Umbilical Cord & Placenta: Fetal‑Maternal Connection Explained

The umbilical cord connects the fetus to the placenta, serving as the lifeline for gas, nutrient, and waste exchange.

Structure

• Two umbilical arteries (carry deoxygenated blood, waste from fetus → placenta).
• One umbilical vein (carries oxygenated, nutrient‑rich blood from placenta → fetus).
• Embedded in Wharton’s jelly (mucoid connective tissue) protecting vessels from compression.

Development

Forms from the connecting stalk (extra‑embryonic mesoderm) incorporating yolk‑sac vessels and allantois. By week 12, functional placental circulation established.

Clinical Relevance

• Cord length, insertion (central, marginal, velamentous), and coiling index affect outcomes.
• Single umbilical artery (2‑vessel cord) associated with congenital anomalies (renal, cardiac, chromosomal).
• Delayed cord clamping (≥30‑60 s) improves neonatal iron stores and transition.