Table 1

Population, birth numbers and data sources by study area

Maternal and pregnancy factorsAlberta, CanadaNew South Wales, AustraliaWestern Australia, AustraliaDenmarkNorwayScotlandSwedenMassachusetts, USA
Total population3.7 million7.0 million2.2 million5.5 million4.9 million5.1 million9.2 million6.5 million
Births per annum∼42 000∼90 000∼25 000∼66 000∼60 000∼58 000∼100 000∼80 000
Inclusion criteriaLive and stillbirths ≥20 weeksLive and stillbirths ≥20 weeks or ≥400 gLive and stillbirths ≥20 weeks or ≥400 gLive and stillbirths ≥22 weeksLive and stillbirths ≥22 weeks or ≥500 gLive and stillbirthsLive births ≥22 weeks; stillbirths ≥28 weeksLive and stillbirths >20 weeks or >350 g
Source of population dataDAD (H), BRVS (B)APDC (H), MDC (B)HMDS (H), MNS (B)DNRP, DMBRMBRNSMR02SMBRPELL
Linkage methodNAProbabilisticProbabilisticDeterministicNANANAProbabilistic
Source of hypertension dataHB and/or HB and/or HHBBBB 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 versionICD-10ICD-10ICD-10ICD-10ICD-10ICD-10ICD-10ICD-9
ICD codes for hypertension
 Pregnancy hypertensionO11, O13–16O11, O13–16O11, O13–16O11, O13–15O11, O13–15O11, O13–16O11, O13–16642.3–642.9
 Pre-eclampsiaO11, O14–15O11, O14–15O11, O14–15O11, O14–15O11, O14–15O11, O14–15O11, O14–15642.4–642.6
  • 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.