37 Weeks Pregnant: Baby Size, Symptoms and What to Do

Your baby this week

Your baby is practicing facial expressions like squinting and frowning. Babies born from 37 weeks on are no longer considered preterm.

From 37 weeks 0 days your baby is no longer considered preterm; ACOG calls 37+0 to 38+6 early term. Your baby is practicing breathing and sucking and making facial expressions. For you, losing your mucus plug, stronger practice contractions and more discharge can be signs your body is getting ready, though labor may still be days or weeks away. Call labor and delivery right away if your water breaks (especially if the fluid is green or brown), you have bright red bleeding, or your baby is moving less. Make sure your hospital bag, car seat and plan for getting to the hospital are ready.

By the numbers

Week 37 covers days 259 to 265 counted from the first day of your last period, which is 93% of a 40-week pregnancy. About 21 days remain until a 40-week due date. Since last week, an average baby gains about 7.8 oz (220 g). By date of conception, your baby is about 35 weeks old.

Pregnancy is dated from the first day of your last period, so conception happens around week 2. Your due date is 280 days (40 weeks) from that day, and an early ultrasound may adjust it.

Your body

You may lose your mucus plug, and practice contractions can get stronger. Call if your water breaks, you have bleeding, or contractions become regular.

Tests and to-dos this week

If your GBS test isn't done yet, it's due this week. Keep your bag by the door and your provider's number saved in your phone.

• Group B strep (GBS) test · weeks 36–37 · test

  A vaginal and rectal swab, between 36 0/7 and 37 6/7 weeks per ACOG.

• Weekly visits · weeks 36–40 · visit

Signs of labor: when to go in

Labor usually starts with contractions that come at regular intervals and get longer, stronger and closer together; they don't ease when you rest or change position. Your water may break with a gush or a slow trickle, and you may notice a bloody show. Agree with your provider on when to call: many practices use the 5-1-1 rule of thumb (contractions about every 5 minutes, lasting about 1 minute, for 1 hour). Go in right away for bleeding, green or brown fluid, a severe headache, constant pain or fewer movements. A contraction timer helps you track the pattern without doing the math.

Contraction timer

Tips for the third trimester

• From 28 weeks, go to sleep on your side; if you wake on your back, just roll over.
• Pack your hospital bag and agree with your provider on when to head in.
• Call right away, even at night, if your baby moves less or differently.
• Know the signs of labor: regular, strengthening contractions, your water breaking or a bloody show.

Last week and next week

Last week (36): The lungs are likely mature enough for your baby to breathe without help after birth.

Next week (38): Most of the lanugo is gone.

Frequently asked questions