Uh-oh. Periods getting shorter?

why periods are getting shorter

There’s a wide range of what’s normal when it comes to menstrual cycles. But too many variations from your normal, or the kind of cycle you’re used to, may indicate some changes happening in your body and shouldn’t be brushed off.

First, some basics about your cycle

Let’s clear up some confusion: the day you get your period and start to bleed is the first day of your cycle. Usually, you hear menstrual cycles last about 28 days. But anywhere from 25 to 35 days can be considered normal. During that time, your body goes through three phases: follicular, ovulation, and luteal.

What your hormones do in each phase of your cycle

Menstruating regularly requires a delicate dance of hormones. The rise and fall of estrogen and progesterone throughout your cycle are guided by two other hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The pituitary gland releases LH and FSH..

  • Follicular phase. On day one of your period, you start this phase. Then, after you finish menstruating, follicle-stimulating hormone (FSH) rises. About 3 to 30 follicles form on the surface of the ovary. Each follicle contains an egg. As you move through this stage, FSH begins to drop. Only one follicle and egg continue to develop. Estrogen rises.
  • Ovulation. Luteinizing hormone (LH) begins to increase. Then, the follicle that developed during the follicular phase ruptures and releases the egg. Estrogen declines, and progesterone begins to rise.  
  • Luteal phase. After ovulation, the luteal phase begins. Having done their jobs, LH and FSH decline. A corpus luteum is formed from the ruptured follicle, and that corpus luteum triggers an increase in progesterone. The uterus lining thickens. At the end of this phase, progesterone sharply drops.

When your periods get shorter

Menstruation’s often an indicator of what’s going on in the body. Any alterations in your cycle deserve attention. Common changes include heavier or lighter flow, greater or fewer days between periods, skipped periods, and how long your period lasts. Bleeding from 2 to 7 days is normal. So, it’s important to notice what’s different for you and your body and record those changes.

If you only need a cup or tampon for a day or two and then your period disappears, talk to your provider. Here are a few reasons why your cycle might be getting shorter.


Later-in-life surprise babies aren’t all that uncommon. That’s because women in perimenopause can still get pregnant, even with irregular or skipped periods. When conception occurs, it’s possible to get some light bleeding that seems like a period. This is called implantation bleeding. Usually, the blood is light pink or brownish.


Ahhh, stress. When you have a bout where you feel overwhelmed or over-anxious, your body ups adrenaline to help you cope. After a while, it increases cortisol. To meet the increased demand, your body may use some of the sex hormone progesterone. Without enough progesterone, the uterine lining may not thicken enough to shed.


Progesterone, one of the hormones needed to menstruate regularly, starts to decline as early as your thirties. In the time leading up to menopause, many women may experience symptoms of low progesterone, as well as low estrogen. If this is the case, one of the things you may deal with are irregular, light, or periods that shorten by several days.

Polycystic Ovarian Syndrome (PCOS)

In PCOS, levels of androgen hormones (like testosterone) are higher than they should be. Often times, women with PCOS also struggle with insulin issues. Both of these factors can throw off your monthly cycle, causing skipped or shortened periods.


Thyroid hormones influence your cycle. Too little hormone, or hypothyroidism, usually causes periods to become longer and heavier. However, hyperthyroidism (too much thyroid hormone) can result in shorter, lighter bleeding.