There are many reasons a teen's period might be irregular, and most of them are completely benign.

• Hormonal immaturity is the most common reason. During the first one to three years after a first period, the hypothalamus, pituitary gland, and ovaries, which are the three key players in regulating the menstrual cycle, are still learning to work together. This often results in unpredictable cycles.
• Stress has a significant impact on hormones. Academic pressure, social challenges, family conflict, and even exciting life changes can all disrupt the menstrual cycle.
• Significant changes in weight can affect hormone levels. Both significant weight loss and weight gain can interfere with the regularity of periods.
• Intense exercise and a very low body fat percentage, which are common in athletes in certain sports, can cause periods to become irregular or stop altogether. This is something worth discussing with a healthcare provider.
• Underlying health conditions can also cause menstrual irregularity. Polycystic ovary syndrome (PCOS) is one of the more common conditions that affects teens and can cause irregular or missed periods, along with other symptoms. Thyroid disorders and other hormonal conditions are also possibilities worth ruling out.

Because every teen's body is different, there's a wide range of what can be considered normal during adolescence. Here's a general guide:

• In the first year or two after a first period, cycles may range anywhere from 21 to 45 days. Periods lasting anywhere from 2 to 7 days are generally considered within range. It's normal for some months to be skipped entirely during this early phase.
• Over time, cycles typically become more regular. By two to three years after the first period, most teens have cycles that fall within the adult range of 21 to 35 days.
• Flow varies, too. Light periods, moderate periods, and heavier periods are all normal, depending on the individual. However, a period that soaks through a pad or tampon every hour for several hours in a row is considered heavy and worth discussing with a provider.
• Mild cramps around the time of a period are common. Severe cramping that disrupts daily activities is worth mentioning to a healthcare provider.

While irregularity is common in teens, certain patterns or symptoms are worth discussing with a healthcare provider:

• Periods that have never occurred by age 15 (this is called primary amenorrhea)
• Periods that were regular and then stopped for three or more consecutive months (outside of pregnancy)
• Cycles that are consistently shorter than 21 days or longer than 45 days
• Periods that last longer than 7 days
• Very heavy bleeding, such as soaking through a pad or tampon every hour for more than a few hours in a row
• Severe cramping that interferes with school, sports, or daily life
• Spotting or bleeding between periods regularly
• Other symptoms alongside irregular periods, such as significant acne, unusual hair growth on the face or body, or unexpected weight changes

These symptoms don't automatically indicate a serious problem, but they're worth bringing to a healthcare provider who can evaluate the full picture.

The connection between stress and menstrual irregularity is very real, and it's one that many teens and their parents don't fully appreciate.

The brain and the reproductive system communicate through a network of hormonal signals. When the body experiences significant physical or emotional stress, the brain can essentially "put the brakes" on certain hormonal signals, including those that regulate ovulation and the menstrual cycle. This is a survival mechanism, not a flaw.

For teens navigating exam season, a difficult friendship, a move, or family changes, it's not unusual to see their cycle become unpredictable. Typically, once the stressor resolves, the cycle returns to its prior pattern.

However, chronic stress or stress combined with other factors like significant weight changes or intense exercise can lead to more prolonged irregularity that deserves medical attention.

Polycystic ovary syndrome, commonly known as PCOS, is a hormonal condition that can cause irregular or missed periods in teens. It's one of the more common reasons a healthcare provider might investigate when menstrual irregularity is persistent.

In PCOS, the ovaries produce higher levels of androgens (often called male hormones, though everyone produces them) than typical. This can interfere with ovulation and lead to irregular cycles. Other symptoms that sometimes accompany PCOS include:

• Acne that doesn't respond well to typical care
• Excess hair growth on the face, chest, or back
• Thinning hair on the scalp
• Weight gain, particularly around the midsection
• Difficulty managing weight

It's important to note that not everyone with PCOS has all of these symptoms, and having some of them doesn't necessarily mean a teen has PCOS. Diagnosis requires evaluation by a healthcare provider.

Talking about periods can feel awkward, but it's genuinely important. A healthcare provider is a safe, nonjudgmental resource for any questions or concerns about menstrual health.

Consider making an appointment if:

• Your teen's period hasn't started by age 15
• Cycles have been irregular for more than two to three years after the first period
• Periods have stopped for three or more months in a row and pregnancy is not a factor
• Cramping is severe enough to miss school or daily activities
• Your teen is experiencing very heavy bleeding
• There are other symptoms alongside irregularity, like significant acne, unusual hair growth, or unexpected weight changes
• Your teen has concerns or anxiety about their cycle that would benefit from professional reassurance

Menstrual health is part of overall health, and there's no question too small or too personal to bring to a provider.