Modifiable risk factors for low birth weight and their effect on cerebral palsy and mental retardation

Objective: to estimate the effect of modifiable risk factors on low birth weight and two of its sequelae-cerebral palsy and mental retardation. Methods: The population attributable risk percent (PARP) was used as a measure of effect. A literature search was conducted to determine estimates of the percent of CP and MR attributable to low birth weight. Data from the 19961997 Georgia Pregnancy Risk Assessment Monitoring System (PRAMS), a population based surveillance system, were used to estimate the percent of low birth weight attributable to modifiable risk factors. The PARP was calculated for smoking and unwanted conception. Results: Unwanted pregnancy and smoking were statistically significant risk factors for LBW. Four percent of all LBW births were attributable to unwanted pregnancy. If all unwanted pregnancies were prevented, 13% of cases of CP (27 cases per year in GA) and 14% of cases of MR (151 cases per year in GA) would be prevented. In wanted or mistimed pregnancies, 6% of LBW births were attributable to smoking. If all smoking during wanted or mistimed pregnancy was prevented, an additional 2.5% (5 cases) of CP and an additional 0.8% (8 cases) of MR would be prevented in Georgia each year. If all unwanted pregnancies and all smoking during wanted or mistimed pregnancies were prevented, 1692 LBW births could be prevented per year and the rate of LBW in Georgia would fall from 7.6% to 6.8%. Additionally, 32 cases of cerebral palsy and 159 cases of mental retardation could be prevented each year in Georgia. Conclusions: The PARP approach is useful in estimating the benefit of evidence-based prevention services. Preventing unwanted pregnancy and smoking during pregnancy would substantially reduce the burden of cerebral palsy and mental retardation in Georgia.