Mache Seibel, MD, OB-GYN, author of The Estrogen Fix and Working Through Menopause, is trying to change that by shedding light on all things perimenopause, as well as on menopause itself. Read on to find out what he told Best Life about this inevitable, and completely normal, life stage that anyone with a uterus can expect to face, if they haven’t already. READ THIS NEXT: Stacy London Says She’s Fighting Back Against This Health “Crisis” in Exclusive Interview.

You may think of perimenopause as something that only happens to older people, but it can start much earlier than you think: “The average age of menopause in the US is 51,” says Seibel. “But five to ten percent of women enter menopause before age 45; one percent before age 40. So, perimenopause can possibly begin as early as mid to late 30s,” he explains. And with many people putting off having children until their late 30s, or even early 40s, this can come as an unwelcome surprise. “Many women struggling with infertility are, in fact, approaching or in perimenopause,” Seibel notes. So what exactly are the symptoms of perimenopause? “The most common symptoms are mood changes, menstrual cycle changes, less sexual desire, anxiety and sadness, or mild depression,” says Seibel, noting that the same symptoms can also be due to anxiety or depression unrelated to the menstrual cycle. “Those symptoms are inseparable from perimenopause. But if [someone has] suddenly or recently gotten more anxious and depressed, something must be changing, and the more common thing is perimenopause,” he explains. One of the more frustrating things about perimenopause is that it’s virtually impossible to know for sure whether you’re in it. “There is no marker that is absolute,” says Seibel. “A slightly elevated follicle-stimulating hormone (FSH) level is the best indicator. But these values aren’t linear; they can fluctuate up and down… It’s like the stock market,” he explains. That said, getting a blood test to determine your FSH level can be helpful. “A blood test for FSH is not diagnostic, but when it begins to be above 15 miU/ml, perimenopause is likely in process.” For more health news sent directly to your inbox, sign up for our daily newsletter. Anyone who has experienced perimenopause can tell you that it’s no picnic. Moodiness, a period that plays peek-a-boo, and a decreased libido aren’t fun—and to add insult to injury, when you are feeling frisky, you may realize that sex is becoming uncomfortable. “Vaginal dryness is also a common symptom of perimenopause,” Seibel says, adding that " over-the-counter remedies, like Replens products, can be very helpful.“ae0fcc31ae342fd3a1346ebb1f342fcb So how long can people expect this transition, which they may not even know they’re in until after the fact, to last? “Perimenopause can last up to 10 years,” says Seibel. “The two-to-three years before menopause (which they would only know in retrospect) are usually the worst symptoms. In fact, many women think perimenopause is menopause due to the worsening of symptoms.” For many people, one of the benefits of being in menopause—which happens once you’ve gone a full year without having a period—is that they no longer have to worry about the risk of pregnancy. However, this is not true of perimenopause. “Fertility is reduced [during perimenopause] but not eliminated,” Seibel explains. “Until they have gone 12 months without a period… [people need to use] birth control if they are sexually active.” Another important point? People in perimenopause or menopause still need to practice safe sex. “Using birth control pills doesn’t protect you from sexually transmitted infections (STIs),” Seibel points out. In fact, STIs are on the rise in older people, Harvard Health reports. If you have questions about perimenopause, menopause, your ability to get pregnant, or whether you’re at risk of contracting an STI, speak with your healthcare provider.