Induction of labor and cerebral palsy: a population-based study in Norway.

To investigate the association between labor induction and later development of cerebral palsy (CP).Registry-based cohort study.Perinatal data on all children born in Norway 1996-1998 were obtained from the Medical Birth Registry of Norway (MBRN). Neurodevelopmental data were collected from the Norwegian Cerebral Palsy Registry (CPRN).A total of 176,591 children surviving the neonatal period. Of 373 children with CP, detailed data were available on 241.Unadjusted and adjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated as estimates of the relative risk that a child with CP was born after labor induction.Total CP and spastic CP subtypes.Bilateral cerebral palsy was more frequently observed after induced labor (OR: 3.1; 95% CI 2.1-4.5). For children born at term the association between bilateral CP and labor induction was stronger (OR: 4.4; 95% CI 2.3-8.6). The association persisted after adjustment for maternal disease, gestational age, standard deviation score for birthweight (z-score) and prelabor rupture of membranes (PROM) (adjusted OR: 3.7; 95%CI 1.8-7.5). Among children with CP born at term, four-limb involvement (quadriplegia) was significantly more frequent after induced (45.5%) compared with non-induced labor (8.0%). There was no significant association between labor induction and unilateral CP subtype or CP in preterm born children.In this study population, we found that labor induction at term was associated with excess risk of bilateral spastic CP and in particular CP with four-limb involvement.