Week 20 of Pregnancy: Halfway There
Halfway. Week 20 is also anatomy scan week for many couples, the most detailed look anyone gets at your baby before the birth. Treat it as a medical examination rather than a photo session, clear the entire day rather than the appointment slot, and be in the room.
- Block the entire day of the anatomy scan, not just the appointment slot.
- Walk in knowing it is a detailed medical examination, not a photo session.
- If anything is flagged, write down the exact words and ask what happens next, when, and who to call.
- Do not promise her the outcome will be fine; promise her you are not going anywhere.
▸Halfway, and why the length suddenly jumps
At 20 weeks pregnant the baby is around the size of a handball and roughly 300 grams. If the length appears to have doubled overnight, it has not. The measurement convention changes around week 20, from crown-to-rump to head-to-heel. Same baby, longer tape measure.
The real changes are internal. The baby is swallowing amniotic fluid regularly and the digestive system is rehearsing, with meconium, the tar-like first bowel movement you will meet in the delivery room, starting to accumulate. Hair is appearing on the scalp. Sleep and wake cycles are becoming a pattern, and it will not match yours.
▸What the 20 week anatomy scan actually checks
The anatomy scan, also called the mid-pregnancy or 20-week scan and commonly done between about 18 and 22 weeks, is a systematic head-to-toe examination. The sonographer works through the structures of the brain and skull, the face and lips, the length of the spine, the chambers and outflow tracts of the heart, the stomach, kidneys and bladder, the abdominal wall, and the limbs, including measuring the long bones and checking hands and feet.
It is not only about the baby. They look at where the placenta has implanted, at the umbilical cord, and at how much amniotic fluid there is, and they take growth measurements to compare against the dates. If you are being told the sex, that is a short aside at the end of a long checklist, not the reason the appointment exists.
The NHS says the scan usually takes around 30 minutes, and it can run longer if the baby is lying awkwardly and they need her to move around or come back another day. Being asked back to finish the views is common and does not mean anything is wrong. The sonographer will often go quiet mid-scan; that is concentration, not bad news. What they see is interpreted by them and by a doctor, and the real picture comes from that reading, not from your read of their face.
▸If they find something
Most scans are reassuring. Some are not, and if you are reading this straight after a difficult appointment, none of it is a failure of anything either of you did. A scan can pick up a structural difference, a finding that prompts further testing, a placenta lying low, or growth that does not match the dates. Some are minor and resolve. Some lead to a specialist referral, repeat scans, or the offer of further diagnostic tests. Some are serious.
Your job in that hour is clerical, and it matters more than it sounds. Write down the exact words used, including the name of anything mentioned, spelled out. Ask three questions before you leave: what happens next, when, and who do we call in the meantime. Ask whether there is a specialist midwife or counsellor attached to the referral, because there frequently is and nobody volunteers it.
Then protect the next 48 hours. Do not search alone at 2am, and do not hand her the worst cases you found. Tell family only what you have both agreed to tell them. And do not promise her it will be fine. You do not know that, she knows you do not know that, and saying it quietly ends the conversation she may need to have. That you are here and will find out together is true, which is what makes it useful.
▸Your job on the day
Block the day, not the appointment slot. Scans run late, and there is no version of this where you go straight back into a meeting afterwards.
Check the clinic instructions in advance, because they vary: some ask her to arrive with a full bladder and some do not, and policies differ on who may attend and whether other children are allowed. Turn your phone off rather than to silent. Let the sonographer work without narrating, and hold your questions until the checks are done. If images are available, ask at the end.
Decide beforehand about the sex, including whether you want to be told at all, and say so clearly when you walk in. Then, whatever the appointment holds, mark the halfway point somewhere quiet afterwards. Twenty weeks is a genuine milestone, and you will not get this particular evening again.
▸What she is going through
- The anatomy scan happens around now, a huge milestone.
▸Your missions this week
Concrete things worth doing in week 20, not just being supportive.
▸Questions dads actually ask
What do they check at the 20 week scan?
The sonographer works systematically through the baby's brain and skull, face, spine, heart, stomach, kidneys, bladder, abdominal wall and limbs, and takes growth measurements. They also assess the placenta's position, the cord, and the amniotic fluid. It is a detailed medical examination interpreted by the sonographer and a doctor, not a photo appointment.
How long does the 20 week anatomy scan take?
Usually around 30 minutes according to the NHS, and it can run longer. If the baby is lying awkwardly they may ask her to walk around, empty her bladder, or return another day to finish the views, and being asked back for that reason is routine. Clear the whole day rather than just the slot, including time afterwards.
Should dads go to the 20 week scan?
Yes, if you can. It is the most detailed look at the baby anyone gets before the birth, and it is also the appointment where difficult news, if there is any, gets delivered. You are there to listen, write things down and ask what happens next. Check the clinic policy on who can attend beforehand.
Can they tell the sex at the 20 week scan?
Usually, if the baby is lying in a position that allows it and if you ask. It is not guaranteed and it is not what the appointment is for, and some clinics have a policy of not disclosing it at all. Decide as a couple beforehand whether you want to know, and tell the sonographer at the start either way.
▸Sources
Checked against these pages on 17 Oct 2026. Where the guidance differs by country, follow your own midwife or doctor.
- NHS: Week 20 of the week-by-week guide
- ACOG: How your fetus grows during pregnancy
- NHS: 20-week scan
- ACOG: Ultrasound exams
▸Leave deadlines coming up
UK: you must tell your employer the due date at least 15 weeks before the baby is due, which is around week 25. Get your UK paternity leave dates →
US: FMLA needs at least 30 days' notice when you can plan the leave. Check FMLA eligibility and your dates →
▸Situations you might be hitting right now
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This is general information for expectant fathers, not clinical guidance. Anything about symptoms, pain, or bleeding goes to your midwife, doctor, or emergency service, not to an app.
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