“…These variables are congenital malformations (21,(34)(35)(36), multiple pregnancy (37)(38)(39), unhealthy placenta and placenta previa (21,4041), abnormal amniotic fluid (19,21), prematurity (6,8,18,42), low birthweight for gestational age (7,8,10,11,24,42), large head circumference at birth ( 11,28,43) and forceps delivery (8). Birth trauma and birth asphyxia have also been reported as determinants of CP, but there is no agreement about their quantitative importance (4,5,8,20,21,26,(44)(45)(46)(47)(48)(49). Moreover, it cannot be documented with certainty in case-control studies whether statistical associations between either of these variables and CP reflect disease causation, uncontrollable information bias or consequences of the disease.…”