Free family guide · Pregnancy week by week · First trimester

11 weeks pregnant

Week 11 is in the first 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; USPSTF; ACOG; MedlinePlus; NICHD; FoodSafety.gov; NIMH; HRSA; CDC

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 41 mm long.[3]
  • The NHS says the fingers and toes are separating and tiny fingernails are growing.[3]
  • The US Preventive Services Task Force advises a daily folic acid supplement through the first 2 to 3 months of pregnancy.[4]

Which trimester is week 11?

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 11 in the first trimester.[1][2][5]

ACOG says pregnancy is counted from the first day of the last menstrual period, so 2 weeks are counted at the beginning when you are not yet pregnant.[5]

Your body this week

The NHS says your body is pumping up to 50% more blood, which can make you feel hot or dizzy.[3] It says to see your midwife if aches around your belly hurt a lot.[3]

Your baby this week

The NHS says the baby is around 41 mm long.[3]

The NHS says the fingers and toes are separating and tiny fingernails are growing.[3] It says the baby is kicking, but you will not feel it for some weeks.[3] It says the placenta is taking over from the yolk sac.[3]

Visits and tests around week 11

The NHS says blood, urine and blood pressure tests are offered around now.[3] It says the dating scan may include a nuchal translucency measurement as part of Down syndrome screening.[3]

OWH lists chorionic villus sampling (CVS) at weeks 10 to 13.[6] ACOG also says CVS is done between 10 and 13 weeks.[7]

Sources differ

Sources give different weeks for first-trimester screening:[6][8]

  • OWH lists the first trimester screen at weeks 11 to 14.[6]
  • ACOG says the blood test and nuchal translucency ultrasound are usually done together between 10 and 13 weeks.[8]

ACOG says cell-free DNA screening can be done from 10 weeks, with results in about 1 week.[8]

The NHS says its dating scan is done at 8 to 14 weeks.[9]

MedlinePlus says prenatal testing is optional and is your decision, made with your provider.[10]

For a healthy pregnancy, NICHD describes visits once a month until 28 weeks.[11]

Things to do this week

  • The US Preventive Services Task Force advises a daily folic acid supplement through the first 2 to 3 months of pregnancy.[4]
  • The NHS advises 400 micrograms of folic acid a day until at least week 12.[9]
  • MedlinePlus says to keep caffeine under 200 mg a day, about 1 to 2 small cups of coffee or tea.[12]
  • FoodSafety.gov says to avoid hot dogs and deli meats unless they are reheated until steaming (165°F).[13]

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.[14]

HRSA says the National Maternal Mental Health Hotline, 1-833-852-6262, takes calls and texts 24/7 in English and Spanish.[15]

When to call your provider or get help

CDC lists urgent warning signs to watch for during pregnancy and in the year after birth, including:[16]

  • a headache that will not go away or gets worse;[16]
  • dizziness or fainting;[16]
  • a fever of 100.4°F (38°C) or higher;[16]
  • severe nausea and vomiting;[16]
  • severe belly pain that does not go away;[16]
  • vaginal bleeding or leaking fluid;[16]
  • thoughts of harming yourself or the baby.[16]

MedlinePlus says some people spot in early pregnancy and do not miscarry, but any bleeding should prompt a call to a provider.[17]

Questions families ask

Which trimester is week 11?

OWH places week 11 in the first trimester.[1] The NHS guide places it in the first trimester.[2] ACOG places it in the first trimester.[5]

How big is the baby at 11 weeks?

The NHS says the baby is around 41 mm long.[3]

What is the nuchal translucency scan?

ACOG says first-trimester screening is a blood test plus an ultrasound measurement called nuchal translucency, usually done together between 10 and 13 weeks.[8] MedlinePlus says prenatal testing is optional.[10]

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). 11 weeks pregnant guide. Checked October 24, 2026.
  4. US Preventive Services Task Force. Folic Acid Supplementation to Prevent Neural Tube Defects: Preventive Medication. 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. Prenatal Genetic Diagnostic Tests. Checked October 24, 2026.
  8. American College of Obstetricians and Gynecologists. Prenatal Genetic Screening Tests. Checked October 24, 2026.
  9. NHS (United Kingdom). 4 weeks pregnant guide. Checked October 24, 2026.
  10. MedlinePlus (National Library of Medicine). Prenatal Testing. Checked October 24, 2026.
  11. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH). What happens during prenatal visits?. Checked October 24, 2026.
  12. MedlinePlus (National Library of Medicine). Caffeine in the diet. Checked October 24, 2026.
  13. FoodSafety.gov (HHS, USDA, FDA). People at Risk: Pregnant Women. Checked October 24, 2026.
  14. National Institute of Mental Health (NIH). Perinatal Depression. Checked October 24, 2026.
  15. Health Resources and Services Administration (HRSA). National Maternal Mental Health Hotline. Checked October 24, 2026.
  16. Centers for Disease Control and Prevention (HEAR HER campaign). Urgent Maternal Warning Signs and Symptoms. Checked October 24, 2026.
  17. MedlinePlus (National Library of Medicine). Miscarriage. Checked October 24, 2026.

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