Buzz·Posted on 9 Oct 201422 Utterly Bizarre Scientific Facts About PregnancyHow does a year-long pregnancy work for you?by Robyn WilderBuzzFeed Staff, UKLinkFacebookPinterestTwitterMail 1. Nipple stimulation is the only scientifically proven method of legitimately bringing on labour. 2. The longest known pregnancy lasted for a year and 10 days. 3. Babies can taste the food their mothers eat in the womb. View this vine on Vine vine.co Strong flavours like garlic can pass through the amniotic fluid in the womb, and a study showed that babies whose mothers drank a lot of carrot juice displayed a preference for carrot juice themselves. 4. There are more twins born in Central Africa than in anywhere else in the developing world. 5. And some people think it may have something to do with yams. View this vine on Vine vine.co But there's no real evidence to prove this. 6. It's possible to fall pregnant through oral sex. In fact, one woman conceived after oral sex and a knife fight. 7. From the second trimester onwards, babies pee in the uterus. Then they drink it. Then they pee again. Then they drink it. You get the picture. 8. In fact, amniotic fluid is mostly sterile urine. 9. A baby starts making its first poo, called meconium, at around 21 weeks' gestation. However, it won’t pass it until after its birth. 10. Pregnant woman and new mothers can lactate automatically when they hear a baby crying (even if it’s not their own). View this vine on Vine vine.co 11. Baby girls are born with all the eggs they will ever use, but boys don't develop sperm until puberty. 12. Rabbits, dogs, pigs, whales, and humans all start as eggs roughly the same size (around 0.2mm). 13. The old wives’ tale is true: Pregnant women who suffer with heartburn ARE more likely to give birth to babies with full heads of hair. View this vine on Vine vine.co / Via fitpregnancy.com Scientists suggest that the higher levels of oestrogen and progesterone that stimulate hair growth also relax the oesophagus, causing acid reflux. 14. For every 2,000 babies, one is born with a tooth. 15. Having a baby boy can increase the mother's risk of autoimmune diseases, and make her whatsitcalled worse. Forgetfulness, that's the word. View this vine on Vine vine.co / Via news.discovery.com Thanks, the patriarchy. 16. Babies cry in the womb. 17. A woman's uterus expands to more than 500 times its normal size over the course of a pregnancy. 18. When a pregnant woman is full term, her placenta will produce more oestrogen in a day than a non-pregnant woman would produce in three years. View this vine on Vine vine.co 19. In addition to her uterus, a woman's feet and heart increase in size during pregnancy. 20. A baby's fingerprints are set within the first three months of pregnancy. 21. Orgasms can cause contractions. 22. And this is how a baby's face forms in the womb. Tap to play GIF Tap to play GIF