Cause-specific perinatal death rates, birth weight and deprivation in the West Midlands, 1991-93

Abstract

Objectives: To study the relationship between cause-specific perinatal death rates, material deprivation and birthweight among births in 3 consecutive years in the West Midlands Health Region.

Study design: Retrospective cohort study.

Setting: West Midlands Health Region (WMHR).

Study population: All births (live and stillbirths) to mothers with addresses in the WMHR in 1991, 1992 and 1993.

Main outcome measures: Cause-specific perinatal death rates--crude and stratified by birthweight.

Methods: Perinatal deaths in the WMHR in 1991-93, collected as part of the national Confidential Enquiry into Stillbirths and Deaths in Infancy, were classified into causes of death by the extended Wigglesworth classification. Crude rates for cause-specific perinatal deaths and rates stratified by birthweight < 2500 g and > or = 2500 g were calculated for each enumeration district (ED) quintile derived by ranking enumeration districts for the whole of the region by Townsend Deprivation Index. Cause-specific rates of death were investigated for a linear trend across ED quintiles. The relative risk of death (most vs least deprived) from specific causes was calculated. Using rates for the least deprived quintile as the reference, deaths from each cause 'attributable' to social inequality were calculated.

Results: Positive linear trends in perinatal deaths were noted with increasing deprivation for each specific cause of death except those classified as 'other causes' (Wigglesworth Class E). Relative risk (most vs least deprived) of perinatal death with a congenital anomaly was 1.98 (confidence interval, CI: 1.36,2.89). For deaths related to antepartum events, intrapartum events and immaturity the risks were 1.81 (CI: 1.39,2.38), 1.48 (CI: 1.10,1.98) and 1.92 (CI 1.45,2.56), respectively. Forty-three (35.7%) perinatal deaths per year were due to congenital anomalies, 63 (29.7%) antepartum events, 36 (21.9%) intrapartum events and 61 (32.7%) immaturity and these were statistically 'attributable' to social inequality. Cause-specific perinatal death rates for babies < 2500 g showed no correlation with deprivation; however, for babies > or = 2500 g the association with deprivation persisted.

Conclusions: All cause-specific rates except those due to 'other causes' showed a positive linear trend with increasing deprivation. These trends were found for infants born > or = 2500 g but were not seen for low birthweight infants (< 2500 g). Almost 30% of deaths were statistically 'attributable' to social inequality. The results of this study suggest that material deprivation plays an important role in the causal pathway leading to perinatal death and needs to be addressed in preventive programmes aimed at the reduction of perinatal deaths.