Tool 02
Week
by week
Forty two pages, one per week. What is developing, what you are likely to feel, and the two or three things actually worth doing before the week is out.
You are here
Not sure which week you are in?
Enter one date and this page will open on the right one, here and every time you come back.
First trimester
Weeks 1 to 13. Mostly waiting, and one scan window that will not wait for you.
Second trimester
Weeks 14 to 27. The easy stretch, and the one where everything with a delivery time gets ordered.
Third trimester
Weeks 28 to 42. Appointments get frequent, the bag goes by the door at 35, and the date stops mattering.
One email a week
The week page, on the week you reach it
Same writing, no app, no notifications. One click to stop.
How the weeks are counted
Week 1 is the week of your last period, which means you are not pregnant during it. Conception happens somewhere in week 3, and most people find out in week 4 or 5. By the time a test turns positive you are usually already about four weeks pregnant on paper.
Doctors write gestational age as weeks and days, so 24w3d means twenty four completed weeks plus three days. On this site, "week 25" is the week you are living through when you are 24w3d. The two ways of saying it are one apart and both are correct, which is why the calculator shows you both.
Sizes and weights
The figures on each page are typical averages. Through week 20 the length is measured crown to rump, because the legs are curled and cannot be measured straight, and from week 21 it is crown to heel. That is why the number jumps between those two pages. It is not an error and your baby did not double in length overnight.
Real babies vary enormously. A scan that reads differently from these numbers is not a problem in itself, and anything that concerns you belongs with your midwife or doctor rather than with a table.