The impact of birthweight on the development of cerebral palsy: A population-based matched case-control study.

BACKGROUND:Cerebral palsy (CP) is a common cause of physical impairment in children, especially in newborns who are small for gestational age (SGA). AIMS:The aim of our study was to investigate the association between birth weight and the risk of developing CP, controlling for gestational age and plurality. STUDY DESIGN:This retrospective, observational, case-control study was based on Slovenian Registry of Cerebral Palsy (SRCP) and Slovenian National Perinatal Information System (NPIS) data for the period 2002 to 2010. SUBJECTS:For each pregnancy that resulted in the birth of the newborn(s) who later developed CP (n = 254), three pregnancies with newborns who did not develop CP (n = 762) were selected and matched for gestational age and plurality. OUTCOME MEASURES:Diagnosis of CP was made at age 5 years or older by a developmental pediatrician trained in child neurology or a child neurologist using standard measures. RESULTS:Risk of CP increased progressively as birth weight percentiles fell below the 50th centile, with children in the lowest percentiles at greatest risk. Birth weight percentiles traditionally classified as SGA were an independent risk factor for developing CP, with an odds ratio of 2.43 (95% confidence interval 1.57, 3.73). CONCLUSIONS:The results of this study suggest that the risk for developing CP is inversely related to birth weight, even at birth weights that do not meet the standard definitions of SGA. SYNOPSIS - STUDY QUESTION:Does birth weight represent a potential risk factor for the development of cerebral palsy (CP) when controlling for gestational age and plurality? WHAT'S ALREADY KNOWN:Newborns who are small for gestational age (SGA) are at higher risk of developing CP according to published studies. However, different definitions of SGA (birth weight below the 10th, 5th, or 3rd percentile for gestational age) have been used by researchers and clinicians, making it difficult to compare studies. WHAT THIS STUDY ADDS:This study suggests that the risk of developing CP is inversely related to birth weight, even at birth weights that do not meet standard definitions of SGA.