Free family guide · Pregnancy week by week · Third trimester

34 weeks pregnant

Week 34 is in the third trimester in both the US Office on Women's Health (OWH) system and the UK's NHS week-by-week guide.[1][2]

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Sources on this page: OWH; NHS; CDC; ACOG; MedlinePlus; NICHD; 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 baby is around 45 cm long.[3]
  • The NHS says the baby is curled up, and in boys the testicles are descending.[3]
  • CDC's Yellow Book says most airlines allow flying until 36 weeks, and some limit international flights earlier.[4]

Which trimester is week 34?

OWH counts the trimesters as weeks 1 to 12, 13 to 28 and 29 to 40.[1] The NHS guide counts them as weeks 4 to 12, 13 to 27 and 28 to 41.[2] 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.[5]

All three place week 34 in the third trimester.[1][2][5]

Your body this week

The NHS says the baby dropping lower, called lightening or engagement, can ease breathlessness and heartburn, but it does not mean birth is about to happen.[3] It says sleeping on your side helps blood flow to the placenta.[3]

Your baby this week

The NHS says the baby is around 45 cm long.[3]

The NHS says the baby is curled up, and in boys the testicles are descending.[3] It says swelling of a newborn's genitals goes down within days.[3]

Visits and tests around week 34

The NHS says there is an antenatal appointment at 34 weeks.[3]

Sources differ

Sources give different weeks for the group B strep test:[6][7][8]

  • OWH lists the group B strep test at weeks 36 to 37.[6]
  • ACOG says the swab is done at 36 to 38 weeks.[7]
  • MedlinePlus says the swab is done a few weeks before the due date.[8]

NICHD describes visits every 2 weeks from 28 to 36 weeks.[9]

Things to do this week

  • CDC's Yellow Book says most airlines allow flying until 36 weeks, and some limit international flights earlier.[4]
  • The NHS says the safest position to go to sleep is on your side, left or right.[10]
  • CDC says to avoid lying flat on your back during exercise after the first trimester.[11]
  • The NHS suggests packing your hospital bag at least 3 weeks before your due date.[12]

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.[13]

HRSA says the National Maternal Mental Health Hotline, 1-833-852-6262, takes calls and texts 24/7 in English and Spanish.[14]

When to call your provider or get help

MedlinePlus says to call your provider in the third trimester for:[8]

  • bleeding, or discharge that smells bad;[8]
  • fever, chills, or pain when you urinate;[8]
  • headaches or changes in vision;[8]
  • the water breaking, or regular painful contractions;[8]
  • the baby moving less;[8]
  • a lot of swelling, chest pain or trouble breathing.[8]

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.[15]

Questions families ask

Which trimester is week 34?

OWH places week 34 in the third trimester.[1] The NHS guide places it in the third trimester.[2] ACOG places it in the third trimester.[5]

How big is the baby at 34 weeks?

The NHS says the baby is around 45 cm long.[3]

What is lightening?

The NHS says it is the baby dropping lower, and it does not mean birth is about to happen.[3] MedlinePlus lists lightening among the signs that labor is near.[16]

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. Office on Women's Health (HHS). Stages of pregnancy. Checked October 24, 2026.
  2. NHS (United Kingdom). Week-by-week guide to pregnancy. Checked October 24, 2026.
  3. NHS (United Kingdom). 34 weeks pregnant guide. Checked October 24, 2026.
  4. Centers for Disease Control and Prevention (CDC Yellow Book). Pregnant Travelers. Checked October 24, 2026.
  5. American College of Obstetricians and Gynecologists. How Your Fetus Grows During Pregnancy. Checked October 24, 2026.
  6. Office on Women's Health (HHS). Prenatal care and tests. Checked October 24, 2026.
  7. American College of Obstetricians and Gynecologists. Group B Strep and Pregnancy. Checked October 24, 2026.
  8. MedlinePlus (National Library of Medicine). Prenatal care in your third trimester. Checked October 24, 2026.
  9. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH). What happens during prenatal visits?. Checked October 24, 2026.
  10. NHS (United Kingdom). Tiredness and sleep problems in pregnancy. Checked October 24, 2026.
  11. Centers for Disease Control and Prevention. Pregnant & Postpartum Activity: An Overview. Checked October 24, 2026.
  12. NHS (United Kingdom). Hospital bag checklist – what to pack for you and your baby. Checked October 24, 2026.
  13. National Institute of Mental Health (NIH). Perinatal Depression. Checked October 24, 2026.
  14. Health Resources and Services Administration (HRSA). National Maternal Mental Health Hotline. Checked October 24, 2026.
  15. NHS (United Kingdom). 32 weeks pregnant guide. Checked October 24, 2026.
  16. MedlinePlus (National Library of Medicine). Am I in labor?. Checked October 24, 2026.