birthdate.baby Week

Week by week  /  First trimester

Week 1

Your baby is not measurable yet. Here is what is happening, what you might feel, and the two or three things worth doing this week.

Size right now

Too early to measure

Trimester
First
To go
39 weeks

The baby

Nothing yet. This week is your period. Pregnancy is dated from the first day of it, which means the first two weeks of a 40 week pregnancy happen before there is anything to be pregnant with. It is an odd convention and it is the one every doctor uses.

You

A normal period. If you are trying to conceive, this is the week to start a prenatal vitamin with folic acid, because the neural tube closes before most people know they are pregnant.

This week

Start a prenatal vitamin with at least 400mcg of folic acid
Note the first day of this period, every date from here is counted from it

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Week 2 lands in your inbox when you get there

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Averages, not targets. Babies vary a great deal and a scan that reads differently from this page is not a problem. Anything that worries you is a call to your midwife or doctor, not a search.