Table 1 Factors used to define the early pregnancy complicating factors and uncomplicated pregnancy composite measures

Pre-existing medical co-morbidities:

• Autoimmune conditions e.g., lupus

• Cardiovascular conditions e.g., congenital or acquired heart disease, pre-existing hypertension

• Type 1 or 2 diabetes

• Endocrine e.g., hyperthyroidism

• Gastrointestinal e.g., inflammatory bowel disease, hepatitis

• Renal disease

• Haematology e.g., sickle cell disease, thrombophilia

• Neurology e.g., epilepsy

• Pulmonary e.g., cystic fibrosis, previous pulmonary embolism

• Psychiatric e.g., Bipolar disorder, schizophrenia

• Infectious disease e.g., active tuberculosis, human immunodeficiency virus

Early obstetric complicating factors:

• Alcohol/illicit drug exposure in pregnancy

• Multiple pregnancy

• Previous preterm birth

• Previous stillbirth

• Gestational hypertension/pre-eclampsia/eclampsia

• Gestational diabetes

• Fetal anomaly

• Intrauterine fetal death (> 20 + 0 weeks gestation or > 500 g at birth)

• Small-for-gestational age (birthweight <10th centile)

• Intrauterine growth restriction (birthweight <3rd centile)

• Large-for-gestational age (birthweight >90th centile)

• Placental abruption

• Persistent and unexplained antepartum vaginal bleeding

• Preterm birth

• Premature rupture of membranes