Second trimester · 19 weeks to go
| Fact | Week 21 |
|---|---|
| Days of pregnancy | 141–147 since LMP |
| Gestational age span | 20w0d to 20w6d |
| Trimester | Second trimester (weeks 14–27) |
| Pregnancy month | Month 2 (weeks 5–8) |
| Average length | 10.5 in (crown to heel) |
| Average weight | 12.7 oz |
| Size comparison | a carrot |
| Weeks remaining | 19 (40-week due date) |
Week 21 brings rapid eye movements and the start of real sleep architecture. The baby's lips and eyebrows are more distinct, and drifting kicks are getting strong enough that a hand on the belly can feel them.
The digestive system is practicing for the first feeding, and the baby responds to sound with movement. Weight gain from here is mostly fat and muscle. The placenta keeps growing to match demand.
Gestationally, week 21 means you are 20 weeks and 0 to 6 days pregnant, day 141 to day 147 counted from the first day of your last period. This is week 8 of the second trimester (weeks 14–27). Prenatal appointments run about every four weeks in this stretch. Week 24 brings viability and the opening of the glucose-test window (weeks 24–28). Across this trimester the baby more than triples in weight, so expect your bump, your appetite, and eventually your waddle to keep pace with the calendar. Every number on this page is an average across pregnancies; your own scan dates and your baby's measurements are what actually describe your week 21.
Varicose veins improve with compression socks and walks. Irregular, painless tightenings are normal; call for painful, regular contractions.
Weeks of pregnancy don't map cleanly to calendar months, but the common division puts week 21 falls in month 2 of pregnancy (weeks 5–8). Week 21 is part of the second trimester, which runs from week 14 to week 27. Gestationally, week 21 means you are 20 weeks and 0 to 6 days pregnant.
At week 21 the baby averages 10.5 in long and weighs about 12.7 oz, roughly the size of a carrot. Sizes come from fetal growth charts (crown-to-heel length from week 20), and normal variation week to week is wide; your ultrasound measurements always outrank a chart.