Illustration of a baby at week 10 inside the womb in cross-section, with the placenta and umbilical cord — Womb in cross-section, enlarged to show detail. Not true size.

First trimester, week 10

10 weeks pregnant: Officially a fetus

Size of a: Strawberry
Length: 3.1 cm crown to rump
Weight: 4 g approximate
Heart rate: 150–180 bpm typical range
Due date: 210 days away 25% 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 10 weeks pregnant, your baby is about the size of a strawberry: roughly 3.1 cm from crown to rump, weighing about 4 g. You’re in your first trimester, with about 30 weeks to go until your due date.

Your baby this week

The embryonic period is over. From now on the baby is called a fetus, and growth rather than new structures takes centre stage.
Fingers and toes are fully separate, and nail beds begin to form.
Bones are starting to harden, and the kidneys may begin producing urine.

Your body this week

hCG levels are near their peak, which is why nausea and fatigue often feel strongest around now.
Your uterus is about the size of an orange.
Round ligament twinges, brief sharp pains low in the belly, may start as the uterus grows.

Typical weight gain so far: 0.4–1.5 kg
Your uterus: About the size of an orange

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

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
This week

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 3.1 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 10 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

If you want NIPT (a cell-free DNA blood test), it can be done from 10 weeks. It screens for Down syndrome and some other conditions, and can reveal sex chromosomes.

Myth or fact?

Does a heart rate over 140 mean it’s a girl?

Myth

No. Studies comparing early heart rates in boys and girls found no meaningful difference. Heart rate depends mostly on gestational age.

Read the evidence

Common questions at this stage

All common questions

More myths around week 10

Questions people ask about week 10

Can you find out the gender at 10 weeks?

Yes, with a blood test. NIPT (cell-free DNA) from 10 weeks can report the sex chromosomes with over 98–99% accuracy in most studies. Ultrasound can’t reliably show sex this early.

What is the difference between an embryo and a fetus?

Up to the end of week 10 (8 weeks after conception) it is called an embryo. After that, when all main structures have formed, it is called a fetus.

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.