Your baby is now about 5 ½ inches long and weighs about 6 ounces.  During this week the baby will gain weight at an incredible pace!  Now that all of the organs have developed the baby’s body will focus on gaining weight and size.  You may begin to feel a bit off center as the baby and your uterus is getting larger.

Because the baby’s inner ear has formed its bones and nerve endings from the brain have formed, hearing has become very acute.  Your baby can hear your heartbeat and the blood moving through the umbilical cord as well as your voice.  They will even try to cover their ears if they hear a loud sound! 

Baby becomes sensitive to light now, as the eyes are further developed and the brain is growing very fast.  A little girl will have all the eggs inside her ovaries that she will need for her entire life.  Little boys begin to develop the prostate gland.  Meconium, or the first bowel movement continues to accumulate inside the bowel.  Brown fat begins to cover the baby, so their skin appears less transparent.

This is the last week you would normally have an amniocentesis, if your health practitioner has suggested this test.  Often between 18-22 weeks your health practitioner will order an ultrasound.  You may begin to experience heartburn now, as the uterus begins to push upward on your stomach.  Try to eat several small meals and stay away from high fat items.  If you prop yourself up with pillows it can help with heartburn, too. 

Related Weeks
Fetal Development – Week 17 | Fetal Development – Week 19

Fetal Development Week by Week – Week 18