Characteristics of the cohorts contributing to the HELIX cohort
| Cohort | Recruitment in original cohort | Exclusions made during recruitment | Years of birth | Region covered by HELIX | No. of births in HELIX entire cohort |
| BiB, UK5 | All pregnant women who attended the oral glucose tolerance test clinic at Bradford Royal Infirmary in weeks 26–28 of pregnancy. | Women who planned to move away from Bradford before birth were excluded. | 2007–2010 | Bradford | 10 849 |
| EDEN, France6 | Pregnant women who attended prenatal care at the University hospitals of Nancy and Poitiers recruited before 24 weeks of amenorrhoea. | Twin pregnancies, women with known diabetes before pregnancy, insufficient French language skills and intention to move away from the recruitment area were excluded. | 2003–2006 | Nancy and Poitiers, urban areas | 1900 |
| INMA, Spain7 | Pregnant women who attended a prenatal care centre in the study region during weeks 6–10 of pregnancy. | Women who resided or intended to deliver outside the study area, who were aged under 16 years, who had twin or multiple pregnancies, who had assisted reproduction or who had communication problems were excluded. | 2003–2008 | Gipuzkoa Sabadell Valencia | 2063 |
| KANC, Lithuania8 | Pregnant women who attended one of four prenatal care clinics affiliated to the hospitals of the Kaunas University of Medicine during first trimester of pregnancy. | Women who lived outside Kaunas municipality, had medical records of pregnancy induced hypertension and/or diabetes were excluded. | 2007–2008 | Kaunas | 4107 |
| MoBa, Norway9 | Recruitment at the first ultrasound (US) scan, ie, during the 17–18 weeks of gestation. All women who gave singleton births in the participating maternity units. | None | 1999–2008 | Oslo | 11 095 |
| RHEA, Greece10 | Pregnant women who attended US examination before 15 week of pregnancy with residence in and near Heraklion at Crete. | Women who were aged under 16 years or who had communication problems were excluded. | 2007–2008 | Heraklion | 1458 |
| Total | 31 472 |
BiB, Born in Bradford; EDEN, Étude des Déterminants pré et postnatals du développement et de la santé de l’Enfant; INMA, INfancia y Medio Ambiente; KANC, Kaunus cohort; MoBa, Norwegian Mother and Child Cohort Study.