By the time you reach your due date, just over a third of your extra weight will come from your baby, the placenta and amniotic fluid.

Every mum and baby is different, but here are some averages:

At birth, a baby weighs about 3.3kg (7.3lb).

The placenta, which keeps your baby nourished, weighs 0.7kg (1.5lb).

The amniotic fluid, which supports and cushions your baby, weighs 0.8kg (1.8lb).

The other two thirds of extra weight is due to the changes that happen to your body while you're pregnant.

On average:

The muscle layer of your womb (uterus) grows dramatically, and weighs an extra 0.9kg (2lb).

Your blood volume increases, and weighs an extra 1.2kg (2.6lb).

You have extra fluid in your body, weighing about 1.2kg (2.6lb).

Your breasts weigh an extra 0.4kg (0.9lb).

You store fat, about 4kg (8.8lb), to give you energy for breastfeeding.