4 weeks and 4 days pregnant

The embryo, viewed from above here, has a subtle groove (the primitive groove) and a small central depression (the primitive node), both seen here in white. These changes start at what will become the base of the spine and progress towards the head.

You’re probably eager to know when your baby will be born. The chart below will tell you the expected date of delivery.

Until you have a dating scan in a few weeks’ time, your baby’s due date will be calculated by counting 280 days from the first day of your last menstrual period. At the dating scan, your baby will be measured and his age calculated. The scan date will then be used as it is considered to be accurate.

While you’re bound to want to know the due date, try not to get too fixated on it. Most babies are born within about two weeks of their due dates but your baby will be considered to be born at term if you give birth between 37 and 42 weeks. So your estimated delivery date is just that, an estimate; your baby may be born earlier or later.

To work out your expected date of delivery (EDD) – also known as the due date – you need to know when you started your last menstrual period (LMP). Find your LMP date on the chart below to discover when your baby is expected. For example, if your last LMP was 13 January, then your baby will be due on 20 October.