Weight gain is usually between 10-20 kg, and a weight gain of 11.5-16 kg is recommended for women with a normal pre-pregnancy BMI (Institute of Medicine of the US National Academy of Sciences, 1990).

Weight is gained as a result of the growth of the fetus, placenta and amniotic fluid, and enlargement of the following maternal organs and body compartments:

Fig 1 The same woman shown at 16, 20, 28 and 32 weeks