Week 16: Your pregnancy

Your baby's growth: Facial expressions

Overall growth continues, and your baby now weighs about 2.8 to 3 ounces and is about 4 or 5 inches long.

You're not the only one who's smiling! Your baby can now make facial expressions because of the development of her facial muscles. This week she can squint, smile and frown. This is probably not an indication of mood but may be linked to random impulses in the developing brain.

Other highlights this week include:

• Head control. Her ability to make some voluntary muscle movements means she can now hold her head somewhat erect.
• Light sensitivity. She is developing sensitivity to light and may respond with heart rate accelerations to projections of light on the abdomen. Later in pregnancy, this can serve as a test of well-being before birth.
• Hiccups. They may start now, but you won't hear or feel them because the baby's system is filled with fluid rather than air.
• Heart. Her heart is now pumping the equivalent of 25 quarts of blood each day.
• Increased coordination. Arm and leg movements are becoming more coordinated.
• Bladder. Your baby's bladder will empty about every 40 to 45 minutes.

What's happening with you

• Need for more rest. As your pregnancy progresses it's important for you to get plenty of rest.

• New sleep position. The best position for you now is lying comfortably on your side, perhaps with a pillow propped against your back and another between your legs. The best sleeping position, specifically during the last couple of months of pregnancy, is on your left side. By lying on your left side you'll experience better digestive functioning; improved blood and nutrient flow to the placenta, and less swelling of hands, feet and legs.

  When lying on your left side, you're reducing pressure on the vena cava, a large vein that transports blood from the lower part of your body to your heart. Additionally, this position allows for both you and your baby to receive more oxygen.

  Avoid lying on your back because your uterus could block important blood vessels in the back of your abdomen and interfere with circulation to you and your baby. Also avoid lying on your stomach, which puts too much pressure on your growing uterus.

• Aches. If you move suddenly you may feel an ache in your sides. Not to worry. What you're feeling are the ligaments on the sides of your uterus and pelvic walls stretching as your baby grows. It's normal to feel some discomfort, but if it continues for a few days or if your discomfort increases, you may want to talk with your doctor.