Whether you’re dreading or jonesing for the end of your period life, there’s no definitive way to predict when it will naturally happen. But if you’ve got a uterus and ovaries, you’ll likely experience menopause — marked by one year without a period — between 45-55. In general, most females will transition out of fertility around 51, with only about five percent undergoing menopause before 45. While there’s no single factor that will decide your menopausal age, experts say that you can look to your mom and other women in your family for the most reliable gauge of how early or late it may be.

“If I have a patient whose mom went through menopause at 45, then there’s an increased chance they’ll go through menopause early,” says Dr. Kathleen Green, an OBGYN at the University of Florida Health Women’s Center.

While the menstruation history of the females in your family is a good indicator, there are other factors at play. For starters, studies show black and white women go through menopause around the same age. Latinas and native Hawaiians, however, transition a little earlier, and the onset of women of Japanese descent is a little later.

In addition to ethnicity and genetics, there are some lifestyle and medical factors that can affect your ovarian function. Here are five factors that could trigger an earlier menopause.

1. Exposure to smoking

Whether females are smoking cigarettes themselves or they inhale smoke secondhand, tobacco exposure is linked to infertility and earlier menopause. Dr. Green said women who smoke typically go through menopause about two years earlier than average. Research shows the habit is correlated with premature ovarian failure because smoking exposes women to chemicals that accelerate the death of egg cells in the ovaries.

2. Age of first period

Females who start their period when they are 11 or younger — compared to those 12 or 13 — are more likely to experience early or premature menopause, according to one study. (Menopause before a woman is 40 is defined as premature, whereas menopause between 40-45 is called early.) The same research said early menstruating women who hadn’t had kids were twice as likely to experience premature menopause compared to their childbearing counterparts.

3. Being underweight

Compared to women of normal weight, studies show females who are underweight — meaning they have a body mass index (BMI) under 18.5 — have a 30 percent higher chance of going through menopause before they are 45. For those who had a BMI of 17.5 when they were 18, the risk jumps to 50 percent.

4. Cancer treatments

Chemotherapy or radiation treatment can induce medical menopause by causing premature ovarian deficiency. Depending on a patient’s age, the ovaries may or may not recover. However, if young female patients stop getting their periods during treatment, Dr. Green said “most of the time it will come back later on.” No matter the age or sex, she advises any patient undergoing this kind of treatment to talk with a reproductive endocrinologist or fertility specialist about options.

5. Ovary removal

Women who have a bilateral oophorectomy  — removal of both ovaries — experience surgically induced menopause. With no ovaries to produce estrogen, patients will stop having their periods and transition into menopause immediately.

So, how do you know it’s really early menopause?

Certain factors like stress or exercise can mimic perimenopause — the time period leading up to menopause — especially if you’re in your late 30s. But if you’re between 45-55, the most common initial change signaling the end of fertility will be an absent period. And if you’re in your mid-40s and you’ve missed three periods — and there isn’t another medical cause for your menstrual irregularities — Dr. Green said it’s likely you’ll go through menopause in the next few years.

While there is are no diagnostics that can give you a surefire answer about menopause, there are some blood tests that can tell you about your hormonal health. However, menopause before 45 is rare, and most women are still fertile even in their late 30s and early 40s. So if your period gets off schedule or you have symptoms like mood swings and hot flashes, just talk to your doctor. Your gynecologist is there to help.

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.