As if the ability to produce another human being wasn't mind-blowing enough, pregnancy brings with it a host of other truly incredible changes that are almost impossible to believe until they happen to you. Here are five fascinating pregnancy facts that prove (as if we ever doubted it) that women have serious super powers: 1. Your body grows a brand new organ during pregnancy: Yep, as well as secreting hormones and providing oxygen, the placenta makes sure that the nutrition in your bloodstream gets passed to your baby. It can also grow up to nine inches wide and weigh up to three pounds. So, it's a pretty big deal. 2. Being pregnant makes you more flexible: And not just because of that mum-to-be yoga class. The placenta releases a hormone called relaxin while pregnant, which causes the cervix to dilate, the ligaments to relax and prepares the uterus for labour. 3. Your uterus expands to 500 times its usual size: The average size of a uterus is about that of a pear. During pregnancy however, it expands to about the size of a grapefruit at 12 weeks and a small watermelon - up to 500 times its normal size - in the ninth month of pregnancy. 4. You'll produce a truly impressive amount of oestrogen: A full-term pregnant woman produces more oestrogen in just one day than a woman who is not expecting produces in three entire years. Oestrogen is responsible for increasing the size or the number of tissues, vessels, and blood cells during all that growing. 5. Your heart gets bigger. Oh, and so do your feet: When they say motherhood changes you from head to toe, they aren't kidding. The cardiovascular system needs to accommodate an increase in blood volume as your baby grows, so the heart expands in size by around 12 per cent. As the ligaments in your feet relax, your foot size could increases by half a size. Sometimes this is permanent. Hey, it's an excuse to go shoe shopping, right? Have you discovered any other wacky pregnancy facts we should know about? Tell us on Twitter @HerFamilydotie.