Third trimester · 7 weeks to go
| Fact | Week 33 |
|---|---|
| Days of pregnancy | 225–231 since LMP |
| Gestational age span | 32w0d to 32w6d |
| Trimester | Third trimester (weeks 28–40) |
| Pregnancy month | Month 3 (weeks 9–13) |
| Average length | 17.2 in (crown to heel) |
| Average weight | 4.23 lb |
| Size comparison | a pineapple |
| Weeks remaining | 7 (40-week due date) |
Week 33 keeps the skull deliberately soft: the plates stay flexible and the sutures between them loose so the head can mold through the birth canal. Every other bone is hardening.
Amniotic fluid volume is at its peak and will slowly decline from here. The baby's immune system is developing its first antibody responses. The brain's skull plates flexibility is the body's smartest engineering for birth.
Gestationally, week 33 means you are 32 weeks and 0 to 6 days pregnant, day 225 to day 231 counted from the first day of your last period. This is week 6 of the third trimester (weeks 28–40). Appointments step up to every two weeks from week 28. Week 36 brings weekly appointments and lightening. From here the baby gains roughly half a pound a week on average, which is why the third trimester feels measurably heavier by the day. 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 33.
Slow down on stairs and put away the heels. Pack the hospital bag now if you haven't; early arrivals happen.
Weeks of pregnancy don't map cleanly to calendar months, but the common division puts week 33 falls in month 3 of pregnancy (weeks 9–13). Week 33 is part of the third trimester, which runs from week 28 to birth. Gestationally, week 33 means you are 32 weeks and 0 to 6 days pregnant.
At week 33 the baby averages 17.2 in long and weighs about 4.23 lb, roughly the size of a pineapple. 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.