Pregnancy Month 1

Overview of month 1

The first month of pregnancy is unusual: for about half of it, you are not actually pregnant yet. Pregnancy is dated from the first day of the last period, so month 1 includes your period, ovulation around week 2, conception, and implantation in weeks 3 to 4. Most people only discover they are pregnant at the very end of this month, when a period is missed.

Weeks in pregnancy month 1

Your baby in month 1

After fertilisation, the single cell divides rapidly as it travels down the fallopian tube, reaching the uterus as a ball of cells called a blastocyst. By the end of week 4 it has implanted into the uterine lining and begun to form the layers that will become every organ, along with the early placenta.

Your body in month 1

There may be no symptoms at all. Some people notice light implantation spotting, mild cramping, breast tenderness or tiredness towards the end of the month.

Care during month 1

Taking folic acid before and in early pregnancy is a standard general recommendation. If a test is positive, contacting a doctor or midwife to book a first appointment is a common next step. Schedules vary between countries and providers; your own care team will tell you what applies to you.

Why pregnancy months are approximate

A 40-week pregnancy does not divide evenly into nine calendar months: each calendar month is about 4.3 weeks, so nine months is roughly 39 weeks, and the due date falls a week or so later. Different books and apps therefore group weeks into months slightly differently. This site uses the common grouping in which month 1 spans about weeks 1 to 4. When you talk to a healthcare professional, you will hear weeks and days — for example “1 weeks and 2 days” — because that is far more precise. To see exactly where you are, use the Pregnancy Week Calculator.