At 20 weeks, you’re at the halfway point of pregnancy. Your baby is about 6⅓ inches long from crown to rump and weighs roughly 11 ounces, or about the size of a banana. This is the week most people have their anatomy scan, a detailed ultrasound that checks your baby’s organs and growth. It’s also when many of the physical changes of pregnancy become harder to ignore: your belly is visibly growing, you may be feeling your baby move for the first time, and your body is adapting in ways that can be both exciting and uncomfortable.
Your Baby’s Size and Development
At 160 millimeters crown to rump, your baby has grown dramatically from the tiny embryo of the first trimester. All major organs are formed and continuing to mature. The ears are developed enough that your baby can hear your voice and other sounds. Taste buds, which started forming around week 9, are now functional. Your baby is swallowing amniotic fluid regularly, which helps the digestive system practice for life outside the womb.
The skin is still thin and translucent, covered in a fine layer of hair called lanugo that helps regulate temperature. A waxy, white coating called vernix is building up to protect the skin from the amniotic fluid. Beneath the surface, fat stores are just beginning to develop, and the nervous system is rapidly wiring new connections.
Feeling Your Baby Move
Somewhere between 16 and 24 weeks, most people feel their baby move for the first time. If this is your first pregnancy, you might not notice movement until after 20 weeks. Those early sensations typically feel like a gentle swirling or fluttering, sometimes described as bubbles or a light tapping. It’s easy to mistake them for gas at first.
If you’ve been pregnant before, you’ll likely recognize the feeling sooner, sometimes as early as 16 weeks. As the weeks progress, those subtle flutters will become unmistakable kicks and jerky movements. At 20 weeks, the movements are still inconsistent. You won’t feel them at regular intervals yet, and that’s completely normal. Regular kick-counting patterns become more relevant later in the third trimester.
The Anatomy Scan
The 20-week ultrasound is the most thorough imaging you’ll have during pregnancy. A sonographer takes detailed pictures and measurements of your baby’s heart, brain, head, neck, spine, kidneys, bladder, arms, legs, hands, fingers, feet, toes, face, chest, lungs, stomach, and intestines. They’ll record the heart rate and measure the length of your baby’s limbs, head, and belly.
This scan is designed to catch structural issues early. The sonographer checks that the heart has four functioning chambers, that the brain is developing normally, that the spine is closed, and that organs like the kidneys and stomach are in the right place and the right size. The appointment usually takes 30 to 45 minutes, longer if your baby is in an awkward position. Many people also learn the sex of their baby at this scan, though you can choose not to.
If anything looks unusual, you may be referred for a follow-up scan or additional testing. Sometimes the sonographer simply can’t get a clear view of a particular structure and needs you to come back.
How Your Body Is Changing
By 20 weeks, the top of your uterus (the fundus) has reached your belly button. From this point forward, your healthcare provider will measure your fundal height at each visit. The measurement in centimeters should roughly match the number of weeks you are, plus or minus two. So at 20 weeks, a measurement between 18 and 22 centimeters is typical.
Weight gain varies, but for someone who started pregnancy at a normal BMI (18.5 to 24.9), the expected rate during the second and third trimesters is about one pound per week. Factoring in a small gain during the first trimester, most people in this category have gained somewhere around 8 to 12 pounds by the halfway mark. This number shifts based on your starting weight, whether you’re carrying multiples, and individual factors your provider tracks over time.
Round Ligament Pain
One of the most common complaints at 20 weeks is a sharp, stabbing pain on one or both sides of the lower belly. This is round ligament pain. The round ligaments support your uterus, and as it expands, these ligaments stretch longer and wider. They normally contract and loosen slowly, so a sudden movement like rolling over in bed, standing up quickly, or even sneezing can make them spasm.
A few things help. Move slowly when changing positions. If you feel a sneeze or cough coming, lean forward and hold your belly to brace the ligaments. Gentle yoga or hip-flexing stretches throughout the day can reduce tension. One floor stretch that many people find effective: get on your hands and knees, lower your head toward the floor, and keep your hips up. Done daily, this can take pressure off the ligaments.
Sleep and Comfort
As your belly grows, finding a comfortable sleep position gets harder. You’ve probably heard you should sleep on your side, and side-sleeping does take pressure off the large blood vessels that run behind the uterus. But the evidence on back-sleeping is less alarming than many people fear. Experts at the University of Utah note there isn’t enough data to say that back-sleeping directly causes harm. The concern may be more closely linked to sleep apnea, which becomes more common as pregnancy progresses and airways narrow. Snoring and disrupted breathing during sleep can reduce oxygen delivery, and back-sleeping can make that worse.
A pillow between your knees and another supporting your belly can make side-sleeping more comfortable. If you wake up on your back, don’t panic. Simply roll to your side and go back to sleep.
Blood Pressure Screening
The 20-week mark is a meaningful dividing line for blood pressure monitoring. Any high blood pressure detected before 20 weeks is classified as chronic hypertension, meaning it likely existed before pregnancy. New high blood pressure that develops after 20 weeks is classified as gestational hypertension, or preeclampsia if accompanied by protein in the urine or signs of organ stress. The threshold is a systolic reading above 140 or a diastolic reading above 90.
Your blood pressure at 20 weeks also serves as a useful baseline. Research published in Circulation shows that readings at this stage help identify people at heightened risk for pregnancy-related hypertension later on, even if their early pregnancy numbers looked fine. This is one reason your provider checks your blood pressure at every visit and pays close attention to any upward trend.
Iron and Nutrition
Your blood volume is increasing significantly during the second trimester, and your body needs more iron to keep up. The recommended daily intake during pregnancy is 27 milligrams, nearly double the typical amount in a standard diet (about 15 milligrams). Many people develop low iron stores by midpregnancy without realizing it, since fatigue is so easy to attribute to pregnancy itself.
Your provider may check your iron levels around this time. Ferritin, the protein that stores iron, is the most useful marker. Levels below 30 micrograms per liter generally indicate iron deficiency during pregnancy. Iron-rich foods like red meat, spinach, lentils, and fortified cereals help, and your prenatal vitamin contributes as well. If your levels are low, your provider may recommend an additional iron supplement. Taking it with vitamin C (like a glass of orange juice) improves absorption, while calcium and coffee can block it.