Gestational age and hospital admissions during childhood, the TIGAR study: population-based, record linkage study in England

Objectives: To explore the association between gestation at birth and hospital admissions to age 10 years and how admission rates change throughout childhood. Design: We used a population-based record-linkage cohort study design. Birth registration, birth notification and Hospital Episode Statistics were linked using a deterministic algorithm. Setting: National Health Service (NHS) hospitals in England, UK Participants: All live, singleton births in NHS hospitals occurring in England January 2005 to December 2006 (n=1,018,136). Main outcome measures: The primary outcome was all inpatient hospital admissions from birth to age 10 years, death or study end (March 2015) and the secondary outcome was the main cause of admission, which was defined as the first International Classification of Disease-10 (ICD10) code within each hospital admission record. Results: 525,039 (52%) children experienced at least one hospital admission during the study period. Hospital admissions during childhood were strongly associated with gestational age at birth (<28, 28-29, 30-31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, and 42 weeks). Compared to children born full term (40 weeks’ gestation), those born extremely preterm (<28 weeks) had the highest rate of hospital admission throughout childhood (adjusted RR, aRR=4·29, 95%CI: 4·58 to 5·30). Even children born at 38 weeks had a higher rate of hospital admission throughout childhood (aRR=1·19, 95%CI: 1·16 to 1·22). However, the association between gestational age and hospital admission decreased with increasing age (interaction p<0·001). Children born