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

Your baby this week

The outer layer of skin has thickened. Your baby may still have some vernix at birth.

Week 39 starts full term by ACOG's definition (39+0 to 40+6). Your baby's outer layer of skin has thickened, and there may still be some vernix at birth. Labor could start any day. Early signs include contractions that become regular and stronger, your water breaking or a bloody show. The first stage of labor, especially with a first baby, can take many hours, and many people spend the early part at home if their provider agrees. Between contractions, eat something light, drink and rest. Some providers offer induction at 39 weeks; talk through the options so the decision fits you and your baby.

By the numbers

Week 39 covers days 273 to 279 counted from the first day of your last period, which is 98% of a 40-week pregnancy. About 7 days remain until a 40-week due date. Since last week, an average baby gains about 7.4 oz (210 g). By date of conception, your baby is about 37 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

Labor could start any day. Follow the plan you made with your provider: call when contractions are regular and getting stronger, or if your water breaks.

Tests and to-dos this week

Keep up your weekly visit. Rest when you can and keep your phone charged.

• 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 (38): Most of the lanugo is gone.

Next week (40): Your baby is full term and short on space, but should keep moving in the usual pattern.

Frequently asked questions