Table 3.
Candidate predictors to be evaluated in model development: definition, variable type and units/ categories
| Candidate predictor | Definition | Variable type | Units/categories |
| Demographics | |||
| Age | Mother’s age | Continuous | years |
| Clinical history | |||
| Nulliparity | The condition in a woman of never having given birth | Binary | 0 ‘No’ 1 ‘Yes’ |
| Gestational age at diagnosis | Gestational age at diagnosis of GDM in the index pregnancy | Continuous | weeks’ gestation |
| Ethnicity | Self-reported ethnicity with classification aligned to the Australian Standard Classification of Cultural and Ethnic Groups57 | Categorical | Ethnicity classified into approximately five to six categories |
| Previous GDM | Previous diagnosis of GDM | Binary | 0 ‘No’; 1 ‘Yes’ |
| Previous LGA | Previous child with birthweight >90th percentile corrected for gestation and fetal sex using Australian population growth chart56 | Binary | 0 ‘No’ 1 ‘Yes’ |
| Previous pre-eclampsia or eclampsia | Pre-eclampsia or eclampsia in a previous pregnancy | Binary | 0 ‘No’ 1 ‘Yes’ |
| Previous shoulder dystocia | Shoulder dystocia in a previous pregnancy | Binary | 0 ‘No’ 1 ‘Yes’ |
| Family history of diabetes | Any family history of diabetes | Binary | 0 ‘No’ 1 ‘Yes’ |
| Height | The mother’s self-reported height at about the time of conception. | Continuous | centimetres (cm) |
| Body mass index | Body mass divided by the square of the body height | Continuous | kg/m2 |
| Weight | Mother’s self-reported weight (body mass) about the time of conception | Continuous | kilograms (kg) |
| Physical examination | |||
| Incremental gestational weight gain | Weight at first GDM clinic appointment (at around 30 weeks gestation) minus preconception weight divided by gestational weeks completed at the time of the first GDM clinical appointment | Continuous | kg |
| Laboratory investigations | |||
| Fasting glucose from diagnostic OGTT | Glucose level from baseline or time zero of diagnostic oral glucose tolerance test | Continuous | mmol/L |
| 1-hour glucose from diagnostic OGTT | Glucose level 1-hour following a 75 g oral glucose load of diagnostic oral glucose tolerance test | Continuous | mmol/L |
| 2-hour glucose from diagnostic OGTT | Glucose level 2-hour following a 75 g oral glucose load of diagnostic oral glucose tolerance test | Continuous | mmol/L |
BMI, body mass index; GDM, gestational diabetes; LGA, large-for-gestational-age; OGTT, oral glucose tolerance test.