Maternal complications
The main variable exposed in our analysis was gestational age at
delivery. The maternal complications were mainly episiotomy,
instrumental delivery, intrapartum
caesarean section (ICS), postpartum haemorrhage (PPH), shoulder
dystocia, obstetric anal sphincter injury (OASIS),
meconium-stained amniotic fluid
(MSAF), intrapartum cervical laceration, epidural analgesia, amniotic
fluid embolism and labour progression duration. An episiotomy performed
at the time of crowning was defined as a surgical incision made to widen
the vaginal opening for the delivery of the foetus11.
Instrumental delivery was defined as vacuum extraction or forceps
delivery12. In our hospital, it mainly referred to
vacuum extraction. An international uniform standard of labour onset has
not been established. Based on our combined physician experience, we
defined ICS as emergency caesarean after regular uterine contractions,
cervical canal flattening and cervix opening by 2+ cm for women who were
attempting a vaginal delivery. According to the medical indication, the
cephalopelvic disproportion group and foetal distress group were mainly
compared. PPH was defined as blood
loss in excess of 500 ml after vaginal delivery and in excess of 1000 ml
after caesarean delivery in the first 24 hours after labour, and it was
divided into mild PPH (estimated blood loss > 500 ml) and
severe PPH (estimated blood loss > 1000
ml)13. The total amount of blood loss was measured by
weighing soaked materials and by use of the suction system and collector
bags in the operating room. Shoulder dystocia was defined as the
inability of the foetus to be delivered by traditional midwifery methods
when the symphysis pubis obstructed the anterior descending of the
shoulder or the posterior shoulder of the foetus was impacted on the
maternal sacral promontory14. OASIS, including third-
and fourth-degree vaginal tears, damages the anal sphincter complex and
anorectal mucosa15. Intrapartum cervical laceration
was defined as laceration with abnormal vaginal bleeding or requiring
cervical suturing16. Amniotic fluid embolism was
defined as the abnormal activation of proinflammatory mediator systems
triggered by entrance into the maternal circulation of material from the
foetal compartment17. The first stage of labour was
defined as beginning from maternal perception of regular contractions to
dilation. The second stage of labour was defined as the time from full
dilation to delivery of the neonate3.