Minimum cord length that allows spontaneous vaginal delivery.

Objective: To determine the shortest umbilical cord length that will permit spontaneous vaginal delivery.

Methods: This prospective, observational study included 166 randomly chosen women with no apparent antepartum complications who delivered spontaneously at or beyond 37 weeks. The cord was clamped at the maternal introitus immediately after delivery. The cord segment was measured from introitus to placental insertion. We reviewed a recent fetal scan to identify the placental implantation site (fundal or lateral).

Results: The mean cord segment from placental insertion to maternal introitus measured 22.4 cm (95% CI 11-32). The segment was 2.1 cm longer (95% CI 0.4-3.7) when the placenta was implanted at the uterine fundus rather than laterally (p < 0.01, 1-sided t test). An excessively short cord segment (<13 cm) was present in 2 cases (1.2%) with lateral placental implantation. There were no cases of fundal implantation with an excessively short cord.

Conclusion: The uterine axis and birth canal are not long enough to prevent spontaneous vaginal delivery .in the presence of a short umbilical cord. Placental location does not impede delivery except perhaps when fundal in the presence of an excessively short cord.