Your Baby’s Development at 20 Weeks
At 20 weeks, baby is almost 6 3/4 inches (17 centimeters) from the top of the head to the bottom of the buttocks (known as the crown-rump length), and the baby’s height is approximately 9 1/2 inches (24.3 centimeters) from the top of the head to the heel (crown-heel length). This week, a baby weighs a little more than 11 1/2 ounces (330 grams). Which Trimester? Second trimester How Many Weeks to Go? 20 weeks
Reproductive System
By week 20, baby’s reproductive system has developed significantly.
Female: The development of human egg cells begins long before birth. The number of eggs in the ovaries is at its peak around 20 weeks, with about six to seven million eggs. This number decreases from this point on and continues to go down throughout life. Male: The testes are still in the abdomen, preparing to move to the inguinal area (groin) to begin their descent. However, the testes typically do not descend into the scrotum until the third trimester.
Other Developments
The protective layer of vernix continues to build on the skin.Hair follicles are getting longer.Eccrine sweat glands begin to form.The gallbladder is producing bile, which helps to digest nutrients.
Explore a few of your baby’s week 20 milestones in this interactive experience.
Your Common Symptoms This Week
The typical second-trimester symptoms such as heartburn, nasal congestion, and food cravings may continue this week. You may also be gaining weight, noticing changes in your belly button, or dealing with painful leg cramps.
Weight Gain
By week 20, you may have put on around 10 pounds. The general pregnancy weight gain guidelines suggest that after a gain of 1 to 5 pounds in the first trimester, you can expect to add approximately 1 pound a week for the rest of your pregnancy. Weight gain is not merely due to consuming more calories. Rather, it’s a combination of a lot of different things, including the weight of your growing baby, your uterus, the amniotic fluid, the placenta, and even your increased blood volume and breast tissue. Of course, everyone is different. Some people lose weight during the first trimester, and sometimes it’s put on faster than expected. You should talk to your doctor if you have any questions or concerns about your weight.
Belly Button Changes
As your uterus grows and expands up into your abdomen, it puts pressure on your abdominal wall. This pressure can change the appearance of your belly button. It doesn’t happen to everyone, but an innie belly button can become flattened or even an outie. While you can’t do anything to prevent this pop-out, know that this change is generally temporary and harmless.
Leg Cramps
Up to 45% of pregnant people experience leg cramps. These cramps most commonly occur in the calf muscles. They are painful, sudden, and usually happen at night.
Self-Care Tips
Continue to eat nutritious meals, get enough fluids, participate in safe physical activities, and take your prenatal vitamins. This week, you may also want to find ways to relieve leg cramps, and if you haven’t already, begin sleeping on your side.
Avoid Lying on Your Back
After 20 weeks, you should no longer lie down flat on your back. Your uterus and baby are growing big enough to put pressure on your abdominal organs, spine, and the major blood vessels in your body. This pressure can affect your circulation, slow down the flow of blood to your heart, and lower your blood pressure. To prevent low blood pressure from lying on your back (known as supine hypotension), you can: —Allison Hill, MD, OB/GYN
Sleep on your side with pillows or a wedge to help you from rolling onto your back. Don’t exercise lying flat on your back; use modifications instead. If you visit the dentist, go for a prenatal massage, or need a medical test, tell the staff you’re pregnant and avoid lying flat.
Dealing With Leg Cramps
Leg cramps are painful, and they can affect your sleep. Doctors aren’t sure what causes them, but it may involve inactivity or a deficiency in certain vitamins or minerals. To deal with leg cramps, you can:
Get a little daily exercise. Gently stretch the calf muscles. Practice relaxation techniques. Use massage or heat. Talk to your doctor about trying supplements such as calcium, magnesium, or vitamin B. Flex your foot forward (point your toes toward your head) during a cramp.
Advice for Partners
Your plans for preparing the house or a nursery for the new baby might include cleaning and painting. If so, this work is something you can do to lower your partner’s exposure to strong cleaning products and paint fumes. While there are no studies that link household paint to negative pregnancy outcomes, it’s widely recommended that pregnant people limit exposure to household paints and their fumes. Paint fumes, paint remover, and some cleaning products can be dangerous for your partner and your growing baby. To be on the safe side, follow these guidelines:
Read paint labels carefully and follow safety instructions.Don’t use outdoor paint for indoor rooms.Have your partner avoid fumes by not spending time in freshly painted rooms.Open windows and use a fan to air out rooms with fumes.Try to use low-VOC or zero-VOC paint. (Note that water-based paint tends to give off fewer vapors (VOCs) than oil-based paint.)Check the ingredients in cleaning products.Don’t mix cleaning products.Use cleaning solutions in well-ventilated areas.
At Your Doctor’s Office
You may have a scheduled prenatal visit this week. Like appointments before, your physician or midwife will:
Record your weight Take your blood pressure Ask you for a urine sample Talk to you about your symptoms Examine your body for swelling Answer your questions
Belly and Baby Growth
Your provider may feel for the top of your uterus around the level of your belly button, and they may also measure the distance from your pubic bone to the top of your uterus. This measurement is called the fundal height, and it can help estimate the size of the uterus and the baby’s growth. Fundal height is measured in centimeters. The measurement often matches the number of weeks pregnant (within a centimeter or two). So, at 20 weeks, your fundal height will likely be around 20 centimeters.
Ultrasound
Your 20-week visit may also include a structural ultrasound (also known as the anatomy scan or level 2 ultrasound). The technician will squirt a thin layer of cold jelly on your abdomen and use a hand-held transducer to look at your baby-to-be. This in-depth ultrasound looks at the development of your baby’s body parts and organs, the umbilical cord, the placenta, and the amniotic fluid. If you’d like, and your baby is cooperating, you can also learn the baby’s sex with this scan.
Special Considerations
As your belly expands and your belly button begins to flatten out or become an “outie,” you may have some concerns. It’s usually a normal change and not an issue. But, for some expecting parents, an outie might be more than it seems. A screening test for gestational diabetes is typical between 24 weeks and 28 weeks.
Umbilical Hernia
It’s normal for the belly button to pop out during pregnancy. However, in about 0.08% or 1 in 1,250 pregnancies, a popped out belly button can be due to a hernia. An umbilical hernia is a bulge in the belly button from fat tissue or the intestines poking through a hole or weak spot in the abdominal wall. During pregnancy, the pressure in the abdomen from the growing uterus can push the hernia out. An umbilical hernia can be small and without symptoms or large and painful. Treatment depends on the situation and symptoms. In most cases, treatment can wait until after the baby is born. However, surgery to repair the hernia may be recommended in some cases. If you notice a soft bulge around your belly button, your outie getting bigger, or belly button pain, be sure to talk to your doctor.
A Word From Verywell
Your pregnancy is halfway over. Over the last 20 weeks, your baby went from the tiny combination of an egg and a sperm the size of a pinpoint to a little human measuring 9 1/2 inches in length. Over the next 20 or so weeks, your baby is going to continue to grow bigger and stronger. You’ll be feeling more and more movement, and it won’t be long before your partner and others can feel your baby, too.
