We used reliable methods to assess the quality of the evidence and looked at seven key outcomes: preterm birth (birth before 37 weeks of pregnancy); the risk of losing the baby in pregnancy or in the first month after birth; spontaneous
vaginal birth (when labour was not induced and birth not assisted by forceps; caesarean birth; instrumental
vaginal birth (births using forceps or
ventouse); whether the perineum remained intact, and use of regional analgesia (such as epidural).