Early Human Development, 5 (1981) 167-178 Elsevier/North-Holland Biomedical Press 167 SPASTIC CEREBRAL PALSY: CHANGES IN BIRTHWEIGHT AND GESTATIONAL AGE FIONA J. STANLEY N.H. and M.R.C. Research Unit in Epidemiology and Preventive Medicine, University Department of Medicine, Queen Elizabeth II Medical Centre, Nedlands, Western Austmlia 6009, Australia Accepted for publication 3 December 1980 SUMMARY The birthweight and gestational age frequency distributions for spastic cerebral palsy (CP) cases and their controls were obtained from the Western Australian CP register. Following the introduction of neonatal intensive care, spastic CP rates have fallen amongst heavier (22500 g) infants and remained steady or risen amongst low birthweight (LBW: <2500 g) infants. The expected bimodality of both the birthweight and gestational age distributions for spastic diplegia cases was obvious in these data. Marked peaks occurred at 1500 g and 31 weeks and 3000 g and 39 weeks. The num- bers of heavier, term diplegics fell between 1961-1965 and 1971-1975, and thus there were proportionally more preterm LBW diplegics more recently. The reasons for the fall in the heavier diplegics need investigation. Spastic hemiplegic and quadriplegic cases were more like the controls but with distributions skewed to the left. More of these individuals were more recently small for gestational age (SGA: <2500 g and over 37 weeks gesta- tion). This highlights the importance of intrauterine damage in these two groups of spastic CP individuals. cerebral palsy; birthweight; gestational age; neonatal care; trends INTRODUCTION It has been known for nearly a century that low birthweight and preterm birth were risk factors for certain cerebral palsy syndromes [ 111, particularly spastic diplegia [ 1,161. Correspondence and reprint requests to: Dr. F.J. Stanley, N.H. and M.R.C. Research Unit in Epidemiology and Preventive Medicine, University Department of M edicine, Queen Elizabeth II Medical Centre, Nedlands, Western Australia 6009. 037% 3782/81/0000-0000/$02.50 @ Elsevier/North-Holland Biomedical Press