Pregnancy physiology
During pregnancy, the maternal cardiovascular, renal and endocrine systems adapt to support fetal growth. The placenta is the principal exchange interface between maternal and fetal circulations.
Open interactive lesson & self-check ↗Maternal–fetal exchange across placenta
Original conceptual SVG · scalableMaternal and fetal blood normally remain in distinct compartments; exchange occurs across the placental barrier.
Circulations remain distinct
Maternal blood enters the intervillous space and fetal blood flows through villous capillaries. Gases, nutrients, wastes and selected molecules cross the placental barrier without normal direct mixing of whole circulations.
Maternal adaptation
Plasma volume and cardiac output typically rise. Renal plasma flow and glomerular filtration also change, so nonpregnant reference intervals may not apply.
Placental endocrine function
The placenta produces hormones that help maintain pregnancy and alter maternal metabolism.
Reference and next reading
Explore the original curriculum and publisher-hosted resources for full-depth reading; this note is an original schematic introduction, not an exhaustive chapter.