One in 600 women have no clue they're pregnant -- until delivery day. (Yes, really)

By Kaitlin Stanford for TheBump.com

We've all caught wind of some crazy delivery stories at some point or another. You know how they go: Waters spontaneously breaking at work, babies being delivered in the backseats of cabs…that sort of thing. But then there are those other crazy birth stories -- the ones that come as a complete and total shock to everyone -- including the mom-to-be. You know, the I-didn't-know-I-was-pregnant-until-suddenly-there-was-a-baby-in-my-pants-type stories. Yep. Laugh all you want (hey, we just did), but according to a recent study, it's more common than you think.

We can probably bet what you're asking yourself right now: How could anyone coast through nine months of pregnancy without experiencing at least a few obvious symptoms? What about the morning sickness, the crazy mood swings, the embarrassing gas, and -- do we even need to mention -- that ever-growing bump beneath your shirt? According to researchers in Germany and Ireland (and supported by our own research, like watching one too many episodes of TLC's I Didn't Know I Was Pregnant), "surprise" deliveries don't just happen to the totally clueless and naïve.

So who do they happen to? Looks like for the one in 600 women who make it through months of pregnancy apparently unaware or unaffected by their symptoms, it may be part luck, part denial. In truth, there are lucky women out there who don't really feel much morning sickness anyway or at least have such a mild case it's easily dismissed as a stomach bug or passing nausea. (And of these women, we're equal parts bitter and jealous.) Other pregnancy symptoms -- like gas, diarrhea, and breakouts --could also be blamed on passing sickness, diet changes, or the biggest catch-all: stress. But even so, one of the biggest pregnancy red flags -- loss of a period -- doesn't always sound the alarm for some women, especially if they have a history of irregular periods.

And as for that little thing called denial: Sue Macdonald of the Royal College of Midwives told Times Online recently, "An unplanned pregnancy can cause extreme anxiety, and anxiety produces a closed mind, which refuses to recognize symptoms..." Which is why -- for some women -- everything from nausea to belly kicks can be blamed on a whole laundry list of other things.

Read crazy labor and delivery stories here.

Still find it all pretty hard to believe? Crazy or not, surprise deliveries do happen. We asked moms on TheBump.com to weigh in on some of the wackiest stories they've heard. Here's what some had to say:

"I have a friend who went to the hospital thinking with what she thought was appendicitis, but it turned out she was in active labor. She was married, not overweight, and not stupid by any means. She even still had her 'period' every month on the dot, and only gained about 10 pounds, which she just attributed to not working out because she was so tired. I saw her a week before she had the baby, and she honestly didn't look pregnant." --grapeape73

"When I was 16, I knew a girl this happened to. She was my age and a tiny thing. Well, I saw her one day and not again for six weeks -- when she came in with a baby! I asked her who it was for, and was very surprised to hear it was hers. She said she'd never had a regular period, so she wasn't concerned when she missed a few months. She definitely didn't look pregnant, and had only gained a few pounds. She told me she went to the bathroom one day with what she thought was a terrible stomachache and DELIVERED THE BABY IN HER BATHROOM ALONE." --bourk997

"I knew a mom this happened to. She had a 2-and-a-half-year-old and a 10-month-old and was exclusively breastfeeding, so she didn't think anything of not having her period. She also didn't lose any of her baby weight so she wasn't really showing. She said she had terrible cramps one day and went to the OB and he told her there was nothing he could do -- she was something like six centimeters dilated. Talk about a surprise!" --chelseymat

Do you know any "surprise" delivery stories? How long were you pregnant for before you found out? Share here

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