Risk of adverse maternal and infant outcomes after assisted vaginal delivery compared with unassisted vaginal for 158,241a WA vaginal births.

aRestricted to vaginal, singleton, term births (37–41 completed weeks), where the infant was live born and without birth defects.bAdjusted for year of birth, maternal age, parity, patient status (not in stratified analysis), hospital type (private/public/tertiary), smoking during pregnancy, marital status, ethnicity (Caucasian/Indigenous/other), pre-existing medical conditions (asthma/hypertension/diabestes), SES quintiles, residential remoteness, gestation, infant weight, pregnancy complications, labour and delivery complications, analgesia during labour (none/gas or intramuscular/epidural/spinal), and whether the labour was induced.cApgar score at 5 minutes = 0–6.dEndotracheal intubation or external cardiac massage.