Objective: The objective of this study was to measure the agreement between hospital records and maternal reporting of mode of delivery in a representative UK sample.
Design: Population-based survey (Millennium Cohort Study).
Setting: UK.
Population: A total of 12,391 singleton infants born in 2000-2002.
Methods: Mothers were interviewed when infants were approximately 9 months old. Information was collected by interview on many obstetric and perinatal factors including mode of delivery. Record linkage to the mother's delivery hospital records was undertaken in those who gave consent (90%). A matching record was found for 83%. Maternal report and hospital records were compared using mode of delivery classified into three (normal, assisted and caesarean) and six groups. Factors associated with disagreement between the two data sources were identified.
Main outcome measure: Proportion of records in which there was agreement between the two data sources.
Results: Agreement between maternal report and hospital records was at least 94% using six mode of delivery groups and 98% using three groups. Much of the disagreement (57-63%, depending on country) was between forceps and ventouse, and between planned and emergency caesarean. Disagreement was more common in women whose babies were first born and in women not born in the UK.
Conclusion: Our study confirms that maternal reporting of mode of delivery is highly reliable. This is important for clinical staff caring for women and those conducting epidemiological studies. Additional data sources may be necessary to gather reliable data from ethnic minority women, particularly those born outside the UK, or to distinguish forceps from ventouse, or planned from emergency caesarean section.