Study population
In 2020, a total of 6046 women were booked for delivery in our hospital and 1868 low-risk singleton deliveries at 40 0/7-41 6/7 weeks were included in the study. Of these, 299 pregnancies were excluded based on the following factors: elected caesarean delivery (n = 295), VBAC (n = 3) and partial data loss (n = 1). Ultimately, a total of 1569 pregnancies met the inclusion criteria. Among them, 1107 (71%) pregnancies delivered at 40 0/7-40 6/7 weeks and 462 (29%) delivered at 41 0/7-41 6/7 weeks (Fig. 1).
Maternal characteristics in the study groups are compared in Table 1. A total of 1262 (approximately 80%) were nulliparous, and 73 (<5%) were assisted reproductive pregnancies. Approximately 60% of women had complications, including anaemia, hypothyroidism, diabetes and other unusual complications. Statistical significance was not observed in the cases of anaemia or hypothyroidism between the two groups. The risk of premature rupture of membranes (PROM) in the full-term group was significantly higher than that in the late-term group (22% versus 12%, P<0.001). The prevalence rate of gestational diabetes mellitus (GDM) in the full-term group was significantly higher than that in the late-term group (16% versus 8%, P<0.001).
Different modes of labour are compared in Table 2. The spontaneous labour rate was significantly higher than that in the late-term group (54% versus 20%, P<0.001). The full-term group was lower than the late-term group in terms of the rate of induction of balloon catheter combined with oxytocin (BCCO) (9% versus 46%, P<0.001), the rate of oxytocin induction (22% versus 27%, P=0.012) and artificial rupture of membrane (AROM) induction (21% versus 31%, P<0.001). The Bishop score of parturients with BCCO induction was not statistically significant (P=0.055). However, the late-term group had a higher final vaginal delivery rate of BCCO (88% versus 79%, P=0.049) and AROM (83% versus 71%, P=0.006). Significant differences were not observed in the vaginal delivery rate of oxytocin induction (80% versus 76%, P=0.431).