The birth outcomes of the 20 248 eligible pregnancies are detailed in Table 1; this information is based on ALSPAC recruitment records and maternity, birth and child health records. The full extent of miscarriage (foetal loss prior to 20 weeks of gestation) is likely to be under-represented in both the 1990–92 ALSPAC recruitment records and the records used to identify the eligible sample. Of the 20 390 known foetuses, the birth outcomes include 19 600 (96.1%) live births, 685 (3.4%) miscarriages and 105 (0.5%) stillbirths (defined as foetal loss after 20 weeks of gestation and stillborn deliveries). There are an additional 116 pregnancies with no known birth outcome. The ‘Children of the 90s’ ‘enrolled sample’ consists of 14 775 (75.7% of the 19 600 eligible live births) live-born children from the 15 247 pregnancies (15 458 foetuses) where an individual, either the mother/primary caregiver or the child, has provided data. Of these enrolled participants, ALSPAC has collected data relating directly to 14 009 (71.5% of 19 600 eligible live births) children, through self-reported data from the child or data provided
