormones produced by the ovary, has well-known effects on the way the brain functions. Estrogen also affects the way pain is perceived. For example the high level of estrogen during pregnancy is thought to help decrease the pain of childbirth. The decrease in estrogen that occurs just before menses is considered to be the main hormonal trigger for menstrual migraine. A landmark study done in the early 70’s looked at a group of women that had migraines with their periods (menstrual migraines). In this study, women were given estrogen by injection late in their cycle just migraines were delayed until the estrogen level dropped. When this same group of women was given an injection of progesterone late in their cycle, their bleeding was delayed but not their menstrual migraine. The results of the study pointed to the drop in estrogen as being the main hormonal trigger for menstrual migraine and not progesterone.
Significantly, during pregnancy when estrogen levels are high, many women experience marked improvement in their migraines. However, at the time of delivery, estrogen levels drop dramatically and often cause a lot of migraines during the post-partum time. During perimenopause, often referred to as the “change before the change”, when hormones are fluctuating dramatically, there is often a worsening of migraines. The typical age of perimenopause is 47-51 but it can last until 55 or when a woman stops having menses. Fortunately, many women experience major improvement of migraine during menopause. Therefore, the ups and downs in hormones, especially estrogen, appear to be a huge trigger for migraine attacks in women. At menopause, when the ovaries stop producing estrogen and progesterone, the hormonal trigger is no longer present from a woman’s own ovaries.
Over 50% of women with migraine experience migraine attacks with menses. If a woman has a migraine during the time frame of 2 days before menses to 3 days into her menses (often called -2 to +3 of the cycle; Day 1=first day of menses) and notices this pattern in at least 2 out of 3 cycles, then she would be considered to have menstrual migraine. Women with menstrual migraine are more likely to suffer from migraine without aura, have more severe and longer-lasting migraines, and suffer more disability with their menstrual migraines than migraines occurring at other times of the month.
Menstrual migraine can be further broken down into menstrual related migraine (MRM) and pure menstrual migraine (PMM). Most women with menstrual migraine have migraines at other times of their cycle from other triggers such as stress or lack of sleep; this group has menstrual related migraine. A smaller number of women experience migraines only with menses and not at any other time of their cycle; these women have pure menstrual migraine. Why is this important? Distinguishing between menstrual related migraine and pure menstrual migraine can help with treatment. Women with pure menstrual migraine can focus on treatment regimens targeted to their menses; women with menstrual related migraine need to be aware of all their triggers and may need a daily preventive treatment plan to help prevent all their migraine attacks.
Keeping a migraine journal is essential to diagnosing menstrual migraine. The first and last day of menses should always be marked on the calendar in addition to listing all headaches. In addition, any change in hormones, including a change in birth control, should always be noted. Some hormonal treatments may help menstrual migraine; some may worsen menstrual migraine.