Population, birth numbers and data sources by study area
| Maternal and pregnancy factors | Alberta, Canada | New South Wales, Australia | Western Australia, Australia | Denmark | Norway | Scotland | Sweden | Massachusetts, USA |
| Total population | 3.7 million | 7.0 million | 2.2 million | 5.5 million | 4.9 million | 5.1 million | 9.2 million | 6.5 million |
| Births per annum | ∼42 000 | ∼90 000 | ∼25 000 | ∼66 000 | ∼60 000 | ∼58 000 | ∼100 000 | ∼80 000 |
| Inclusion criteria | Live and stillbirths ≥20 weeks | Live and stillbirths ≥20 weeks or ≥400 g | Live and stillbirths ≥20 weeks or ≥400 g | Live and stillbirths ≥22 weeks | Live and stillbirths ≥22 weeks or ≥500 g | Live and stillbirths | Live births ≥22 weeks; stillbirths ≥28 weeks | Live and stillbirths >20 weeks or >350 g |
| Source of population data | DAD (H), BRVS (B) | APDC (H), MDC (B) | HMDS (H), MNS (B) | DNRP, DMBR | MBRN | SMR02 | SMBR | PELL |
| Linkage method | NA | Probabilistic | Probabilistic | Deterministic | NA | NA | NA | Probabilistic |
| Source of hypertension data | H | B and/or H | B and/or H | H | B | B | B | B and/or H |
| No of diagnosis fields for hypertension reporting (data source) | 25 (H) | 11 (H) Checkbox (B) | 21 (H) Checkbox (B) | 20 (H) | Check-boxes and free text (B) | 6 (B) | 12 (B) | 15 (H) Check-box (B) |
| ICD version | ICD-10 | ICD-10 | ICD-10 | ICD-10 | ICD-10 | ICD-10 | ICD-10 | ICD-9 |
| ICD codes for hypertension | ||||||||
| Pregnancy hypertension | O11, O13–16 | O11, O13–16 | O11, O13–16 | O11, O13–15 | O11, O13–15 | O11, O13–16 | O11, O13–16 | 642.3–642.9 |
| Pre-eclampsia | O11, O14–15 | O11, O14–15 | O11, O14–15 | O11, O14–15 | O11, O14–15 | O11, O14–15 | O11, O14–15 | 642.4–642.6 |
APDC, Admitted Patient Data Collection; B, Birth or obstetric data; BRVS, Birth Registry of Vital Statistics; DAD, Discharge Abstract Database; DMBR, Danish Medical Birth Registry; DNRP, Danish National Registry of Patients; H, Hospital data; HMDS, Hospital Morbidity Data System; ICD, International Classification of Diseases; MBRN, Medical Birth Registry of Norway; MDC, Midwives Data Collection; MNS, Midwives' Notification System; NA, Not Applicable; PELL, Pregnancy to Early Life Longitudinal Data System; SMBR, Swedish Medical Birth Register; SMR02, Scottish Morbidity Record 2.