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You and your baby at 5 weeks pregnant - Your pregnancy and baby guide

Your baby at 5 weeks

The baby's nervous system is already developing, and the foundations for its major organs are in place. At this stage, the embryo is around 2mm long.

The heart is forming as a simple tube-like structure. The baby already has some of its own blood vessels and blood begins to circulate.

A string of these blood vessels connects the baby and mother, and will become the umbilical cord.

At the same time, the embryo's outer layer of cells develops a groove and folds to form a hollow tube called the neural tube. This will become the baby's brain and spinal cord.

Defects in one end (the "tail end") of the neural tube lead to spina bifida. Defects in the "head end" lead to anencephaly, when the bones of the skull do not form properly.

Folic acid prevents spina bifida. You should start taking it as soon as you find out you're pregnant (even before you get pregnant, if possible).

You at 5 weeks

This is the time of the first missed period, when most women are only just beginning to think they may be pregnant. 

Find out what to expect on your NHS pregnancy journey.

Antenatal care (also called pregnancy or maternity care) is the care you get from midwives and doctors during your pregnancy to make sure you and your baby are as well as possible.

Contact your GP or your preferred maternity service promptly once you know you're pregnant so you start getting care at the right time. They'll arrange your first midwife appointment.

Find maternity services near you

Starting your maternity care early in pregnancy is important if you have a health condition that may affect your pregnancy, such as heart or lung conditions, epilepsy, mental health problems, diabetes or asthma.

Your doctor or midwife will be able to advise you if you're taking medicines for your condition while you're pregnant, and provide the specialist care you and your baby need.

Do not stop taking any prescribed medicine without checking with your doctor or midwife first.

Things to think about

The Start4Life site has more about you and your baby at 5 weeks of pregnancy.

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See 3 to 42 weeks of pregnancy

Media last reviewed: 27 February 2017
Media review due: 17 March 2020

Page last reviewed: 17 July 2018
Next review due: 17 July 2021