The contribution of gestational age, area deprivation and mother’s country of birth to ethnic variations in infant mortality in England and Wales: A national cohort study using routinely collected data

Abstract

ObjectivesWe aimed to describe ethnic variations in infant mortality and explore the contribution of area deprivation, mother’s country of birth, and prematurity to these variations.MethodsWe analyzed routine birth and death data on singleton live births (gestational age≥22 weeks) in England and Wales, 2006–2012. Infant mortality by ethnic group was analyzed using logistic regression with adjustment for sociodemographic characteristics and gestational age.ResultsIn the 4,634,932 births analyzed, crude infant mortality rates were higher in Pakistani, Black Caribbean, Black African, and Bangladeshi infants (6.92, 6.00, 5.17 and 4.40 per 1,000 live births, respectively vs. 2.87 in White British infants). Adjustment for maternal sociodemographic characteristics changed the results little. Further adjustment for gestational age strongly attenuated the risk in Black Caribbean (OR 1.02, 95% CI 0.89–1.17) and Black African infants (1.17, 1.06–1.29) but not in Pakistani (2.32, 2.15–2.50), Bangladeshi (1.47, 1.28–1.69), and Indian infants (1.24, 1.11–1.38). Ethnic variations in infant mortality differed significantly between term and preterm infants. At term, South Asian groups had higher risks which cannot be explained by sociodemographic characteristics. In preterm infants, adjustment for degree of prematurity (<28, 28–31, 32–33, 34–36 weeks) fully explained increased risks in Black but not Pakistani and Bangladeshi infants. Sensitivity analyses with further adjustment for small for gestational age, or excluding deaths due to congenital anomalies did not fully explain the excess risk in South Asian groups.ConclusionsHigher infant mortality in South Asian and Black infants does not appear to be explained by sociodemographic characteristics. Higher proportions of very premature infants appear to explain increased risks in Black infants but not in South Asian groups. Strategies targeting the prevention and management of preterm birth in Black groups and suboptimal birthweight and modifiable risk factors for congenital anomalies in South Asian groups might help reduce ethnic inequalities in infant mortality.

Ethnic differences in singleton preterm birth in England and Wales, 2006‐12: Analysis of national routinely collected data

“…All Mixed groups and ‘Other’ groups were aggregated because of small numbers and the complexity of the heterogeneous composition of the subgroups which would have made any results difficult to interpret. Details of the derivation of the ethnic group categories are reported elsewhere …”

“…This has shown that compared with White mothers, the risks of preterm birth are consistently higher for Black mothers but similar or lower for East Asian and Hispanic mothers . Health disparities between ethnic groups have also been observed in England and Wales . In particular, the risk of preterm birth, especially very preterm birth, is high among mothers of Caribbean and West African origin compared with White mothers .…”

Ethnic and socioeconomic variation in cause-specific preterm infant mortality by gestational age at birth: national cohort study

“…After exclusions for implausible gestational age (0.4%), missing birth weight (0.4%) and implausible birth weight (1.5%), there were 4 634 932 live singleton births,16 of which 256 142 were at 24–36 completed weeks of gestation (table 1). The proportion of births in the ‘unstated’ category of ethnicity was 6%, decreasing from 10% in 2006 to 4% in 2012.…”

“…We conducted a national cohort study using routine data provided by the Office for National Statistics (ONS), based on National Health Service birth notifications linked with civil birth and death registrations. Details are reported elsewhere 16. The full cohort comprised all 4.7 million singleton babies born alive at 22+ completed weeks of gestation in England and Wales from 1 January 2006 to 31 December 2012.…”

“…Following WHO guidelines,19 we categorised gestational age at birth as 24–27 completed weeks (extremely preterm), 28–31 (very preterm) and 32–36 (moderate/late preterm). We grouped the baby’s ethnicity (stated by the mother) as White British, White Non-British, Pakistani, Indian, Bangladeshi, Black African, Black Caribbean, other stated and unstated16; the ‘other stated’ group included categories that were mixed (eg, mixed White and Black Caribbean), rare (eg, Chinese) or non-specific (eg, ‘any other Asian background’). We assessed socioeconomic disadvantage using quintile categories of the respective national Index of Multiple Deprivation (IMD) for England 201520 and for Wales 2014,21 based on the mother’s address at birth registration.…”