Why Has My Period Changed?

Birth control pills use hormones to regulate ovulation and switching brands or types may affect your menstrual cycle. Tracking your period can help you understand what’s normal for you, time ovulation and identify important changes such as a missed period or unpredictable menstrual bleeding. While menstrual cycle irregularities usually aren’t serious, sometimes they can signal health problems.

What causes menstrual cycle irregularities?

There are a number of different causes that can affect your period:

  • Pregnancy or breast-feeding. A missed period is the most certain symptom of pregnancy. Breastfeeding typically delays the return of menstruation after pregnancy.
  • Polycystic ovary syndrome (PCOS). This is a hormonal disorder common in women in their reproductive years. Infrequent, irregular, or absent menstrual cycles or abnormally heavy periods are symptoms.
  • Premature ovarian failure. Premature ovarian failure refers to the loss of normal ovarian function before age 40. Women who have premature ovarian failure — also known as primary ovarian insufficiency — might have irregular or occasional periods for years.
  • Pelvic inflammatory disease (PID). This infection of the reproductive organs can cause irregular menstrual bleeding.
  • Uterine fibroids. These noncancerous growths of the uterus can cause heavy menstrual periods and prolonged menstrual periods.
  • Extreme weight loss or excessive exercising. Extreme weight loss and increased physical activity can disrupt menstruation.

Did My New Birth Control Pill Change My Period?

After using one birth control type or brand for a while your body adjusts to the hormones and you establish a more regular menstrual cycle. When changing to a new birth control pill, or even from a generic to name brand or vice versa, your menstrual cycle may readjust. There is a good chance your period could be delayed or come sooner than expected. Some women even experience cessation of the menstruation for one or two cycles while her body adjusts.

Here are some changes you can expect when switching from one type of pill to another:

• Delayed periods
• Absent periods
• Heavier periods
• Lighter periods
• Longer periods
• Shorter periods
• Spotting in between periods

What can I do to prevent menstrual irregularities?

Some period irregularities can’t be prevented. Birth control pills can help regulate menstrual cycles for some women.

In addition, consult your health care provider if:

  • Your periods suddenly stop for more than 90 days — and you’re not pregnant
  • Your periods become erratic after having been regular
  • You bleed for more than seven days
  • You bleed more heavily than usual or soak through more than one pad or tampon every hour or two
  • Your periods are less than 21 days or more than 35 days apart
  • You bleed between periods
  • You develop severe pain during your period
  • You suddenly get a fever and feel sick after using tampons


Mayo Clinic: Menstrual cycle: What’s normal, what’s not

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