P erinatal asphyxia, a major cause of neonatal and childhood death and morbidity (eg, hypoxic ischemic encephalopathy, seizures, intraventricular hemorrhage, cerebral palsy, and delayed development), is predicted by fetal acidosis measured by umbilical cord pH at birth. The cord pH (about <7.00) and base deficit (about Z12 mmol/L) levels commonly used to judge risk, were derived by consensus, and the longterm implications of a low arterial cord pH are uncertain. Despite this, cord pH values are commonly used as an outcome measure in obstetric clinical trials, are a benchmark for judging obstetricians' clinical performance, and are used to support medicolegal claims of harm due to intrapartum events that might lead to long-term child disability. The authors of this systematic review and meta-analysis evaluated more closely the association between umbilical cord pH readings at birth and short-term and long-term childhood outcomes.Data were obtained from Medline, Embase, the Cochrane Library (2008 issue 8), and Medion, without language restrictions. Reference lists of selected articles were recorded, follow-up contact with authors was performed and review articles, the SIGLE, Web of Science, the national research register, and medical conferences register were all examined. Eligible studies were those (cohort, case-controlled, review) in which cord pH at birth was compared with any neonatal or long-term outcome. Criteria for inclusion also included a study population of >5 subjects in whom cord blood was obtained at birth, performance of an index test (cord blood examined for arterial or venous pH or base excess); a recording of outcomes (any measure of compromise of neonatal or childhood well-being); and inclusion of a study design that allowed generation of a 2 Â 2 table to compute estimates of associations between test results and outcomes. The primary outcome measures were neonatal mortality, an author created composite of neonatal morbidity, and cerebral palsy.A total of 51 primary articles (with 481,753 infants) were found, with widely variable design, quality, outcome definition, and results. Meta-analyses carried out within predefined groups from 43 studies showed that low arterial cord pH was significantly associated with neonatal mortality [odds ratio (OR), 16.9; 95% confidence interval (CI), 9.7-29.5]; hypoxic ischemic encephalopathy (OR, 13.8; 95% CI, 6.6-28.9); intraventricular hemorrhage or periventricular leukomalacia (OR, 2.9; 95% CI, 2.1-4.1); and cerebral palsy (OR, 2.3; 95% CI, 1.3-4.2). Longterm (1 to 8 y) adverse outcomes found in 15 studies included cerebral palsy, unspecified neurologic abnormalities, intelligent quotient (IQ) deficits, and developmental problems.
