Maternal outcomes
Various maternal outcomes are presented in Table 2 . The low annual volume group had higher rates of any spontaneous perineal tears (32.3% vs 31.2%, p<0.01) with higher rates of spontaneous 1st and 2nd degree perineal tears (26.4% and 26.9% vs 25.6% and 25.8% p=0.05 and p=0.01 respectively). While, they had lower rates of episiotomy (33% vs. 36%, p<0.01), rates of 3rd and 4th degree perineal tears did not differ. The low annual volume group had higher rates of manual uterine exploration for suspected placental products (2.2% vs. 1.9%, p<0.01), yet rates of manual lysis of the placenta did not differ between the groups. No differences were noted for other maternal outcomes, including; shoulder dystocia, PPH, mean hemoglobin drop, blood products transfusions, endometritis, maternal ICU admissions and prolonged hospitalization.
Multivariate regressions adjusted for: maternal age, parity, TOLAC, oxytocin augmentation, persistent occipito-posterior presentation and CNMs’ practice duration, revealed no significant association between low annual volume and manual exploration of uterus aOR 1.06, 95% CI [0.97-1.15].