What happens to my weight during pregnancy?

Weight gain in pregnancy is variable, but in general there is an increase in weight of approximately 12 kg. As many women experience nausea and/or vomiting in early pregnancy (generally from 5-13 weeks of pregnancy), it is not uncommon to lose weight at this stage of pregnancy. Generally, after this stage of pregnancy weight gain is progressive up to the last 2 weeks when it becomes static.

The weight gained is made up of the following;

  1. The baby – on average 3.5 kg
  2. The placenta (after birth) – 0.5kg approx.
  3. The liquor (fluid around the baby) – 1kg approx.
  4. The uterus (womb) – 1kg approx.
  5. The enlargement of the breasts – 0.4 kg approx.
  6. Accumulation of fat (mainly) and protein – 3.5 kg approx.
  7. Increase in blood volume – 1 kg approx.
  8. Increase in body fluid (up to 80% of women have oedema in pregnancy) – 1kg approx.

Previously all women were weighed at each antenatal visit, however this in practice only happens for women who have diabetes in pregnancy. The reason that we don’t now weigh women at every visit is because the average birth weight seen in times of want over times of plenty (e.g. in Holland during the second world war) was only 300g less approximately. This means that the baby takes what he or she needs to develop during the pregnancy regardless of the mother to be. We can now gain much more direct information using ultrasound examinations in pregnancy rather than using weight as a surrogate marker for pregnancy problems.