Free family guide · Pregnancy week by week

Second trimester: weeks, symptoms and tests

The Office on Women's Health (OWH) counts the second trimester as weeks 13 to 28.[1] The NHS guide counts it as weeks 13 to 27, and ACOG as 14 weeks 0 days to 27 weeks 6 days.[2][3]

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Sources on this page: OWH; NHS; ACOG; MedlinePlus; WHO; 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.

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Weeks in this trimester

Week 1313 weeks pregnantWeek 1414 weeks pregnantWeek 1515 weeks pregnantWeek 1616 weeks pregnantWeek 1717 weeks pregnantWeek 1818 weeks pregnantWeek 1919 weeks pregnantWeek 2020 weeks pregnantWeek 2121 weeks pregnantWeek 2222 weeks pregnantWeek 2323 weeks pregnantWeek 2424 weeks pregnantWeek 2525 weeks pregnantWeek 2626 weeks pregnantWeek 2727 weeks pregnantWeek 2828 weeks pregnant

Your body

OWH lists these changes in the second trimester:[1]

  • body aches;[1]
  • stretch marks;[1]
  • darker patches of skin, sometimes called the “mask of pregnancy”;[1]
  • tingling in the hands, called carpal tunnel.[1]

MedlinePlus also lists leg swelling and varicose veins among common symptoms of pregnancy.[4]

Your baby

  • OWH says the baby can hear and swallow by about week 20.[1]
  • OWH says the baby has fingerprints and taste buds by about week 24.[1]

Sources differ

Sources give different weeks for first feeling the baby move:[5][6]

  • The NHS page on symptoms to get help for says first movements are felt from around 16 to 24 weeks.[5]
  • The NHS week 17 page says many women first feel movement between 18 and 24 weeks.[6]

Tests in the second trimester

OWH lists these tests:[7]

  • amniocentesis at weeks 14 to 20;[7]
  • the maternal serum screen at weeks 15 to 20;[7]
  • a standard ultrasound, often at weeks 18 to 20;[7]
  • glucose challenge and tolerance tests at weeks 26 to 28.[7]

MedlinePlus adds:[8]

  • a quad screen between weeks 15 and 22, most accurate at weeks 16 to 18;[8]
  • an anatomy ultrasound around week 20;[8]
  • an antibody screen for people who are Rh-negative, with a medicine possibly given around week 28.[8]

Sources differ

Sources give different weeks for the mid-pregnancy ultrasound:[7][8][9][10]

  • OWH lists a standard ultrasound, often at weeks 18 to 20.[7]
  • MedlinePlus lists an anatomy ultrasound around week 20.[8]
  • ACOG says at least one standard ultrasound is usually done at 18 to 22 weeks.[9]
  • The NHS week 18 page says its anomaly scan is offered at around 18 to 20 weeks.[10]

The World Health Organization (WHO) recommends one ultrasound before 24 weeks.[11]

Sources differ

Sources give different timing for the gestational diabetes test:[12][13][14][15][7]

  • The US Preventive Services Task Force advises screening at 24 weeks or later.[12]
  • NICHD says screening usually happens between 24 and 28 weeks.[13]
  • CDC says testing is usually done at 24 to 28 weeks, and people at higher risk may be tested earlier.[14]
  • ACOG says glucose screening is usually between 24 and 28 weeks, or earlier with risk factors.[15]
  • OWH lists the glucose tests at weeks 26 to 28.[7]

The US Preventive Services Task Force advises blood pressure screening throughout pregnancy.[16]

Taking care of yourself

  • MedlinePlus says most people need about 340 extra calories a day in the second trimester.[17]
  • MedlinePlus lists 27 mg of iron and 600 mcg of folic acid a day during pregnancy.[17]
  • CDC says to avoid lying flat on your back during exercise after the first trimester.[18]
  • CDC suggests at least 150 minutes a week of moderate activity, unless there is a medical reason not to.[18]
  • CDC's Yellow Book says most cruise lines restrict travel after 24 weeks.[19]

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.[20]

HRSA says the National Maternal Mental Health Hotline, 1-833-852-6262, takes calls and texts 24/7 in English and Spanish.[21]

When to call or get help

MedlinePlus says gestational high blood pressure and preeclampsia start after 20 weeks.[22] It says high blood pressure is often found only at checkups.[22]

MedlinePlus lists these signs of preeclampsia:[22]

  • protein in the urine;[22]
  • swelling of the face and hands;[22]
  • a headache that does not go away;[22]
  • changes in vision;[22]
  • pain in the upper right belly;[22]
  • trouble breathing.[22]

CDC lists the baby's movement stopping or slowing among its urgent warning signs in pregnancy.[23]

Questions families ask

How many weeks is the second trimester?

OWH counts weeks 13 to 28.[1] The NHS guide counts weeks 13 to 27, and ACOG counts 14 weeks 0 days to 27 weeks 6 days.[2][3]

When is the anatomy ultrasound?

MedlinePlus says around week 20.[8] OWH lists a standard ultrasound, often at weeks 18 to 20.[7]

When is the glucose test?

The US Preventive Services Task Force advises screening at 24 weeks or later.[12] NICHD says it usually happens between 24 and 28 weeks.[13]

How many extra calories do I need in the second trimester?

MedlinePlus says about 340 extra calories a day.[17]

When will I feel the baby move?

The NHS says first movements are felt from around 16 to 24 weeks.[5] Its week 17 page says many women first feel movement between 18 and 24 weeks.[6]

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. American College of Obstetricians and Gynecologists. How Your Fetus Grows During Pregnancy. Checked October 24, 2026.
  4. MedlinePlus (National Library of Medicine). Common symptoms during pregnancy. Checked October 24, 2026.
  5. NHS (United Kingdom). Pregnancy symptoms you need to get help for. Checked October 24, 2026.
  6. NHS (United Kingdom). 17 weeks pregnant guide. Checked October 24, 2026.
  7. Office on Women's Health (HHS). Prenatal care and tests. Checked October 24, 2026.
  8. MedlinePlus (National Library of Medicine). Prenatal care in your second trimester. Checked October 24, 2026.
  9. American College of Obstetricians and Gynecologists. Ultrasound Exams. Checked October 24, 2026.
  10. NHS (United Kingdom). 18 weeks pregnant guide. Checked October 24, 2026.
  11. World Health Organization. New guidelines on antenatal care for a positive pregnancy experience (news release, Nov 7, 2016). Checked October 24, 2026.
  12. US Preventive Services Task Force. Gestational Diabetes: Screening. Checked October 24, 2026.
  13. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH). What happens during prenatal visits?. Checked October 24, 2026.
  14. Centers for Disease Control and Prevention. Gestational Diabetes. Checked October 24, 2026.
  15. American College of Obstetricians and Gynecologists. Routine Tests During Pregnancy. Checked October 24, 2026.
  16. US Preventive Services Task Force. Hypertensive Disorders of Pregnancy: Screening. Checked October 24, 2026.
  17. MedlinePlus (National Library of Medicine). Pregnancy and Nutrition. Checked October 24, 2026.
  18. Centers for Disease Control and Prevention. Pregnant & Postpartum Activity: An Overview. Checked October 24, 2026.
  19. Centers for Disease Control and Prevention (CDC Yellow Book). Pregnant Travelers. Checked October 24, 2026.
  20. National Institute of Mental Health (NIH). Perinatal Depression. Checked October 24, 2026.
  21. Health Resources and Services Administration (HRSA). National Maternal Mental Health Hotline. Checked October 24, 2026.
  22. MedlinePlus (National Library of Medicine). High Blood Pressure in Pregnancy. Checked October 24, 2026.
  23. Centers for Disease Control and Prevention (HEAR HER campaign). Urgent Maternal Warning Signs and Symptoms. Checked October 24, 2026.