Week 20: Your pregnancy
Your baby's growth: More brain growth
Your little one now weighs about 9 to 12 ounces and has grown to about 6 to 8 inches in length. She's come a long way since her first days as a microscopic collection of cells but has a lot more growing to do. The average newborn is 18 to 21 inches long and weighs 6 to 9 pounds at birth.
The 20th week is an important time for your baby's sensory development, as nerve cells serving each of the senses. Taste, smell, hearing, seeing and touch are now developing into their specialized area of the brain. As these existing nerve cells get bigger and make more complex connections with each other, the brain's production of additional nerve cells will slow.
Believe it or not you're halfway there on the journey toward holding your new baby! Other baby developments this week include:
- Skin. Under the protective vernix coating, her skin will continue to develop into three layers: the dermis, epidermis and subcutaneous layers.
- Nails and hair. Your baby's nails and hair will continue to grow.
- Heart. Your baby's heartbeat will be stronger now, and the heart will beat about twice as fast as yours. You can hear it this week through a stethoscope.
- Increased size. Your baby will take up more and more space in the uterus, and her continued growth will put more pressure on your lungs, stomach, bladder and kidneys.
What's happening with you
- Increased uterus growth. Your uterus has reached your navel. At 20 weeks your uterus is probably growing a bit less than 1/2 per week. If you're much bigger than normal your doctor may perform an ultrasound to see whether you're carrying twins or if your estimated due date is correct.
Stretched abdominal muscles. The enlarging uterus also will begin to stretch your abdominal muscles, and they may begin to pull apart as she grows. First-time moms may not notice such a separation, but with each pregnancy it becomes more visible.
These muscles are attached to the lower part of your ribs and stretch down to the pelvis. You can see the separation more clearly if you lie down and raise your head, tightening the abdominal muscles—you'll notice a bulge in the middle of your abdomen. It isn't harmful or painful, and although exercising can strengthen these muscles, the bulge will still occur. After you give birth these muscles will return to their original place, and the separation will become less noticeable.
- Skin itchiness. You may also notice your skin is getting itchy as the uterus grows. This is because as your uterus grows, it stretches your skin. Lotions may help soften skin and ease the itch.
- Belly button changes. Don't be surprised if your belly button has changed from an "innie" to an "outie" and starts to protrude. This change is a result of the pressure behind it. It will revert close to its pre-pregnancy shape after delivery.
Varicose veins. Most women who experience varicose veins are genetically predisposed to the condition. Varicose veins are simply blood vessels that are filled with pooled blood. They usually appear in the legs or vulva.
Wearing support hose, sleeping on your left side, and elevating your legs can help drain the veins. It's also a good idea to stay off your feet, wear flat shoes and avoid crossing your legs. Varicose veins usually become less noticeable after delivery.
- Shortness of breath. Some women have a bit of trouble catching their breath as their internal organs press against the lungs. This breathlessness will usually continue until the baby "drops," or moves into position in the pelvis. For first pregnancies, babies usually drop four to six weeks before birth. With subsequent pregnancies it occurs closer to when labor begins.