Background: Umbilical cord length is routinely recorded after delivery but seldom considered before it, despite growing evidence that both short and long cords carry obstetric risk.

Objective: To review the association between umbilical cord length and adverse obstetric outcomes, examine the biological mechanisms underlying it, and assess whether cord length can be evaluated antenatally.

Methods: A narrative review of the literature on cord length, morphometry, coiling and cord accidents, drawing on population registries, cohort and autopsy series, and ultrasound and artificial-intelligence studies, appraised for definitions, measurement timing and confounding.

Result: Adverse outcomes cluster at both extremes rather than rising linearly. Short cords were associated with caesarean delivery (38.8%), fetal distress (29.9%) and neonatal intensive care unit (NICU) admission (16.4%), with unplanned caesarean risk increasing progressively as length falls and placental abruption raised in term births (OR 1.98, 95% CI 1.72–2.73). Long cords act chiefly through mechanical opportunity, increasing wrapping, looping and knotting. Cord accidents accounted for 10% of possible or probable stillbirth causes, more commonly beyond 32 weeks, though published estimates vary widely. Lean cords occurred in 73.8% of IUGR fetuses versus 11.3% of normally grown fetuses. Absolute length is measurable only in the first trimester (r² = 0.89); three-dimensional estimation does not predict it, whereas coiling, diameter and insertion are assessable in routine examinations.

Conclusion: Cord length is best understood as a marker of fetal movement, placental development and the intrauterine environment rather than a single pathological variable. Routine measurement is not yet justified; a composite assessment of cord morphology, supported by standardised definitions and prospective cohorts, offers the more realistic path forward.