My period is pretty reliable, but last year, shortly after I moved to the Colorado Rockies, my cycle became unpredictable. It was still in the normal range, but it started coming way earlier than I was used to, with a couple months where it was a week late.

Research shows that living high above sea level — my home is at 9,000 feet — can cause a woman to ovulate earlier. If I were 25, I’d blame my menstrual changes on stress. But I’m heading into my late 30s, so I wondered: are my ovaries just getting old?

Living and exercising at high altitude, where less oxygen is available, is a physiological stressor. This could be the culprit of my menstrual irregularities, but age mixed with life changes — like adapting to a new city or job — could also affect how well ovaries function, says Dr. JoAnn Pinkerton, a gynecologist and the executive director of the North American Menopause Society.  

“As you age and you have less ovarian reserves, you become more sensitive to hormonal fluctuations, and so you may not cope as well [to stress],” says Dr. Pinkerton, a professor of obstetrics and gynecology at the University of Virginia.

This could translate into worsening PMS, more irritability, irregular cycles, and more sleep disturbances, she says. These changes could then affect both your work and personal relationships, resulting in even more stress on the body.

So how does age affect your cycle?
Perimenopause is the time period before menopause when you’ve gone a full year without a period. It usually starts after 40 — with menopause happening around 51 — but it can begin in your 30s, says Dr. Pinkerton.

This transition phase is hard to diagnose because hormones change during the cycle, says Dr. Pinkerton. As hormones fluctuate with age, you might have a 21-day cycle, a 28-day cycle, and then a 36-day cycle, she says.

Strong signs that warrant a trip to your gynecologist include a cycle shorter than 21 days, skipping your period for three or more months, and having hot flashes. Less clear symptoms (that could creep up in your 30s) include bloating, brain fog, mood changes, and a worsening of PMS symptoms before your period. But the fun doesn’t stop there. Weight gain, libido changes, swelling of the feet and ankles, and migraines can all herald the beginning of perimenopause, says Dr. Pinkerton.

But is it just stress?
Physical and emotional strain can definitely cause perimenopause-type symptoms, says Dr. Pinkerton. When her patients with normal blood work complain of menstrual disturbances or worsening PMS, she urges them to take a look at their stress load and find ways to take better care of themselves as a way to get their cycle back on track.

“I’ll say, ‘Let’s work on healthy eating, decreasing stress to see if we can get that ovary to start functioning normally’,” says Dr. Pinkerton.

And while it’s somewhat easy to notice if you’re working too much or not sleeping enough, some problems can be harder to pinpoint, says Dr. Pinkerton. Make sure to take a look at all of your responsibilities, including those for partners, siblings, children, and parents.

“Many women are notorious for taking care of everyone else except for themselves,” she says. “We really think that we can do everything and we can’t, at least not all at the same time.”

When to talk to your doctor
If you’re concerned about your cycle changes, talk with your gynecologist to see what’s going on. There are therapeutic and medical options that can help with symptoms like breast tenderness, migraines, sleep disturbances, depression, or bleeding issues, says Dr. Pinkerton. Every woman will experience the end of her reproductive life differently, but a knowledgeable doctor can help you tackle each one individually.

Keri Wiginton is a writer and photographer focusing on issues related to women's health, mental well-being, and feminism. Her work has appeared in the Chicago Tribune, Washington Post, Austin-American Statesman, Tampa Bay Times and Houston Chronicle. Follow her work at www.keriwiginton.com or on Twitter at @keriphoto.