An analysis of the socio-demographic characteristics of sole registered births and infant deaths.

BACKGROUND Differences in birth characteristics and infant mortality rates by marital status and birth registration type reflect complex underlying factors. In particular, births registered solely by the mother are seen as a disadvantaged group. This article analyses the socio-demographic characteristics of births by registration type and parents' marital status and explores these differences for health outcomes. METHODS Birth notifications data from the NHS Numbers for Babies system was linked to birth registration data held by the Office for National Statistics (ONS) for births occurring in 2007 and 2008 in England and Wales. This dataset was further linked to death registration data to identify infants who died before their first birthday.Regression analysis was used to compare factors and health outcomes across marital and registration status groups. Regression models were calculated to determine the main risk factors for poor outcomes. RESULTS The registration groups differed in the age of the mother at birth, the proportion of young mothers, ethnic group distribution and measures of deprived circumstances. The joint registered-different address and sole registered groups were similar in the proportion of young mothers and the deprivation indices. The groups also differed in the proportion of low birthweight and premature babies. The joint registered-different address and sole registered groups both had higher percentages of 'small for gestational age' babies compared with the within-marriage and joint registered-same address groups. The stillbirth rate was highest in the sole registered group. Both the joint registered-different address and sole registered groups had higher infant mortality rates compared with the within-marriage and joint registered-same address groups. Multivariate analysis indicated that low birthweight was a key factor in infant mortality. CONCLUSIONS Births registered solely by the mother were found to be a disadvantaged group but were also similar to the joint-registered group living at different addresses in their main socio-demographic characteristics and health outcomes. The joint-registered group living at the same address was similar to the within-marriage group across the same measures. This argues that, in the 21st century, the distinction between infants with 'resident' and 'nonresident' fathers is more meaningful for health outcomes than that between births inside and outside marriage.