Fig. 5

The factors affecting circadian rhythm of vaginal delivery. SVD, Spontaneous Vaginal Delivery; NAD, Neuroaxial Analgesia Delivery. a1. Distribution of birth time in parturients without induction, n (SVD) = 2585; n (NAD) = 2623; a2. Distribution of birth time in parturients with induction, n (SVD) = 469; n (NAD) = 431; b1. Distribution of birth time in parturients without oxytocin, n (SVD) = 2428; n (NAD) = 2457; b2. Distribution of birth time in parturients with oxytocin, n (SVD) = 626; n (NAD) = 597; c1. Distribution of birth time in parturients without assisted operation, n (SVD) = 3005; n (NAD) = 2996; c2. Distribution of birth time in parturients with assisted operation, n (SVD) = 49; n (NAD) = 58