How Common Is It to Have No Pregnancy Symptoms? (Video)

A small percentage of women have made it to 20 weeks with presumably no pregnancy symptoms. Doctors explain how.

Imagine finding out you're pregnant—and that you conceived 5 months ago. It sounds incredible, but it's possible, says Jane van Dis, M.D., OB-GYN and medical director at Maven Clinic, the largest telemedicine network in women's and family health.

"The patients I've cared for who've experienced this almost always report that their periods are irregular. They're not surprised or investigating if, for instance, they've missed their period for two, three, or even four months," Dr. van Dis explains.

According to research in the Journal of the Royal Society of Medicine, 1 in 475 women may not realize they're pregnant until 20 weeks, and another 1 in 2,500 women only learn they're pregnant once they're in labor.

It's not uncommon to have no pregnancy symptoms in the four to six weeks after your last period. Doctors date pregnancy to the first day of the last menstrual period. "This number is off by two weeks because most women know the day of their period but they don't know the day of conception," says Dr. van Dis.

Woman having ultrasound scan
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The first symptoms usually show up about 14 days after the fertilized egg implants into the uterine wall, and might include nausea, breast tenderness, and changes in nipple color. This could be days or weeks after a woman expects her period to start. In fact, almost 30 percent of women surveyed by the American Pregnancy Association said they missed their period before any pregnancy symptoms began.

"Most pregnancy symptoms will present themselves within the first six weeks," says Kecia Gaither, M.D., MPH, FACOG, double board-certified OB-GYN and director of perinatal services at NYC Health and Hospitals, Lincoln.

No Pregnancy Symptoms at 20 Weeks

For women with irregular menstrual cycles, though, a missed period doesn't always signal pregnancy. And someone who doesn't think she's pregnant might attribute her symptoms to other causes (blaming constipation and nausea on gastrointestinal issues, for example).

"Women with polycystic ovary syndrome (PCOS) oftentimes will have months on end without a period," says Dr. van Dis. "On the flip side, some women have bleeding on and off throughout the first trimester and even into the second trimester. It's a complication and symptom of pregnancy, but if she has no other symptoms of pregnancy, she may attribute the bleeding to an irregular cycle."

A menstrual cycle is an important vital sign, says Dr. van Dis. Providing your doctor with a thorough history of your menstrual cycle offers insight into your reproductive organs and hormonal status.

Can You Be Pregnant and Not Know It?

What about the rare 1 in 2,500 women who find out they're pregnant only once they're in labor, who, presumably, had no pregnancy symptoms?

"There are indeed women who 'didn't know they were pregnant'—these women have underlying, often undiagnosed psychological issues," says Dr. Gaither.

Pregnancy denial is a condition in which a pregnant woman does not notice that she's pregnant and lacks "objective perceptions of the pregnancy," according to the scientific journal BMC Psychology.

Denial of pregnancy can happen with women who don't want to be pregnant, including teenagers, people with addiction, and those who, for various reasons, believe they're not ready to have a child.

"I haven't done a lot of research into it but it seems to me, for someone to not know they're pregnant until labor, there's a mixture of physiology—wherein there really were very few or no signs of pregnancy—and mental health issues," says Dr. van Dis.

"There is such a distinct difference between a belly full of food or bloating in the intestines and the belly that develops over the course of pregnancy because there's a gestating baby inside," Dr. van Dis adds.

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