Your 9 months Pregnancy You're 31 weeks pregnant Find out how your baby is developing in your 31st week of pregnancy 1 of Ad break How big is your baby?Your baby is now around 28cm long from the top of his head to his bottom - that’s about the size of a pineapple.Now find out how your baby is growing… How is your baby growing?He now weighs around 1.5kg and because he’s putting on more baby fat, he’s looking less wrinkly and much plumper than before. Your baby’s getting more hair on his head. The languo, the fine hair that’s been covering his body, is starting to disappear. Your baby has daily patterns of sleep and wakefulness – you’ll probably be able to notice when he’s awake because he’ll be more active in your womb. The cerebral cortex has matured, so your baby can now feel and remember. Because he’s more aware, if he hears a noise, he might react to it, perhaps with a kick! Your baby’s skeleton continues to harden, and fingernails and toenails are also growing. Now find out what’s happening to your body… What’s happening to your body?Your body is producing a hormone called relaxin. This softens the ligaments in your pelvis, so your pelvic bones can move during labour. If your ligaments soften too much, your joints can become misaligned, and you might experience pelvic pain. This is a common pregnancy condition called symphysis pubis dysfunction, or SPD. The pain can feel worse when you walk, put weight on one leg or part you legs. If you’re experiencing pain like this, you should pay a visit to your GP or midwife. The treatment for SPD will depend on how severe it is, and you’ll need to talk to your midwife about what birthing positions will work best for you. Learn more about what symptoms to expect this week and check out our week by week pregnancy guide... Find out how your baby developed in week 30 if your pregnancy, and see what will happen when you’re 32 weeks pregnant. By Sara Mackenzie Comments Latest on MadeForMums Must-have toys for Christmas from the biggest sellers Why e-books might be better for your toddler than paper ones Toddler wets herself after being blocked from using toilet on plane Could these be Beyonce and Jay-Z's twin baby names?