Free family guide · Pregnancy week by week · Second trimester

28 weeks pregnant

Week 28 is in the second trimester in the US Office on Women's Health (OWH) system and in the third trimester in the UK's NHS week-by-week guide.[1][2]

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Sources on this page: OWH; NHS; ACOG; MedlinePlus; USPSTF; 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 baby is around 37.6 cm long from head to heel.[3]
  • The NHS says the baby's heart now beats about 140 times a minute, compared with about 110 when first detectable at week 5 or 6 and about 130 at birth.[3]
  • The NHS advises washing your hands for at least 20 seconds, especially after changing diapers.[3]

Which trimester is week 28?

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.[4]

Sources differ

Sources place week 28 differently:[1][2][4]

  • OWH places week 28 in the second trimester.[1]
  • The NHS guide places week 28 in the third trimester.[2]
  • ACOG places week 28 in the third trimester.[4]

Your body this week

The NHS says back strain, heartburn and swelling are common, and to get swelling checked for preeclampsia.[3] For a nosebleed, it suggests sitting up, leaning forward and pinching the nose for 10 to 15 minutes.[3]

Sources differ

Sources differ on extra calories in the third trimester:[3][5]

  • The NHS says to eat an extra 200 calories a day from week 28.[3]
  • MedlinePlus says most people need about 450 extra calories a day in the third trimester, and often none in the final weeks.[5]

Your baby this week

The NHS says the baby is around 37.6 cm long from head to heel.[3]

The NHS says the baby's heart now beats about 140 times a minute, compared with about 110 when first detectable at week 5 or 6 and about 130 at birth.[3] It says your own heart beats about 80 to 85 times a minute.[3]

Visits and tests around week 28

MedlinePlus says people who are Rh-negative have an antibody screen, and may be given a medicine around week 28.[6]

Sources differ

Sources give different weeks for the gestational diabetes test:[7][8][9][10]

  • The US Preventive Services Task Force advises screening at 24 weeks or later.[7]
  • NICHD says screening usually happens between 24 and 28 weeks.[8]
  • ACOG says glucose screening is usually done between 24 and 28 weeks, with blood drawn an hour after a sugar drink.[9]
  • OWH lists glucose challenge and tolerance tests at weeks 26 to 28.[10]

OWH lists a nonstress test after week 28, when a provider orders one.[10]

NICHD describes visits every 2 weeks from 28 to 36 weeks.[8]

Things to do this week

  • The NHS advises washing your hands for at least 20 seconds, especially after changing diapers.[3]
  • The NHS suggests wearing gloves for cat litter and gardening.[3]
  • The NHS suggests planning where the baby will sleep.[3]
  • CDC says to avoid lying flat on your back during exercise after the first trimester.[11]

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.[12]

HRSA says the National Maternal Mental Health Hotline, 1-833-852-6262, takes calls and texts 24/7 in English and Spanish.[13]

When to call your provider or get help

MedlinePlus says gestational high blood pressure and preeclampsia start after 20 weeks, and high blood pressure is often found only at checkups.[14]

CDC lists urgent warning signs to watch for during pregnancy and in the year after birth, including:[15]

  • a headache that will not go away or gets worse;[15]
  • changes in vision;[15]
  • extreme swelling of the hands or face;[15]
  • severe belly pain that does not go away;[15]
  • the baby's movement stopping or slowing;[15]
  • vaginal bleeding or leaking fluid;[15]
  • thoughts of harming yourself or the baby.[15]

Questions families ask

Which trimester is week 28?

OWH places week 28 in the second trimester.[1] The NHS guide places it in the third trimester.[2] ACOG places it in the third trimester.[4]

How big is the baby at 28 weeks?

The NHS says the baby is around 37.6 cm long from head to heel.[3]

How fast does the baby's heart beat at 28 weeks?

The NHS says about 140 times a minute.[3]

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). 28 weeks pregnant guide. Checked October 24, 2026.
  4. American College of Obstetricians and Gynecologists. How Your Fetus Grows During Pregnancy. Checked October 24, 2026.
  5. MedlinePlus (National Library of Medicine). Pregnancy and Nutrition. Checked October 24, 2026.
  6. MedlinePlus (National Library of Medicine). Prenatal care in your second trimester. Checked October 24, 2026.
  7. US Preventive Services Task Force. Gestational Diabetes: Screening. Checked October 24, 2026.
  8. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH). What happens during prenatal visits?. Checked October 24, 2026.
  9. American College of Obstetricians and Gynecologists. Routine Tests During Pregnancy. Checked October 24, 2026.
  10. Office on Women's Health (HHS). Prenatal care and tests. Checked October 24, 2026.
  11. Centers for Disease Control and Prevention. Pregnant & Postpartum Activity: An Overview. Checked October 24, 2026.
  12. National Institute of Mental Health (NIH). Perinatal Depression. Checked October 24, 2026.
  13. Health Resources and Services Administration (HRSA). National Maternal Mental Health Hotline. Checked October 24, 2026.
  14. MedlinePlus (National Library of Medicine). High Blood Pressure in Pregnancy. Checked October 24, 2026.
  15. Centers for Disease Control and Prevention (HEAR HER campaign). Urgent Maternal Warning Signs and Symptoms. Checked October 24, 2026.