Number of cases within denominator resulting in:

• caesarean section
• vaginal delivery

Total number of women with a low-risk delivery in Ontario.

Inclusions:

• Robson criteria 1 to 4:
• Robson 1: Nullipara (first time mothers) who had singleton, full-term (gestational age ≥37 weeks), and cephalic (head first) delivery with spontaneous labour
• Robson 2: Nullipara (first time mothers) who had singleton, full-term (gestational age ≥37 weeks), and cephalic (head first) delivery with induced labour or caesarean section before labour
• Robson 3: Multipara (women who have given birth before) who had singleton, full-term (gestational age ≥37 weeks), and cephalic (head first) delivery with spontaneous labour
• Robson 4: Multipara (women who have given birth before) who had singleton, full-term (gestational age ≥37 weeks), and cephalic (head first) delivery with induced labour or caesarean section before labour

Exclusions:

• Autoimmune - lupus; rheumatoid arthritis; autoimmune other
• Cancer - diagnosed in pregnancy; medication exposure in pregnancy-chemotherapeutic agents
• Maternal cardiovascular - acquired heart disease; antihypertensive therapy outside of pregnancy; cardiovascular disease; congenital heart defect; congenital heart disease ; pre-existing hypertension; renal disease; other cardiovascular
• Diabetes - diabetes and pregnancy
• Gastrointestinal - liver/ gallbladder - cholecystitis; colitis; crohn’s; hepatitis; liver/ gallbladder - intrahepatic cholestasis of pregnancy;
• Genitourinary - acquired renal (insufficiency; chronic infections); congenital/ genetic renal (renal agenesis; pelvic kidney); renal disease; uterine anomalies; genitourinary other
• Maternal haemotology - gestational thrombocytopenia; haemophilia (a; b von willebrand); idiopathic thrombocytopenia; sickle cell disease; thalassemia; thrombophilia; haematology other
• Hypertensive disorders in pregnancy - gestational hypertension; eclampsia; hellp; preeclampsia; preeclampsia requiring magnesium sulfate; pre-existing hypertension with superimposed preeclampsia; maternal unknown
• Musculoskeletal - muscular dystrophy/ neuromuscular disorder; myotonic dystrophy; osteogenesis imperfecta; achondroplasia; musculoskeletal other
• Neurology - cerebral palsy; multiple sclerosis; myasthenia gravis; spina bifida/ neural tube defect; neurology other
• Placental - placenta accreta; placenta increta; placenta percreta; placenta previa; placental abruption; placental other
• Fetal complications - anomalies; isoimmunization/ alloimmunization; intrauterine growth restriction; oligohydramnios; fetal therapy – fetal surgery
• Fetal genetic anomalies -cgh microarray abnormality polymorphism; chromosome abnormality; other birth defects; other genetic inherited disorders/ syndromes