We used commonly used definitions for maternal age, marital status, and education.29 (link) We classified maternal complications into mutually exclusive categories of direct obstetric complications and medical diseases. Direct obstetric complications included uterine rupture, placenta praevia, abruptio placentae, unspecified antepartum haemorrhage, pre-eclampsia, eclampsia, HELLP syndrome, or any fetal malpresentation (breech, shoulder, or other). Medical diseases included heart disease, embolism/thrombophlebitis, hepatic disease, severe anaemia (haemoglobin <70 g/L), renal disease (including urinary tract infection), lung disease (including upper respiratory tract infection), HIV/AIDS, connective tissue disorders, gestational diabetes mellitus, and cancer.
We categorised women into risk groups for caesarean section using a modified version of the Robson classification.31 (link)
32 (link) Because there is no agreement on the optimal caesarean section rate in the population, and indications for caesarean sections are not standardised, Robson proposed a system that classifies women into 10 groups based on their obstetric characteristics (parity, previous caesarean section, gestational age, onset of labour, fetal presentation, and number of fetuses).31 (link) The size of each group and the caesarean section rate within each group correspond to an expected range. Monitoring caesarean sections within the Robson groups therefore allows the evaluation of clinical practice, including whether the caesarean section rate is justified. We adapted Robson’s classification because the NMNMSS did not collect information on whether or not the labour was induced. We created eight mutually exclusive categories: nulliparous, singleton, cephalic, ≥37 weeks’ gestation; multiparous, singleton, cephalic, ≥37 weeks’ gestation without a uterine scar; uterine scar, singleton, cephalic, ≥37 weeks’ gestation; all nulliparous women with a singleton breech; all multiparous women with a singleton breech, including those with a uterine scar; all multiple pregnancies, including those with uterine scar; all women with a single pregnancy in other abnormal lie, including those with uterine scar; and all singleton, cephalic, ≤36 weeks’ gestation pregnancies, including those with uterine scar.
For the institutional data we calculated the number of obstetricians per 1000 births using the number of births reported in the NMNMSS in 2015. We also report the region in which the hospital is located, using China’s standard definitions for region (western, central, and eastern).33 We extracted the day of the week from the date of delivery.
We report the number of perinatal deaths (stillbirths and early neonatal deaths within seven days of delivery before discharge), pregnancy related deaths, and uterine rupture. Stillbirths were defined as reported previously.29 (link) Pregnancy related deaths were defined as deaths from any cause in women who died after 28 completed weeks of gestation or with a fetus of birth weight 1000 g or higher (including women who died undelivered). Uterine rupture was defined as uterine or lower uterine dehiscence in late pregnancy or during childbirth, including complete and incomplete rupture.34
We categorised women into risk groups for caesarean section using a modified version of the Robson classification.31 (link)
32 (link) Because there is no agreement on the optimal caesarean section rate in the population, and indications for caesarean sections are not standardised, Robson proposed a system that classifies women into 10 groups based on their obstetric characteristics (parity, previous caesarean section, gestational age, onset of labour, fetal presentation, and number of fetuses).31 (link) The size of each group and the caesarean section rate within each group correspond to an expected range. Monitoring caesarean sections within the Robson groups therefore allows the evaluation of clinical practice, including whether the caesarean section rate is justified. We adapted Robson’s classification because the NMNMSS did not collect information on whether or not the labour was induced. We created eight mutually exclusive categories: nulliparous, singleton, cephalic, ≥37 weeks’ gestation; multiparous, singleton, cephalic, ≥37 weeks’ gestation without a uterine scar; uterine scar, singleton, cephalic, ≥37 weeks’ gestation; all nulliparous women with a singleton breech; all multiparous women with a singleton breech, including those with a uterine scar; all multiple pregnancies, including those with uterine scar; all women with a single pregnancy in other abnormal lie, including those with uterine scar; and all singleton, cephalic, ≤36 weeks’ gestation pregnancies, including those with uterine scar.
For the institutional data we calculated the number of obstetricians per 1000 births using the number of births reported in the NMNMSS in 2015. We also report the region in which the hospital is located, using China’s standard definitions for region (western, central, and eastern).33 We extracted the day of the week from the date of delivery.
We report the number of perinatal deaths (stillbirths and early neonatal deaths within seven days of delivery before discharge), pregnancy related deaths, and uterine rupture. Stillbirths were defined as reported previously.29 (link) Pregnancy related deaths were defined as deaths from any cause in women who died after 28 completed weeks of gestation or with a fetus of birth weight 1000 g or higher (including women who died undelivered). Uterine rupture was defined as uterine or lower uterine dehiscence in late pregnancy or during childbirth, including complete and incomplete rupture.34
