The placenta grows with the baby, but not as fast. At this point in development, it weighs around 30g; at the time of birth, it will weigh between 450-900g or as much as a cabbage!
Over the course of the 13th week, the vocal cords will form in your baby’s larynx (voice box). The baby will not be able to make sounds, however, or cry out loud, because sound travels through air, not fluid.
Towards the end of this week, all of your baby’s 20 baby teeth and their sockets will have formed in the gums. Also during this week, the intestines will form into folds and become lined with villi (small, fingerlike projections in the lining of the intestines that absorb certain nutrients).
Just as in the past two months, you will continue to feel more tired than usual. Continue to listen to your body and make adjustments in your schedule so you can rest when you need to.
You may continue to need to urinate frequently. Again, that’s because your system is working more efficiently to remove waste and to circulate nutrients. It’s important to empty your bladder when it feels full. If this is a second pregnancy, your muscles may be less resistant to your growing uterus. Consequently, there’s less pressure right now on your bladder and more baby showing - so you may be wearing maternity clothes already.