Week 20
Your baby is the size of a banana
Halfway. Twenty weeks down, twenty to go. Per Mayo Clinic, your baby is now banana-sized: about 6 1/3 inches from crown to rump and around 11 ounces. The anatomy scan likely happens this week if it hasn't already, and your provider starts measuring your belly with a tape from now on. Here's what's actually new at the midpoint, and what to do with it.
Key takeaways
- You're at the literal midpoint. Twenty weeks down, twenty to go. Take a beat to acknowledge that.
- Fundal height starts being measured this week. From now until about week 36, the centimeters from pubic bone to the top of your uterus should match your week count, give or take 2.
- The anatomy scan is usually done between 18 and 22 weeks. If yours isn't booked, book it this week.
- Childbirth education classes are usually taken between weeks 24 and 32. Slots fill fast. Research and register before week 24.
Why your baby's measurements change this week
Up until now, your baby's been measured from crown to rump (head plus body, with the legs curled up tight). From around week 20, many providers shift to head-to-toe measurements because the legs straighten and become easier to assess. Per Mayo Clinic, your baby is currently about 6 1/3 inches from crown to rump (160 mm) and weighs roughly 11 ounces. Head-to-toe, banana-length.
Big shift.
Underneath the vernix, a protein called keratin is building up in the developing skin, the same protein in your hair and nails. Skin is still thin and translucent. The fat layers that fill out classic newborn cheeks accumulate slowly over the next several weeks.
Sleep-wake cycles are established. Ultrasounds at this stage often catch your baby mid-stretch or mid-yawn. The four chambers of the heart, spine, kidneys, and limb proportions are all measurable now, which is why ACOG schedules the anatomy scan in this window.
Low-frequency sounds can begin reaching your baby's inner ear through bone conduction. Reliable, consistent responses to external sound show up later in pregnancy. Talk to the bump if you want to. Just don't expect a kick on cue.
Why your provider pulls out a tape measure this week
Welcome to the halfway point.
You've earned this one.
The top of your uterus (the fundus) is now at about your belly button. Starting around week 20, your provider measures fundal height (the distance from pubic bone to top of uterus) at every prenatal visit. Per Cleveland Clinic, the centimeters should match your weeks of pregnancy, plus or minus 2. Today, roughly 18 to 22 cm.
If you haven't felt regular movement yet, it's likely imminent. Movements vary day to day at 20 weeks, and formal kick counting doesn't start until about 28 weeks per ACOG.
Second-trimester symptoms settle in around now: leg cramps at night, mild ankle swelling, occasional shortness of breath, and increased clear or whitish vaginal discharge. Back pain may join in as your center of gravity shifts.
Emotionally, the halfway point can feel surreal. The pregnancy stops being a thing you're 'in' and starts being a countdown. Many parents notice a shift in how they think about names, the nursery, hospital bags, the actual labor experience.
One concrete thing to do this week: research childbirth education classes. Per Mayo Clinic, most are taken between weeks 24 and 32, and good slots fill fast. Register before week 24.
Contact your provider right away if you have heavy bleeding, severe one-sided pain, fluid leakage, fever above 100.4°F, or a sudden, sustained drop in movement after you've been feeling it regularly.
For dads
Here's your move:
The anatomy scan, if you haven't done it yet, is happening this week or next. Block 45 to 60 minutes. Sometimes it runs longer. Before you go, talk through at home whether you want to know the sex and how: in the room, sealed in an envelope, or saved for a separate reveal. Decide together so the sonographer isn't standing by while you whisper. While you're at it, take 30 minutes this week to research one big-ticket item: car seat, stroller, or crib. Bring two real options to your next registry conversation. That kind of focused prep takes more weight off your partner than any flowers will.
Real talk:
The midpoint is a good time for an honest check-in with yourself. How are you actually feeling about becoming a dad? Excited? Nervous? Some private mixture you don't want to name out loud? All of it is normal, and most of it gets worse if you bottle it. Talk to your partner. Talk to a friend who's been through it. The cultural script that men should just absorb the change quietly doesn't serve you, your partner, or your kid. The next twenty weeks go faster than you think. They also bring real change. Show up for yourself the same way you're trying to show up for her, and the partnership you're building now will hold up under what comes after.
Common concerns
Is 20 weeks really halfway?+
Mathematically yes. Twenty weeks down, roughly twenty to go. Many parents find weeks 20 to 30 fly by while the final stretch crawls, and only about 5% of babies arrive on the exact due date. The normal range is 37 to 42 weeks.
What if the anatomy scan finds something abnormal?+
Most flagged findings turn out to be soft markers that resolve, measurement variations that normalize, or positioning issues needing a follow-up scan. If your provider finds a concern, they'll explain it, recommend further testing, and walk you through the options.
How often should I feel my baby move at 20 weeks?+
Movement is still becoming established, so you shouldn't expect a regular pattern yet. Per ACOG, formal kick counting (10 movements within 2 hours) starts around 28 weeks, not now.
When should I sign up for childbirth classes?+
Research now and register soon. Most classes are designed to be taken between weeks 24 and 32 per Mayo Clinic, and popular options fill quickly.
Product picks for week 20
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Pearhead Hello Baby Photo Album
Gender-neutral keepsake album sized for sonogram prints and the early baby photos that begin with this week's anatomy scan.
FITRELL Compression Socks (3 Pairs, 20-30 mmHg)
Graduated compression for the mild ankle swelling that often shows up around now as blood volume continues climbing.
Momcozy U-Shaped Pregnancy Pillow (57 inch)
Full-body U-shape supporting back, belly, and hips when leg cramps at night and a shifting center of gravity make sleep harder.
Sources
- Mayo Clinic, Fetal Development: The 2nd Trimester (2025) — https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20046151
- ACOG, Ultrasound Exams (2024) — https://www.acog.org/womens-health/faqs/ultrasound-exams
- Cleveland Clinic, Fundal Height: Measurement, What It Means & Accuracy (2024) — https://my.clevelandclinic.org/health/diagnostics/22294-fundal-height
- ACOG, Indications for Outpatient Antenatal Fetal Surveillance (2021) — https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2021/06/indications-for-outpatient-antenatal-fetal-surveillance
- Mayo Clinic Perinatal Education, Frequently Asked Questions (2024) — https://perinataleducation.mayoclinic.org/faqs/
A quick note: This content is for informational purposes only and is not a substitute for professional medical advice. Always talk to your healthcare provider about any questions or concerns. Content based on guidance from the American College of Obstetricians and Gynecologists (ACOG), the American Academy of Pediatrics (AAP), Mayo Clinic, and peer-reviewed medical literature. Learn how we create our content.