Day 152 of 280 · 21 weeks + 5 days
Awake and asleep
Last reviewed · 3 min read · 7 sources · Plain-text version
Twenty-one weeks and five days. Your baby is settling into times of waking and sleeping. For a week, you note their busiest hour, and get some rest yourself.
- Size this week
- about the size of a carrot
- Length this week
- around 26.7 cm from head to toe

Twenty-one weeks and five days. Your baby is starting to keep hours of their own. Neither of you is on a schedule yet, but you can start to notice theirs.
Your baby

Around now your baby is around 26.7cm long from head to toe, about the size of a carrot (NHS). They're moving around a lot and establishing waking and sleeping patterns (NHS). By 24 weeks, the NICHD says, the fetus sleeps and wakes on a regular schedule (NICHD). Some of the quiet stretches you notice may simply be sleep.
Your body
You may be tired, and sleeping badly at night. The NHS suggests naps to make up for it (NHS), and MedlinePlus agrees that short daytime naps can make up lost sleep (MedlinePlus).
For the nights: lying on your side with your knees bent is likely the most comfortable position, and a pillow between your legs or under your belly can ease the pressure (MedlinePlus). Many providers recommend the left side, and it's best not to sleep flat on your back (MedlinePlus). Cut back on caffeine, and avoid large meals or lots of fluids in the few hours before bed (MedlinePlus).
Try today
The pattern log
Time: 1 minute a day for a week
Each evening, write one line: the hour today when the baby was busiest, and roughly what you were doing (after a meal, lying down, at your desk).
Write down if you didn't notice much. That's information too.
At the end of the week, read the seven lines together and compare them with any notes you've made before.
Keep the page. There's no set number of movements that counts as normal; what matters later is a change from your baby's usual pattern (CDC).
Make it work:Movement is easier to notice when you're still. The NHS says babies may move more after meals and while you relax (NHS).
Watch for
Normal
feeling movement on some days and not others; a woman may begin to feel movement at 20 weeks (NICHD).
Seek care immediately
, once you know the pattern, if the baby's movement slows or stops (CDC).
Normal
lying awake at 3 a.m.
Call your provider
before taking any sleep aid, including over-the-counter medicines and herbal products (MedlinePlus).
Normal
heartburn that's worse at night (MedlinePlus).
Go to the ER
for vomit that is bloody or looks like coffee grounds, black or maroon stools, or burning chest pain with squeezing or pressure (MedlinePlus).
For you
A fair warning: the baby's busy times don't always suit yours. Later in pregnancy, the NHS says, their active periods may coincide with your bedtime (NHS). Bank the rest while you can. An afternoon nap isn't laziness; it's on the NHS's list.
If you're the partner: find out the busy hour from the log and be there for it. Sit beside her with a hand on the bump and wait. It may take a few evenings.
Sources
- NHS. "Week 21." Week-by-week guide to pregnancy, Best Start in Life. https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-21/
- Eunice Kennedy Shriver National Institute of Child Health and Human Development. "About Pregnancy." National Institutes of Health. https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo
- MedlinePlus. "Problems sleeping during pregnancy." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000559.htm
- Centers for Disease Control and Prevention. "Urgent Maternal Warning Signs and Symptoms." HEAR HER campaign, 2024. https://www.cdc.gov/hearher/maternal-warning-signs/index.html
- NHS. "Week 17." Week-by-week guide to pregnancy, Best Start in Life. https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-17/
- MedlinePlus. "Heartburn." Medical Encyclopedia, National Library of Medicine. https://medlineplus.gov/ency/article/003114.htm
- NHS. "Week 29." Week-by-week guide to pregnancy, Best Start in Life. https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-29/
This guide is general education that summarizes published research and guidance from groups like the American Academy of Pediatrics, the CDC, and the WHO. It isn’t medical advice, and every child develops on their own timeline. Your pediatrician knows your child; if something feels wrong, call them. In an emergency, call 911.
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