Our study showed that the rates of VBAC rates increased during the relaxation of the one-child policy. We found increasing trends for women older than 25 years, for women with one previous caesarean section and in level-2 hospitals. The absolute rates of severe maternal morbidity and mortality were low among women who had a VBAC and those who had a RCD. However, relative rates of serious neonatal morbidity and mortality were substantially higher in VBAC. Between 2013 and 2016, the proportion of pregnant women with a previous caesarean section in Hebei province increased from 13.8%(7,333/52,968) to 22.5%(14245/63218), and reached 26.3% (14,416/54,715) by 2017, which was higher than the average level of China18. This could be explained by the large number of women with a previous caesarean section and the increase in number of women wanting to have a second child after universal two-child policy18. In 2017, 54.7% (29,945/54,715) of participants were multiparas. It suggested that the RCD rates would increase in China after years of high cesarean section rate, if VBAC were not taken. Studies from several countries also have shown that VBAC is an elective measure for reducing RCD rates19,20,21. Despite the debate in China whether to support VBAC as a measure to reduce the caesarean section rates22,23,24, some hospitals have encouraged trial of labour after caesarean section since 201017,25. This promotion of VBAC has been done to achieve reduction in the caesarean section rates and to act as maternal requirements with a prior caesarean section. Surprisingly, we found that the rate of VABC in level-2 hospitals was higher than that in level-3 hospitals. Considered that it may be related to referral of pregnant and lying-in women with complications in lower-level hospitals. The change of population policy to universal two-child policy shows an opportunity to promote VBAC in China. But to ensure the safety of mothers and their newborns, we mostly choose to have another cesarean section. So it's clear that the VBAC rates in level-2 hospitals increased from 5.5–7.1%, but declined to 5.8% by 2017. Compared with developed country, the VBAC rates in China seems to have a potential to further increase26,27,28.
However, women in China with a previous caesarean section still have limited choices for a preferred delivery mode. In general, it appears that clinicians easily opt for repeat CS. Most obstetricians worried about been sued for adverse outcomes and bear the loss of income, so they may be reluctant to implement VBAC in their wards29,30, with the risk of uterine rupture, operative injury, fetal or neonatal death31,32. In our study, the maternal morbidity and mortality of VBAC was very low, such as 1.2‰ of uterine rupture, which was in contrast to other studies(16.8‰)33. It suggested that VBAC was a safe mode of delivery, if master the indications and observe closely.
A cohort study in the UK also confirmed that the complications was reduced by vaginal compression of the fetus, such as wet lung and respiratory distress syndrome that caused by excessive retention of pulmonary fluid, and long-term asthma of newborns delivered by elective cesarean section was significantly increased (HR: 1.24, 95% CI: 1.09–1.42) 34. Therefore, it is very necessary to have a trial of labor after cesarean(TOLAC), as Young 31. There were higher rates of perinatal adverse outcomes in women with VBAC than who with RCD. We found a significant increase in the rate of intrapartum stillbirths among the infants of women who underwent VBAC(12.9‰) as compared with infants born after RCD(0.6‰). It was necessary that neonatologists involve to the process of trial of labour after caesarean section, to ensure the timely treatment for perinatal adverse outcomes14.
Strengths and limitations: The HBMNMSS was a well established surveillance system with rigorous quality controls, involved 22 hospitals, covering a large sample, the results still have value for the choice of delivery mode. But we could not obtain the information of women undergoing TOLAC and failed, no information of VBAC after elective cesarean section or emergency cesarean section, it might be a bias in outcomes of VBAC.