Free family guide · Pregnancy week by week · First trimester

7 weeks pregnant

Week 7 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]

Last reviewed: Next review: No outside ads and no affiliate links.

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

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 10 mm long from head to bottom.[3]
  • The NHS says the forehead looks large because the brain is growing fast, with around 100 new brain cells every minute.[3]
  • The NHS says a dating scan at 8 to 14 weeks gives a more accurate due date.[3]

Which trimester is week 7?

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]

All three place week 7 in the first trimester.[1][2][4]

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.[4]

Your body this week

The NHS says your blood volume will rise by up to 50% over the pregnancy, and suggests drinking about 8 medium glasses of fluid a day.[3]

The NHS says to report unusual symptoms such as itching all over.[3]

Your baby this week

The NHS says the baby is around 10 mm long from head to bottom.[3]

The NHS says the forehead looks large because the brain is growing fast, with around 100 new brain cells every minute.[3] It says the limb buds are forming cartilage.[3]

Visits and tests around week 7

The NHS says its dating scan is done at 8 to 14 weeks.[5]

For a healthy pregnancy, NICHD describes visits once a month until 28 weeks.[6]

Things to do this week

  • The NHS says a dating scan at 8 to 14 weeks gives a more accurate due date.[3]
  • ACOG's Committee Opinion 700 says a first-trimester ultrasound is the most accurate way to set or confirm how far along a pregnancy is.[7]
  • CDC says to talk to your providers before you start or stop any medicine.[8]
  • The NHS advises 400 micrograms of folic acid a day until at least week 12.[5]

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

CDC lists urgent warning signs to watch for during pregnancy and in the year after birth, including:[11]

  • a headache that will not go away or gets worse;[11]
  • dizziness or fainting;[11]
  • a fever of 100.4°F (38°C) or higher;[11]
  • severe nausea and vomiting;[11]
  • severe belly pain that does not go away;[11]
  • vaginal bleeding or leaking fluid;[11]
  • thoughts of harming yourself or the baby.[11]

MedlinePlus says some people spot in early pregnancy and do not miscarry, but any bleeding should prompt a call to a provider.[12]

Questions families ask

Which trimester is week 7?

OWH places week 7 in the first trimester.[1] The NHS guide places it in the first trimester.[2] ACOG places it in the first trimester.[4]

How big is the baby at 7 weeks?

The NHS says the baby is around 10 mm long from head to bottom.[3]

How is my due date worked out?

ACOG's Committee Opinion 700 says the due date is, by convention, 280 days after the first day of the last period.[7] The NHS says a dating scan at 8 to 14 weeks gives a more accurate date.[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). 7 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. NHS (United Kingdom). 4 weeks pregnant guide. Checked October 24, 2026.
  6. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH). What happens during prenatal visits?. Checked October 24, 2026.
  7. American College of Obstetricians and Gynecologists (with AIUM and SMFM). Methods for Estimating the Due Date (Committee Opinion No. 700; reaffirmed 2025). Checked October 24, 2026.
  8. Centers for Disease Control and Prevention. Medicine and Pregnancy: 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. Centers for Disease Control and Prevention (HEAR HER campaign). Urgent Maternal Warning Signs and Symptoms. Checked October 24, 2026.
  12. MedlinePlus (National Library of Medicine). Miscarriage. Checked October 24, 2026.