What happens to a woman when she is pregnant

Me, when I was pregnant

Pregnancy is that period of time in which a new life develops inside a woman’s body.

As all mothers know, pregnancy is characterized by A LOT of changes in our body, both anatomical and physiological.

Here is a (partial) list of changes which women experience during pregnancy.

  • Plasma volume. It increases of about 1.5 L during the whole pregnancy. The number of red blood cell increases at a lower rate than plasma volume, causing a fall in hemoglobin concentration.
  • Micro-nutrients necessity. During pregnancy the requirement for iron and vitamin B12 increases 2 to 3 times and for folic acid (vitamin B9) 10 to 20 times.
  • Cardiac changes. Hearth is put under stress during gestation. At 8 weeks the cardiac output is increased by 20%. The supine position causes a reduction in venous return, therefore pregnant women should lay in the left or right position.
  • Respiratory changes. The demand of oxygen increases greatly during pregnancy due both to the increase in the metabolic rate and in the consumption of oxygen.
  • Renal function. Kidneys increase of about 1.5 cm. Changes of the sympathetic nervous system cause sodium and water retention (aka cellulite and swollen feet).
  • Alimentary trait. Nausea and vomiting typical of the first trimester could be an evolutionary mechanism preventing women from eating teratogenic food. Glucose metabolism changes causes in some women pregnancy diabetes. Lipid metabolism changes and the body accumulate fat as storage for mother’s energy.
  • Progesterone. It is the most important hormone during gestation. It reduces urethral tone and peristalsis (aka we pee ourselves when we sneeze), can cause teeth pain and gastroesophageal reflux.


Soma-Pillay et al., “Physiological changes in pregnancy”, (2016), 10.5830/CVJA-2016-021

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