Physiological changes in pregnancy: uterus, vagina, cardiovascular system, blood, respiratory function

1. Big picture

Pregnancy is a controlled physiological stress test. The maternal body adapts to support:

Fetal growth → placental perfusion → preparation for labor → preparation for blood loss at delivery

For the exam, the key is to know what is normal in pregnancy and what is pathological.

The most important systems in this topic are:

Uterus → grows, contracts, increases blood flow
Vagina/cervix → vascular, soft, mucus-rich, infection-prone
Cardiovascular system → high-output, low-resistance circulation
Blood → physiological anemia + hypercoagulability
Respiration → increased ventilation + mild respiratory alkalosis

Core clinical principle:

Many symptoms in pregnancy are physiological,
but severe dyspnea, syncope, chest pain, hypertension, hypoxia, heavy bleeding, or fetal heart rate abnormality are never “just pregnancy.”

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