39 Weeks Pregnant
third trimester · Month 9
1 Weeks to Go!
Baby is as long as a watermelon (small)
Key Takeaways
- Full term — baby ready for life outside
- Placenta still nourishing; antibody transfer peaks
- Brain and lungs fully mature
39 Weeks Pregnant
Baby’s Development
Your baby is now about 50.7 centimeters long, roughly the size of a small watermelon, and weighs around 3,300 grams (about 7.3 pounds) [1]. Your baby is now full term and ready for life outside the womb. The placenta is still doing its important work, and right now antibody transfer is at its peak — your body passes immunoglobulin G (IgG) across the placenta, giving your baby passive immunity that will help protect them for the first six months of life. Your baby’s brain and lungs are fully mature, and body fat now makes up about 15 percent of their weight, leaving the skin smooth and plump. Most babies are settled head-down (cephalic) by now. The survival rate at 39 weeks is over 99 percent [2].
Pregnancy Symptoms
You are in your third trimester and officially full term, which means your baby could safely arrive any day now. You may be feeling the familiar discomforts of late pregnancy: backache, heartburn, constipation, leg cramps, swelling, headaches, and Braxton Hicks contractions that are growing more intense. Your uterus measures about 39 centimeters in fundal height. Lightening is complete, and you may notice your baby’s kicks are distinct but come a little less often now that there’s less room to move. Round ligament pain, sciatica, and pelvic pressure tend to intensify at this stage. You’ll be having weekly OB visits from here on. Your cervix may be effacing and dilating 1 to 3 centimeters. Watch for the signs that labor has truly begun: a bloody show, your water breaking, or regular contractions [2].
Body Changes
Your uterus now measures about 39 centimeters in fundal height, and a total weight gain of 30 to 38 pounds by this point is typical. Your bump is large and has likely “dropped” as your baby settles lower into your pelvis. You may notice stretch marks, the linea nigra down your belly, melasma (the “pregnancy mask”), more visible veins, and varicose veins. Your breasts have likely grown two or more cup sizes, and some colostrum may be leaking as your body prepares to feed your baby. Swelling in your feet and ankles is common. Your cervix is likely effacing and may be dilating 1 to 3 centimeters [2].
Tips for Week 39
- Keep counting your baby’s kicks — aim for at least 10 movements within a 2-hour window each day. If you count fewer than 10, try eating a snack, drinking something cold, and lying on your left side before counting again. A second low count is a reason to call your provider.
- Ease your anxiety about labor — talk to your provider, attend a childbirth class, consider hiring a doula, read evidence-based birth stories, and spend some time visualizing the day going well.
- Finalize your postpartum plan — line up who will be helping, plan meals ahead, arrange dog care, confirm your work leave, and prepare any siblings for the new arrival.
- Relieve pelvic pressure — practice Kegels, sleep on your side, try a support belt, and consider prenatal physical therapy if the pressure is significant.
Things To Do (Checklist)
- Continue kick counting (10 in 2 hrs daily)
- Address labor anxiety
- Finalize postpartum plan
- Address pelvic pressure
- Confirm hospital bag ready, route mapped
- Fetal position; cervix check; discuss induction if no labor by 41 wk
Frequently Asked Questions
Q: When will labor start? A: For first-time mothers, the average is around 40 weeks and 5 days. About half of first-time moms deliver by 40 weeks and 5 days, and about three-quarters by 41 weeks and 2 days. If you’re feeling “overdue,” try not to worry — it’s very common [1].
Q: Should I have an induction? A: This is a conversation to have with your provider. ACOG notes that offering induction at 39 weeks is supported by the ARRIVE trial, which showed slightly better outcomes. Standard practice is to offer induction at 41 weeks, though some providers will offer it earlier. Talk through the options together [1].
Q: How long does labor last? A: For first-time mothers, labor typically lasts 12 to 24 hours in total — about 6 to 12 hours in early labor, 4 to 8 hours in active labor, and 1 to 3 hours of pushing. Subsequent labors tend to be shorter [2].
For Dads
- Become the “5-1-1” expert — when contractions are 5 minutes apart, lasting 1 minute each, for 1 full hour, it’s time to call your provider and head to the hospital. Time the contractions using an app like Full Term or Contraction Timer.
- Finalize the logistics — set the go-bag by the door, map the route, sort out parking, line up a backup driver, arrange child and pet care, and block off your work calendar.
- Practice your labor support skills — learn counter-pressure, breathing cues, position changes, and what to say (and what not to say) during the hard moments.
- Read The Expectant Father, Chapters 37–38 — these cover labor, your role, and the decisions you may face in the moment.
- Pray for a safe, healthy labor and delivery — for the moment of meeting your baby, and for the gift of new life.
Sources
- ACOG — How Your Fetus Grows During Pregnancy
- Mayo Clinic — 39 Weeks Pregnant
- What to Expect When You’re Expecting — Heidi Murkoff (Chapters 21-22: Labor Signs)
Sources
- guideline ACOG — How Your Fetus Grows During Pregnancy
- medical Mayo Clinic — 39 Weeks Pregnant
- book What to Expect When You're Expecting — Heidi Murkoff
Your Checklist
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Action Plan Items for Week 39
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