🤰 3 Weeks Pregnant

You are in week 3 of your pregnancy — the first trimester, month 1. Fertilisation happens in the fallopian tube. The fertilised egg (zygote) divides as it travels to the womb.

By the Power Calculators team Updated 5 Nov 2026

TrimesterFirst

MonthMonth 1

Weeks to due date37

Your baby at 3 weeks

Fertilisation happens in the fallopian tube. The fertilised egg (zygote) divides as it travels to the womb.
Your baby's sex and genes are set at the moment of fertilisation.

Days completed	21 of 280 (8%)

Your body at 3 weeks

Nothing feels different yet for most women.

To do this week

Keep taking folic acid. Avoid unprescribed medicines, X-rays and high-dose vitamin A.

When to call your doctor

Vaginal bleeding or fluid leaking
Severe tummy pain or cramping
Fever over 38 °C
Severe headache, blurred vision or sudden swelling of face or hands
Vomiting so much you cannot keep fluids down

Pregnancy Due Date Calculator

Find your estimated due date, conception date and how far along you are, from the first day of your last period.

Pregnancy Week Calculator

Find exactly how many weeks and days pregnant you are today, your trimester and your due date.

When to Take a Pregnancy Test Calculator

Find the earliest day to take a pregnancy test and the most accurate day, from your last period and cycle length, with implantation dates and test accuracy by day.

Frequently asked questions

How many months is 3 weeks pregnant?

3 weeks is in month 1 of pregnancy as months are usually counted (about 0.7 calendar months since your last period), in the first trimester.

What should I do at 3 weeks pregnant?

Keep taking folic acid. Avoid unprescribed medicines, X-rays and high-dose vitamin A.