Inequalities in low birth weight: parental social class, area deprivation,and "lone mother" status

Objective-To describe the extent of socioeconomic inequalities in low birth weight. To assess the relative benefits of measuring socioeconomic status by individual occupation, socioeconomic deprivation status of area of resid ence, or both, for describing inequalities and targeting resources. Design-Analysis of birth registrations by registration status: joint compar ed with sole registrants ("lone mothers"), routinely recorded parental occu pation (father's for joint registrants), and census derived enumeration dis trict (ED) deprivation. Setting-England and Wales, 1986-92. Subjects-471 411 births with coded parental occupation (random 10% sample) and birth weight. Main outcome measures-Proportion of low birth weight (<2500 g) Results-34% of births to joint registrants in social classes IV and V, and 45% of births to sole registrants, were in the quintile of most deprived ED s. It was found that 6.8% of births were of low birth weight. Sole registra nts were at higher risk (9.3% overall) than joint registrants, across all d eprivation quintiles. For joint registrants, the socioeconomic risk gradien t was similar by social class or area deprivation, but a greater gradient f rom 4.7% to 8.7% was found with combined classification. Conclusions-Up to 30% of low birth weight can be seen as being associated w ith levels of socioeconomic deprivation below that of the most affluent gro up, as measured in this study. Caution is needed when targeting interventio ns to high risk groups when using single indicators. For example, the major ity of births to lone mothers and to joint registrants in social classes IV and V would be missed by targeting the most deprived quintile. There is a high degree of inequality in low birth weight according to social class, ar ea deprivation and lone mother status. When using routinely recorded birth and census data, all three factors are important to show the true extent of inequalities.