To compare the incidence of and risk factors for cerebral palsy (CP) in moderately preterm (MP) (32+0–33+6 weeks) and late preterm (LP) (34+0–36+6 weeks) infants with those in very preterm (VP) (<32+0 weeks) and term infants (≥37 weeks).
The national register study included all live-born infants in Finland from 1991 to 2008. Infants who died before the age of 1 year, had any major congenital anomaly, or had missing data were excluded. A total of 1 018 302 infants were included in the analysis and they were analyzed in 4 subgroups (VP, MP, LP, and term) and 3 time periods (1991–1995, 1996–2001, and 2002–2008).
By the age of 7 years, 2242 children with CP were diagnosed (0.2%). CP incidence was 8.7% in the VP, 2.4% in the MP, 0.6% in the LP, and 0.1% in the term group. The risk of CP was highest in the study period 1991–1995 in all groups. Factors predictive of an increased CP risk in the MP and LP groups included resuscitation at birth (odds ratio 1.60; 95% CI 1.01–2.53 and 1.78; 1.09–2.90), antibiotic treatment during the first hospitalization (1.63; 1.08–2.45 and 1.67; 1.13–2.44), 1-minute Apgar score <7 (1.70; 1.15–2.52 and 1.80; 1.21–2.67) and intracranial hemorrhage (7.18; 3.60–14.3 and 12.8; 5.58–29.2).
The incidence of CP is higher in LP and MP infants compared with term infants. There is a nonlinear decrease in incidence over time and with increasing gestational age.