It is hard to imagine not realising you are pregnant.
Whether it’s the morning sickness, missed periods, or the fact a HUMAN is literally growing inside you, you would think it is unmissable.
But according to some statistics, about one in 450 only finds out they are pregnant after 20 weeks, with one in 2,500 not connecting the dots until they are in labour.
For Caitlin Ritter, she was 21 when she fell pregnant and only realised at the seven-month mark.
Caitlin says she was behaving like any other normal uni student would, which is everything not recommended for pregnant women.
“I was going out most weekends and getting drunk with my friends, sleeping my way through class and having a few one-night stands,” Caitlin told the Daily Telegraph.
I was doing what every other uni student was doing.
Caitlin says she wasn't getting her period before pregnancy, so there weren't any changes to be noticed there. The only flags she could remember was being a bit more tired than usual, peeing more frequently, and experiencing some heartburn.
Her weight gain was limited to just a few kilos and the week before she found out she was pregnant, she was in a bikini on the beach with a flat stomach.
This was all at seven months.
The moment Caitlin put two and two together was when she was lying down and saw her belly moving.
"...when I looked down at my belly, I saw an external movement - an arm or a leg - push out into my belly like the scene from the movie Alien.
"That's when I realised I was pregnant, but it wasn't until I made the necessary appointments and I heard the baby's heartbeat that it really hit home."
Scroll through to see some of the most unexpected pregnancies on our screens. (Post continues after gallery.)