Free family guide · Pregnancy week by week · Third trimester

42 weeks pregnant

MedlinePlus says labor usually starts between 37 and 42 weeks.[1]

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Sources on this page: MedlinePlus; NHS; OWH; ACOG; NICHD; CDC; NIMH; HRSA

This page shares what health organizations say. It is not medical advice. It is general information. Talk to your doctor, midwife or pediatrician about your own situation.

In an emergency, call 911.

At a glance

  • The NHS says the average baby weighs around 3 to 4 kg at birth.[2]
  • The NHS says the safest position to go to sleep is on your side, left or right.[3]

Which trimester is week 42?

OWH counts the trimesters as weeks 1 to 12, 13 to 28 and 29 to 40.[4] The NHS guide counts them as weeks 4 to 12, 13 to 27 and 28 to 41.[5] ACOG counts the first trimester to 13 weeks 6 days, the second from 14 weeks to 27 weeks 6 days, and the third from 28 weeks to 40 weeks 6 days.[6]

Sources differ

Sources place week 42 differently:[4][5][6]

  • OWH's third trimester runs to week 40.[4]
  • The NHS week-by-week guide ends at week 41.[5]
  • ACOG's third trimester runs to 40 weeks 6 days.[6]

Your body this week

MedlinePlus says labor usually starts between 37 and 42 weeks.[1] It says induction may be used after the due date or if there is a problem.[1]

The NHS says that from 41 weeks the risks start to increase, though they are still very small, and it lists extra monitoring or induction as options.[2]

Your baby this week

The NHS says the average baby weighs around 3 to 4 kg at birth.[2]

Visits and tests around week 42

NICHD describes visits every week from 36 weeks until birth.[7]

Things to do this week

  • The NHS says the safest position to go to sleep is on your side, left or right.[3]
  • CDC says to avoid lying flat on your back during exercise after the first trimester.[8]

Feelings check-in

The National Institute of Mental Health (NIMH) says perinatal depression includes depression during pregnancy, and its signs last at least 2 weeks.[9]

HRSA says the National Maternal Mental Health Hotline, 1-833-852-6262, takes calls and texts 24/7 in English and Spanish.[10]

When to call your provider or get help

MedlinePlus says to call your provider in the third trimester for:[11]

  • bleeding, or discharge that smells bad;[11]
  • fever, chills, or pain when you urinate;[11]
  • headaches or changes in vision;[11]
  • the water breaking, or regular painful contractions;[11]
  • the baby moving less;[11]
  • a lot of swelling, chest pain or trouble breathing.[11]

The NHS says you should still feel the baby move at the same rate until you give birth, and to contact your midwife or hospital as soon as possible if the pattern changes or the baby stops moving.[12]

Questions families ask

Which trimester is week 42?

OWH's third trimester runs to week 40.[4]

Is labor still normal at 42 weeks?

MedlinePlus says labor usually starts between 37 and 42 weeks.[1] The NHS says that from 41 weeks the risks start to increase, though they are still very small.[2]

Free from UpOnly Learning. Written for families of every faith. No outside ads and no affiliate links. Every fact on this page comes from the sources listed below. How we source and review these pages

Updated 2026-10-24: first published.

Sources

All sources were opened and checked on the date shown.

  1. MedlinePlus (National Library of Medicine). Childbirth. Checked October 24, 2026.
  2. NHS (United Kingdom). 41 weeks pregnant guide. Checked October 24, 2026.
  3. NHS (United Kingdom). Tiredness and sleep problems in pregnancy. Checked October 24, 2026.
  4. Office on Women's Health (HHS). Stages of pregnancy. Checked October 24, 2026.
  5. NHS (United Kingdom). Week-by-week guide to pregnancy. Checked October 24, 2026.
  6. American College of Obstetricians and Gynecologists. How Your Fetus Grows During Pregnancy. Checked October 24, 2026.
  7. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH). What happens during prenatal visits?. Checked October 24, 2026.
  8. Centers for Disease Control and Prevention. Pregnant & Postpartum Activity: An Overview. Checked October 24, 2026.
  9. National Institute of Mental Health (NIH). Perinatal Depression. Checked October 24, 2026.
  10. Health Resources and Services Administration (HRSA). National Maternal Mental Health Hotline. Checked October 24, 2026.
  11. MedlinePlus (National Library of Medicine). Prenatal care in your third trimester. Checked October 24, 2026.
  12. NHS (United Kingdom). 32 weeks pregnant guide. Checked October 24, 2026.