What's normal, and when to get help

What's normal

• Cycle length: the average is 28 days. Regular cycles anywhere from 21 to 35 days are normal.^1,2 The NHS in the UK gives the same range.³
• Period length: most periods last 3 to 7 days.² ACOG, the U.S. group of OB-GYNs, says a normal period lasts up to 7 days.¹
• A personal normal: the amount of bleeding can vary a bit from cycle to cycle, and what is normal for one person can differ from another.
• In the first years: cycles are often longer and less regular. For teens, ACOG says cycles of 21 to 45 days are typical, and it can take up to 3 years for cycles to settle.^2,4

Myth: Every cycle is 28 days, and ovulation happens on day 14.

A lot of us learned this, and it's an easy rule to remember. It's really an average. Regular cycles anywhere from 21 to 35 days are normal,^1,2,3 and the time between ovulation and the next period can range from about a week to more than two weeks.⁵ So ovulation moves with the cycle, and it may fall on a different day than a friend's.

Myth: If your period comes every month, you ovulated.

It's a very reasonable assumption, and many of us were never told otherwise. A period can happen without an egg being released. In one small study of women who all had regular periods, only 45% of the cycles of women who exercised regularly showed normal ovulation, compared with 90% in women who didn't exercise.⁶ Dr. Stacy Sims, a researcher who studies women's training, says a normal-looking bleed can happen without ovulation when someone is under stress, training hard, traveling, or not eating enough.⁷

That study was small (35 women) and from 1998. If you're trying to get pregnant, or your cycles change, tell your doctor.

Track your cycle

Tracking your cycle shows you your own pattern, helps you know when to expect the next period, and gives your doctor useful information. ACOG calls the menstrual cycle a "vital sign" because it can tell you something about your overall health.⁴

1. Mark the first day of your period on a calendar. That is day 1.
2. Mark each day you bleed.
3. When bleeding starts again, mark day 1 again. Count the days between each day 1 to get your cycle length.

A calendar works, and so do period-tracking apps. If you also notice changes like mood, sleep or cravings, write those down too. A pattern is easier to see, and easier to explain to a doctor.

Infections that change discharge

Three common infections can change vaginal discharge. They don't all spread the same way, and an infection doesn't always mean it was caught from a partner.

• Bacterial vaginosis (BV) is an imbalance of the bacteria that normally live in the vagina. It is a common cause of unusual discharge, often with a strong fishy smell. About half of people with BV have no symptoms.⁸ It isn't classed as an STI, but sex can trigger it, and people who have never had sex can get it. Other risk factors include a new partner, an IUD and perfumed products.⁸
• Thrush (a vaginal yeast infection) is caused by a fungus called candida, which normally lives on the skin. Typical signs are thick white discharge like cottage cheese that usually doesn't smell, plus itching and soreness.⁹ It isn't an STI. Common triggers are antibiotics, pregnancy, poorly controlled diabetes, a weakened immune system and hormone replacement therapy.⁹
• Trichomoniasis is an STI, passed on through vaginal sex, genital skin-to-skin contact or shared sex toys. It can cause yellowish-green discharge that sometimes smells fishy, itching and pain when peeing, but many people have no symptoms.¹⁰ Sexual partners need treatment too.¹⁰

So BV and thrush often follow a change in the body's balance, like a course of antibiotics, rather than something a partner passed on. Treatment is different for each: antibiotics for BV and trichomoniasis, antifungal medicine for thrush.^8,9,10 That is a reason to get checked instead of guessing. BV or thrush that comes back four or more times a year can need longer treatment.^8,9

When to talk to a doctor

Contact a healthcare provider if:^1,2,4

• you haven't had your first period by age 15
• you don't get a period for 3 months or longer
• your cycles are shorter than 21 days or longer than 35 days
• your period lasts longer than 7 days
• you're bleeding much more or much less than usual
• you soak through a pad or tampon every hour or two
• you have severe pain during your period
• you bleed between periods
• your discharge changes in colour, smell or texture, or you have itching or soreness¹¹
• you think you might be pregnant

Get care now: if you're soaking a pad or tampon every hour for more than 2 hours in a row and you also have chest pain, shortness of breath, or feel lightheaded or dizzy, get emergency medical care right away.¹