Results
In our Unit, in the period from 1996 to 2019 there were 42 016 births. In 32 360 women (77%) all the variables needed for the TGCS were recorded: 1769 (5.5%) women belonged to Groups 2B, 4B, 6, 7, 8 and 9 and were therefore excluded from analysis. Thus, a total of 30 591 deliveries are included in our analysis: 9236 in Group 1 (28.5%); 4717 (14.6%) in Group 2A; 8784 (27.1%) in Group 3; 2560 (7.9%) in Group 4A; 1847 (5.7%) in Group 10 and 3447 (10.7%) in Group 5. In this latter Group, 887 women (25.7%) attempted TOLAC. Maternal characteristics and type of delivery related to the entire population according to Robson Groups are listed in Table 1. Among immigrants 36.2% were from Africa, 23.3% from Eastern Europe, 22.0% from Asia, 18.0% from South-America. In our institution from 1996 to 2019 the CS rate was stable in groups 1 (6.2 ± 2.0%), 3 (1.8 ± 0.7%), 4A (4.1 ± 2.2%), while it decreased in groups 2A (from 27.9% in 2000 to 19.9% in 2019, F=0.03), 5 (from 94.2% in 1998 to 75.3% in 2019, F<0.0001) and 10 (from 58.9% in 2000 to 28.3% in 2019, F<0.0001) (Figure S1). Perinatal mortality (i.e. the number of stillbirths from 28 weeks and deaths in the first week of life) was 3‰ (97 cases) and it remained stable throughout the study period.
Table 2 reports the results of the binomial logistic regression, including odds ratio (OR), 95% confidence interval (CI) and p-value.
The age of the woman greater than or equal to 40 appears to be a risk factor (RF) for CS in all groups except 5 and 10. The presence of pregestational-gestational diabetes is a RF for CS only in Groups 1 and 5. Not surprisingly, gestational hypertension is a RF for CS in preterm pregnancies (Group 10) and in nulliparous induced (Group 2A), but also in Group 5. Obesity represents a RF for CS in nulliparous (Groups 1 and 2A) whilst is protective in Group 5. The presence of a neonatal weight >4000 is a RF for CS in nulliparous (Group 1), especially when induced (Group 2A), and multiparous in spontaneous labour (Group 3). Obstetric analgesia is protective against CS in nulliparous induced (Group 2A), women in TOL (Group 5) and preterm (Group 10).
Being immigrant was a RF for CS in multiparous induced (Group 4A) while it was protective in nulliparous in spontaneous labour (Group 1) and preterm (Group 10).