If you are pregnant and at 16 weeks, your baby is a little over 4 inches in length (crown-to-rump) and weighs about 2 – 3 ounces. Rapid and sustained growth will continue all through this week, as muscles grow stronger and your baby’s head and neck grow straighter. The body is finally starting to catch up with the head growth now.
Your baby’s eyes are sensitive to light and if a bright light is held against your belly, it may gradually move its hands up to shield its eyes, even though they are still firmly closed. Your little baby’s genitals are formed well enough now that it may be possible to tell the gender on ultrasound, although ultrasounds can be wrong when it comes to gender determination, especially done this early in pregnancy.
Your uterus will continue to move upwards which will start to relieve the pressure on your bladder, and as a result, your need for frequent urination should be reduced. The top of your uterus has risen up, so you can probably feel it easily about 3 inches below your belly button.
Sleeping on your belly has most likely become too uncomfortable, while sleeping on your back may cause your growing uterus to compress major blood vessels (the aorta and the inferior vena cava). You will need to learn to sleep on your side, using extra pillows for support.
Some women experience constipation during pregnancy and a change in bowel habits. Make sure that you drink lots and lots of water, as much as eight 8-ounce glasses a day and add extra fiber to your diet. Exercise also helps, so try going for a daily walk.