Halfway
Twenty weeks. Half your pregnancy is behind you. The part where everything was invisible, uncertain, and hypothetical has given way to a belly you can't hide, a baby you can feel kicking, and an ultrasound appointment that's probably been circled on your calendar for weeks.
The anatomy scan is the appointment. It's the one your partner takes off work for. The one your mother asks about. The one that, depending on your choice, might answer the question "boy or girl?" But the anatomy scan is much more than a gender reveal. It's a methodical, head-to-toe evaluation of your baby's structural development, and it provides the most detailed picture of your baby's health that you'll receive during pregnancy [1].
Let's talk about what happens, what it means, and what to do with the feelings it stirs up.
Your Baby at Twenty Weeks
Your fetus is now about the size of a banana, measuring roughly 6.5 inches (16.5 cm) from crown to rump (about 10 inches head to heel) and weighing approximately 10 ounces [2]. From this point forward, measurements will typically be reported as head-to-heel rather than crown-to-rump, because the legs are now long enough to factor in meaningfully.
Development milestones at week 20:
- Vernix caseosa has formed, a waxy white coating that protects the skin from constant exposure to amniotic fluid. Some of this vernix will still be present at birth [6].
- The fetus swallows amniotic fluid regularly, which helps develop the digestive system. The waste material that accumulates in the intestines (called meconium) will become the baby's first bowel movement after birth [2].
- Sleep-wake cycles are beginning to emerge. Your baby alternates between periods of activity and rest, and you may notice that their movement patterns follow a rough schedule.
- Taste buds are functional. The flavors of what you eat reach the amniotic fluid, and your baby's taste preferences may already be forming [6].
- The uterus has reached the level of the navel. Your fundal height (the distance from the pubic bone to the top of the uterus) is approximately 20 centimeters, roughly matching your gestational age in weeks for the rest of the pregnancy [2].
The Anatomy Scan: What Really Happens
ACOG recommends that all pregnant women be offered a second-trimester ultrasound for fetal structural evaluation, ideally between 18 and 22 weeks of gestation [5]. At MomDoc, the anatomy scan is scheduled within this window and is one of the longest appointments you'll have.
Here's what the sonographer evaluates, system by system [1][3][4]:
Brain and Head: The cerebral hemispheres, ventricles, cerebellum, and cisterna magna are measured and assessed for normal structure. The face is checked for the presence of both eye orbits, the nasal bone, and an intact upper lip.
Spine: The entire spinal column is visualized from cervical to sacral segments, checking for proper alignment and the absence of defects.
Heart: The four-chamber view of the heart is assessed, along with the outflow tracts (aorta and pulmonary artery). The fetal heart is one of the most carefully evaluated structures because congenital heart defects are among the most common birth defects [4].
Abdomen: The stomach, kidneys, bladder, and abdominal wall are visualized. The insertion point of the umbilical cord is checked. The kidneys are evaluated for size and the presence of normal fluid in the renal pelvis.
Limbs: Arms, legs, hands, and feet are checked for the presence of all long bones and their appropriate length.
Placenta and Fluid: The placenta's location, size, and proximity to the cervix are assessed. Amniotic fluid volume is measured (too much or too little can signal potential issues). Cervical length may also be measured, particularly if there's a history of preterm birth.
The scan typically takes 30 to 45 minutes. Sometimes the sonographer needs you to shift positions because the baby isn't cooperating (curled up, facing the wrong way, or stubbornly covering the relevant body part with a hand). A full bladder may be requested for the beginning of the scan to improve image quality, though you'll likely be allowed to empty it partway through [4].
Anatomy Scan Anxiety
Let's address the elephant in the ultrasound room. The anatomy scan is exciting, but it can also be terrifying. The stakes feel higher than any previous appointment because the scan is specifically looking for problems. And the waiting room anxiety, sitting there knowing that in the next 45 minutes you'll learn whether your baby's heart, brain, and spine developed correctly, can be genuinely overwhelming.
Here's what helps: most anatomy scans are normal. The vast majority of women walk out of that room with reassuring results and a printout photo of a healthy baby's profile [4]. But the fear of "what if" is real, and pretending otherwise doesn't serve you.
If the sonographer goes quiet during a portion of the scan, it doesn't necessarily mean something is wrong. They're concentrating. They need specific angles and measurements, and some views require patience. If something does appear abnormal or unclear, you'll be told. Your provider may recommend a follow-up scan, a referral to maternal-fetal medicine, or additional testing, depending on the finding.
And then there's the sex question. "Should we find out?" is one of the most debated decisions of pregnancy. Some couples want to know for planning, bonding, or sheer impatience. Others love the surprise. Neither choice is better. Just tell your sonographer your preference at the start of the appointment so they don't accidentally reveal it on screen.
If you do find out the sex, a note: ultrasound-based sex determination at 20 weeks is highly accurate, but it's not infallible. Occasionally, the angle is tricky, or the baby's position makes a definitive call difficult. Your sonographer will tell you their confidence level.
Your Body at Twenty Weeks
- The bump is undeniable. At 20 weeks, most women have a clearly visible pregnant belly. The top of the uterus has reached the navel, and your body has adjusted its posture, gait, and center of gravity to accommodate it.
- Fetal movement is becoming regular. By now, most women are feeling daily movement. The kicks, rolls, and jabs may still be subtle for some, but they're becoming more consistent.
- Stretch marks may appear. As the skin on your abdomen, breasts, and hips stretches, pink or reddish lines called striae may develop. Genetics play a bigger role than any cream in determining whether you'll get them, but staying hydrated and moisturized helps with comfort.
- Leg cramps and swelling. Increased weight, blood volume, and uterine pressure on veins can cause leg cramps (especially at night) and mild swelling in the feet and ankles. Elevating your legs, staying active, and drinking plenty of water can ease both.
- Heartburn arriving. Progesterone relaxes the valve between the stomach and esophagus, allowing stomach acid to splash upward. Small, frequent meals and avoiding lying down immediately after eating are the first-line defense.
What MomDoc Wants You to Know
The anatomy scan is a milestone, not a verdict. For the overwhelming majority of families, it's a beautiful confirmation that development is on track. For the small percentage who receive findings that need further evaluation, MomDoc is equipped to provide clear explanations, compassionate counseling, and referrals to specialists if needed.
Come to the appointment with whatever feelings you're carrying. Excitement, dread, curiosity, or a tangled combination of all three. Your sonographer has seen every emotional response in that dimly lit room, and none of them are wrong.
You're at the halfway mark. The banana-sized baby on that screen has taste buds, sleep cycles, and a face detailed enough to see on ultrasound. In twenty more weeks, give or take, you'll see that face for real.