Is Pregnancy Possible During Perimenopause?

While fertility gradually diminishes as you age, women at midlife are still able to conceive—whether they want to or not.

According to the National Center for Health Statistics, there were 840 births to women 50 years and over in 2017. In addition, the birth rate for women aged 45 and over was 0.9 births per 1,000 women, and for women aged 50 to 54 it was 0.8 births per 10,000 women. While these are small numbers, it indicates that pregnancy can happen in midlife (when many erroneously assume naturally conceived pregnancy is no longer possible.) 

Many other questions surround the biological transition from child-bearing years to post-menopause.

What Is Perimenopause?

Perimenopause refers to the months or years leading up to menopause, which is the permanent cessation of menstrual periods that occurs at an average age of 51. Perimenopause (also called menopausal transition) can last just a few months or for up to 14 years, beginning as early as a woman’s late thirties. Periods tend to become irregular during perimenopause, and women often experience hot flashes, mood swings, vaginal dryness, fatigue, or difficulty sleeping.

Are You Pregnant or Perimenopausal?

Healthcare providers may perform blood tests to determine if a woman who has skipped one or more periods is either pregnant or approaching menopause. These tests measure the levels of certain hormones, some of which signal pregnancy (a positive hCG test) and others that can provide clues about a woman's ovarian function or decline.

FSH, or follicle-stimulating hormone, is produced in the brain and increases as the number of eggs produced by a woman's ovaries decreases. A consistently elevated FSH level along with the ending of menstrual cycles for 12 months supports a diagnosis of menopause.

That being said, FSH levels fluctuate during perimenopause—so it is difficult to interpret a single number. This is why an FSH blood or urine level cannot accurately diagnosis perimenopause or menopause. It is simply another piece of the pie. A women's symptoms and menstrual history are also needed to put the whole picture together.

How Do You Know If You're Still Fertile?

You must assume you're still capable of conceiving until menopause is complete, which has not occurred until menstrual periods have ceased for 12 full months. “Menopause is not an on-off switch,” says Dr. Stuenkel. “But many women don’t really understand exactly what’s happening.”

Ovarian function waxes and wanes in perimenopause, meaning that a woman may release an egg some months but not others. Additionally, body levels of estrogen, progesterone, and other hormones tend to be erratic during this time and egg quality decreases, all contributing to more than a 50 percent decrease in fertility among women 40 and over compared to younger women. But natural conception is still possible—if remote—for women until their mid-fifties.

Do You Still Need Contraception?

Yes. Unless you want to conceive during perimenopause, contraception is essential until you haven’t had a period for a full year. “If you really want to be sure,” Dr. Stuenkel says, “it would be best to continue [using contraception].” A 2015 review found that 75% of pregnancies in women over age 40 were unplanned.

What Are the Pregnancy Risks During Perimenopause?

The possible hazards are many for both mother and baby. Miscarriage increases among older mothers because of lower-quality eggs, variable hormones, and uterine changes. Poor egg quality also ups the chances for birth defects such as Down syndrome, which is caused by an error in cell division which produces an extra chromosome.

Other risks to the baby include premature birth (anytime before 37 weeks of gestation), which is linked to a host of complications ranging from cerebral palsy to learning and developmental disabilities.

The rigors of pregnancy are also harder on older mothers, who suffer more than their younger counterparts from complications such as high blood pressure, strokes, seizures, gestational diabetes, and heart problems.

What If You're in Perimenopause and Still Want to Have a Baby?

Act quickly. Beyond that, consult your healthcare provider if you haven’t conceived after six months of unprotected intercourse (one year is the recommendation for women 35 years of age and younger). The good news is that there are a number of options available to help couples struggling with conceiving a child.