More on 17 weeks Preggers

Sometime between week 17 and week 20 of pregnancy, your baby's hearing develops. This means that he or she can hear sounds, both inside and outside of your body.

During this week your baby will start to produce "brown fat," which has been shown to help heat production and metabolism later in life. Other changes that are occurring in your baby around 17 weeks of pregnancy include the following:

• White fatty material, called myelin, begins to enclose the nerve fibers of the spinal cord.
• Lanugo (a soft, fine hair) covers your baby's shoulders, back, and temples.
• Your baby's lungs are beginning to "breathe" the amniotic fluid (although the placenta will still supply the necessary oxygen until he or she is born).
• The circulatory and urinary systems are working.
• The reflexes are quickly developing. These reflexes will allow your baby to swallow, suck, and blink.