You are officially halfway through your pregnancy. The fetus now has all its organs, muscles, and limbs in place. From here on, the focus is on growth, weight gain, and maturation. The anatomy scan, if not done yet, typically happens this week. Use our Due Date Calculator to track your timeline.
Key Takeaways
- At 20 weeks, your baby measures about 25 cm head to toe (the size of a banana) and weighs roughly 300 grams
- You are halfway — the baby will grow from 300 grams now to an average of 3,400 grams by 40 weeks
- The uterus has reached the navel; your provider will now measure fundal height at every visit
- Sleep-wake cycles are becoming more defined — you may notice the baby is most active at certain times
- The anatomy scan checks all major organs, the spine, the placenta, and can usually confirm the sex
Your Baby This Week
Size: Banana (about 16.5 cm crown to rump, or 25 cm head to toe)
Weight: About 300 grams
Starting this week, the fetus is measured from head to toe instead of crown to rump, because the legs are now extended rather than curled up.
- Swallowing practice: The fetus swallows several ounces of amniotic fluid daily, training the digestive system
- Meconium: Building up in the intestines. This dark, tarry substance will be the baby's first bowel movement after birth.
- Sleep-wake cycles: Becoming more defined. You may notice the baby is most active at certain times of day.
- Skin layers: The dermis, epidermis, and subcutaneous layer are all present
- Immune system: The spleen is producing white blood cells
- Taste preferences: Studies show that the baby swallows more amniotic fluid when it tastes sweet and less when it tastes bitter
Track your baby's growth with our Milestone Tracker.
Your Body
- Fundal height. Your uterus has reached your navel. From now on, your provider will measure the fundal height (the distance from pubic bone to the top of the uterus) at each visit. At 20 weeks, it should be about 20 cm.
- Belly button changes. Your innie may start to pop out as the uterus pushes from behind. This is normal and temporary.
- Shortness of breath as the uterus pushes upward against the diaphragm
- Leg cramps continue, especially at night
- Strong kicks and rolls that may be visible from the outside
What to Do This Week
- Attend your anatomy scan if scheduled. Bring your partner or a support person. This is often an emotional appointment, as you get a detailed look at your baby's face, hands, heart, and spine.
- Start researching childbirth classes. Whether you prefer hospital-based education, Lamaze, hypnobirthing, or online courses, now is a good time to sign up.
- Celebrate the halfway point. Some families have a gender reveal, a babymoon trip, or simply a special dinner. You have earned it.
- Start planning for delivery. You are halfway there, so it is a good time to begin thinking ahead. Our Hospital Bag Checklist will help you prepare when the time comes.
Common Questions
What if the anatomy scan finds something?
Most anatomy scans come back perfectly normal. If the sonographer flags something, try to stay calm. Some findings are minor variations that resolve on their own. Others may require additional testing or monitoring. Your provider will explain what was found and the recommended next steps.
How big will my baby get from here?
At 20 weeks, the baby weighs about 300 grams. By 40 weeks, the average newborn weighs about 3,400 grams (7.5 pounds). That means most of the weight gain happens in the second half of pregnancy, especially in the third trimester.
FAQ
What happens at the 20-week anatomy scan?
The anatomy scan (also called the morphology or structural scan) is a detailed ultrasound that checks the baby's brain, face, spine, heart, lungs, stomach, kidneys, bladder, limbs, and placenta position. It also assesses amniotic fluid levels. This is the most comprehensive prenatal ultrasound, and it can usually reveal the sex if you want to know.
Is the 20-week scan mandatory?
It is not legally mandatory, but it is strongly recommended by all major health organizations including the WHO, NHS, and ACOG. The scan can detect structural abnormalities that may require further monitoring, specialist care, or in some cases intervention. Missing it means missing an important diagnostic opportunity.
What if the anatomy scan finds something at 20 weeks?
Most anatomy scans are entirely normal. If the sonographer notes a finding, it may be a minor variation that resolves on its own, or it may warrant additional testing such as a follow-up scan or referral to a specialist. Try to stay calm and ask your provider to explain exactly what was seen and what the next steps are before drawing conclusions.
Is it normal for the belly button to pop out at 20 weeks?
Yes. As the uterus expands, it pushes against the abdominal wall, which can cause an innie belly button to flatten or protrude outward. This is called an umbilical hernia or simply "belly button popping" and is completely harmless. It typically reverts after birth.
How big should the uterus be at 20 weeks?
At 20 weeks, the uterus has reached the level of the navel. Your provider will measure fundal height — the distance from the pubic bone to the top of the uterus — at each prenatal visit from now on. At 20 weeks, fundal height should be approximately 20 cm, and it typically matches the number of weeks within 1 to 2 cm.
Related Articles
- Pregnancy Week-by-Week Overview — see the full timeline
- Fetal Development Trimester Guide — your baby's development
- Hospital Bag Checklist, start planning ahead
Sources
- ACOG - Ultrasound Exams
- NHS - Week 20 of Pregnancy
- Mayo Clinic - Fetal Development
- WHO - Pregnancy Care
🔧 Helpful Tools
- Due Date Calculator — Calculate your estimated due date
- Contraction Timer — Track your contractions during labor
- All Baby Tools — Browse all free tools for pregnancy and baby care
