It happened again last week: a 25-year-old in the U.K. thought she was coming down with the stomach flu…then got the shock of her life when she delivered a baby while sitting on her toilet. And in January, a Massachusetts woman who was rushed to the ER with insane back pain was blown away by the news that she was in labor and about to give birth, as well.
We can understand having no clue about a surprise birthday party. But a surprise full-term baby? Considering all the physical and mental changes that happen to the typical expecting mom over nine months, it’s hard to get how a woman could be in the dark. Turns out, the phenomenon, known as cryptic pregnancy, isn’t so uncommon (it happens often enough to be the basis of a reality show). And it really is possible for some women to go 40 weeks without having a clue they’re carrying a kid. Here’s why.
“Women who are very overweight or obese won’t necessarily see the physical changes that a baby is growing inside them, and the extra fat can insulate her from feeling the baby move and kick,” says Mary Jane Minkin, M.D., clinical professor of ob-gyn at Yale School of Medicine.
If your flow always went MIA and never stuck to a schedule—either because of your own body chemistry or a condition such as Polycystic Ovarian Syndrome (which causes an off-kilter cycle)—you wouldn’t necessarily think that no period equals pregnancy, says Minkin.
While chances are slim that you could get a false negative from a home pregnancy test (Minkin estimates it’s less than a one percent chance), it is possible—especially if you pee on the stick so early on that your body isn’t producing enough of the hormone the test is supposed to detect, if you drink too much water and dilute your urine so that your hormone levels are also diluted, or if you use it wrong. Always do a backup test, and if that comes out negative but your flow isn’t showing up and you detect other early-pregnancy signs like nausea or nipple tenderness, have the doc test you, suggests Minkin.
“It’s normal for the baby to start moving around and kicking in the second trimester, but not all do,” says Minkin. It’s also possible that the baby is moving, but because the placenta is in front of the baby, the pregnant woman doesn’t feel anything, she adds.
In their mid to late 40s, many women experience shifts in their cycles collectively known as perimenopause: irregular periods, a period that stops for months before starting up again, and other body changes such as weight gain and moodiness. These all happen to be signs that a baby is on board, too. “This happened to a patient of mine,” says Minkin. “She was 46 and came to me complaining about perimenopausal weight gain. I took one look at her and told her she was well into her second trimester.”
If you’re used to dealing with nausea, vomiting, bloat, and other upset-stomach issues, you may blow off morning sickness and an expanding belly as just more G.I. tract irritation says, Minkin. “And then when it disappears after a few months, you think it’s over—you wouldn’t realize you just passed your first trimester,” she says.