Illustration of a baby at week 7 inside the womb in cross-section, with the umbilical cord and yolk sac — Womb in cross-section, enlarged to show detail. Not true size.

First trimester, week 7

7 weeks pregnant: Paddle hands and a busy brain

Size of a: Blueberry
Length: ≈ 10 mm crown to rump
Weight: < 1 g
Heart rate: 120–160 bpm typical range
Due date: 231 days away 18% of the way

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Checked against the sources listed on this page. Not reviewed by a clinician. Last updated 5 November 2026. How we check.

At 7 weeks pregnant, your baby is about the size of a blueberry: roughly 10 mm from crown to rump, weighing less than 1 g. You’re in your first trimester, with about 33 weeks to go until your due date.

Your baby this week

The arm buds flatten into paddle-shaped hand plates. The leg buds are catching up.
The brain is growing fast and is divided into forebrain, midbrain and hindbrain.
Nostrils begin as small pits, and the eye lens is forming.

Your body this week

Your uterus is about the size of a lemon, although your belly usually doesn’t show yet.
Increased saliva, a metallic taste and constipation are common and caused by hormones.
Fatigue can feel intense. Your body is building a placenta and you are making far more blood.

Typical weight gain so far: 0.3–1 kg
Your uterus: About the size of a lemon

Weight gain range is for a pre-pregnancy BMI of 18.5–24.9 (IOM guideline). Your provider may advise differently.

Scans, tests and checkups

This week

First prenatal visit & bloodwork Checkup
Health history, blood pressure, urine, blood type and Rh factor, blood count, and infection screening (hepatitis B, HIV, syphilis, rubella immunity). The UK aims to see you by 10 weeks.
This week

Early / dating ultrasound Ultrasound
Confirms the pregnancy is in the uterus, sees the heartbeat, counts babies and dates the pregnancy. Often part of the first visit or combined with the 12-week scan.
From week 10

NIPT (cell-free DNA blood test) Blood test
A blood test that screens for Down syndrome (trisomy 21), trisomies 18 and 13, and can report sex chromosomes. It is a screening test. A high-chance result is confirmed with CVS or amniocentesis.

Baby’s sex: Sex from ~10 weeks, typically >98–99% accurate
From week 10

CVS (chorionic villus sampling) Diagnostic
Diagnostic test on a tiny placenta sample, offered after a high-chance screening result or known family condition. The NHS gives the miscarriage risk as less than 1 in 200 for most pregnancies. The UK usually does it at 11–14 weeks.

Baby’s sex: Diagnostic, only done for medical reasons
From week 11

NT scan / 12-week scan Ultrasound
Measures the fluid at the back of the baby’s neck (nuchal translucency). Combined with blood hormones, it estimates the chance of chromosomal conditions. The window is about 11 weeks to 13 weeks 6 days.

See the full scan and test timeline

Real size, next to an adult hand

Adult hand 18.5 cmbaby 1 cm

Growth curve

Typical weight by week: WHO median from week 20, approximate before that. Healthy babies vary widely.

When to call your midwife or doctor at 7 weeks

Call your midwife, doctor or maternity unit straight away, day or night, if you have any of these:

Vaginal bleeding, with or without cramps.
Strong pain low on one side of your belly, pain at the tip of your shoulder, or feeling faint. These can be signs of an ectopic pregnancy, which needs urgent care.
Being sick so often that you can’t keep fluids down for a day.
Fever of 38 °C (100.4 °F) or higher, or pain or burning when you pee.
Pain or swelling in one leg, chest pain, or sudden shortness of breath. These can be signs of a blood clot.
Feeling very low, hopeless or anxious most days. If you feel you might harm yourself, get emergency help.

Based on NHS and ACOG guidance. This list isn’t complete. If something feels wrong, call anyway. In an emergency, call your local emergency number.

Tip for this week

Keep taking folic acid for the first 12 weeks. Vitamin D is also advised, at least through autumn and winter. Avoid cod liver oil and supplements containing vitamin A (retinol).

Common questions at this stage

All common questions

Questions people ask about week 7

How big is a baby at 7 weeks?

About 1 cm from crown to rump, roughly the size of a blueberry.

What is the heart rate at 7 weeks?

Typically around 120–160 beats per minute. It keeps climbing to a peak at about 9–10 weeks.

References

Advice differs between countries, so follow your own care team’s plan. Weights from week 20 are the WHO median, and earlier weights are approximate. How we check this.