When Does PMS Occur?

As noted previously, PMS symptoms appear in the second half of a woman’s menstrual cycle, most likely because of the sharp drop in progesterone levels. But, as with the length of a normal menstrual cycle, variation is normal.

In the usual scenario, PMS symptoms appear seven to ten days before menstruation and get progressively worse until the day the woman gets her period, at which point they either cease immediately or taper off more gradually (usually within four days of getting a period). A small number of women, between 5 and 10 percent, experience a short burst of PMS symptoms around ovulation. PMS experts believe this may be related to the fall in estrogen that occurs around the middle of a woman’s menstrual cycle.


Hormones and chemical transmitters in the brain, called neurotransmitters, perform interrelated functions in PMS. The hormones estrogen and progesterone regulate the menstrual cycle, and the neurotransmitters serotonin and gamma-aminobutyric acid (GABA) protect against PMS symptoms.

Some women complain of symptoms that begin shortly after ovulation and continue throughout their periods. Given that ovulation can occur two weeks before a woman’s period and a period last eight days, this means three full weeks of PMS! In some women, experts say, this near-constant experience of PMS gets progressively worse and can appear to be a mood disorder.


Estrogen is a hormone compound. Three hormones make up estrogen: estradiol, estriol, and estrone. Estradiol predominates in women during their reproductive years, while postmenopausal women have more estrone in their bodies.

In another interesting twist, PMS also appears to occur frequently and more severely in women who are 30 or older. Many women complain that their symptoms get progressively worse with age. However, given that PMS can strike a menstruating woman of any age—usually starting anywhere from about two years after a girl starts menstruating, or about age 14, all the way through to menopause—this increase in severity has some experts puzzled.


The mid-cycle drop in estradiol is thought to cause PMS symptoms around ovulation in some women.

One theory is that women 40 and older are really experiencing some of the symptoms of menopause or perimenopause but confuse them with PMS. Another is that older women see health-care providers for non-pregnancy-related reasons more frequently and therefore have more opportunities to seek help for PMS.

Finally, a third theory is that the emotional and mood swings so common with PMS are written off in teenagers as part of adolescence. The truth of the matter is that there's not enough information about PMS to tell for certain why older women are more likely to have more severe PMS.

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