How Big is the Baby at 15 Weeks Pregnant?Your baby is a about the size of an orange by pregnancy week 15, between 4 and 4 and ½ inches long and weighing more than 1 ½ ounces!
Your Baby's Growth and DevelopmentYour baby is growing rapidly as always as you continue your pregnancy week by week journey. You would still be able to see your baby's blood vessels through his paper-thin skin if you were to peek inside your uterus during pregnancy week 15. In fact the vessels forming in your baby's body make him look rather like a map! This week your baby will start producing lanugo, which is fine hair that will cover your baby's body up until a few weeks before birth. Lanugo covers every part of your baby in utero, except for the palms, soles of the feet, lips, penis, nails and inner fingers and toes. Typically babies will shed this hair by the 8th month of pregnancy, but it can persist in some after birth for a short period of time. Pre-term babies are more likely to be born with lanugo than full term babies. Your baby might start sucking his thumb this week.

The bones in your baby's body are also starting to get harder during pregnancy at 15 weeks and will continue to do so throughout your pregnancy. Your baby is spending most of his time practicing breathing, by inhaling and exhaling amniotic fluid. Believe it or not, the very act of doing so will help your baby's air sacs develop during pregnancy. Your baby continues to form taste buds at this point in time.