Figure 1.

Cervical dilatation curves of primiparous and multiparous females with 90% reference intervals. A. Primiparous females. B. Multiparous females (parity=1). C. Multiparous females (parity ≥ 2). Primiparous labor curve consists of 4339 vaginal examinations [coefficient of determination (R²) = 0.71] and multiparous labor curves consist of 3439 (parity = 1, R² = 0.75) and 3459 (parity ≥ 2, R² = 0.73) vaginal examinations, respectively. Dots are data, the solid lines are the fitted curves and dotted lines are the 90% reference intervals.