Birth Data Linkage Project - Stage 1
This page describes the first stage of the City University Birth Data Linkage Project.
Stage 1: Linkage of birth registration data with the NHS Numbers for Babies (NN4B) dataset
Hilder L, Moser K, Dattani N and Macfarlane A (2007). Pilot linkage of NHS Numbers for Babies data with birth registrations. Health Statistics Quarterly 2007; 33: 25-33 External link: http://www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--33--spring-2007/pilot-linkage-of-nhs-numbers-for-babies.pdf
- This pilot study showed that it was possible to link almost all NN4B records with a birth registration record, paving the way for further analyses.
Moser K, Macfarlane A, Chow YH, Hilder L, Dattani N (2007). Introducing new data on gestation-specific infant mortality among babies born in 2005 in England and Wales. Health Statistics Quarterly 2007; 35: 13-27. http://www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--35--autumn-2007/introducing-new-data-on-gestation-specific-infant-mortality-among-babies-born-in-2005-in-england-and-wales.pdf
Supplementary data http://www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--35--autumn-2007/health-statistics-quarterly-supplementary-data.pdf
- As a result of the linkage between birth registration data and NN4B data, this paper presented new data on infant mortality by gestational age, including in relation to birthweight, multiplicity, age of mother, marital status/registration type, and the National Statistics Socio-Economic Classification. Key findings (% rounded to nearest whole number) were:
- Gestational age is known for 99% of live births in 2005.
- In 2005 8% of live births were preterm (under 37 weeks gestational age); 88% were born at term (37 to 41 weeks); and 4% were born post term (42 weeks and above). The corresponding infant mortality rates were 42, 1.8, and 2.0 deaths per 1,000 live births respectively.
- Infant mortality was highest at the very low gestational ages; 947 deaths per 1,000 live births among babies born at 22 weeks. It then decreased with gestational age to 1.3 deaths per 1,000 live births among babies born at 40 weeks gestation.
- Infant mortality varied considerably among term births. The infant mortality rate of babies born at 37 weeks was over three times that of babies born at 40 weeks.
- Among babies born at 37 weeks and above, the neonatal mortality rate of those weighing 1,500–2,499g at birth was 5.3 deaths per 1,000 live births as compared to 0.8 deaths per 1,000 live births for those weighing 2,500g and over.
- For babies born at 37 weeks and above, the postneonatal mortality among babies with fathers in routine and manual occupations was almost twice that of babies whose fathers had managerial and professional occupations.
Moser K and Hilder L (2008). Assessing quality of NHS Numbers for Babies data and providing gestational age statistics. Health Statistics Quarterly 2008; 37: 15–23. http://www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--37--spring-2008/quality-of-nhs-numbers-for-babies-data-and-providing-gestational-age-statistics.pdf
- This paper assessed the quality of NN4B data, in particular the completeness of plausibility of gestational age and birthweight combinations. Key findings were:
- NHS Numbers for Babies (NN4B) data are generally of good quality
- The gestational age data are credible, consistent with other data sources, and the statistics by maternal age, multiplicity and sex are as expected
- The percentage of singleton live births born preterm is lowest in babies of mothers aged 30-34 as compared to all other maternal age groups
- The gestational age statistics, previously unavailable for England and Wales as a whole, provide a reference against which to monitor trends in preterm births, and can inform the provision of neonatal care
- The NN4B dataset is a powerful new source which can extend what is known about births in England and Wales
Moser K, Stanfield KM and Leon DA (2008). Birthweight and gestational age by ethnic group, England and Wales 2005: introducing new data on births. Health Statistics Quarterly 2008; 39: 22-31 http://www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--39--autumn-2008/birthweight-and-gestational-age-by-ethnic-group--england-and-wales-2005.pdf
- This paper presented the first data on ethnic differences in birthweight and gestational age for births in England and Wales as a whole. Key findings (% rounded to nearest whole) were:
- Ethnic group was recorded for 89% of births in England and Wales in 2005. Of the total, 64% were recorded as
White British, 9% as Asian/Asian British (Bangladeshi 1%, Indian 3%, Pakistani 4%) and 5% as Black/Black British (African 3%, Caribbean 1%)
- The percentage of low birthweight live singleton births in the Caribbean group and all three Asian groups was almost twice that in the White groups; it ranged from 6% in the White British group to 11% in the Caribbean group
- Live singleton births recorded as Indian or Bangladeshi weighed 300 grams less on average than those recorded as White. A similar birthweight difference was seen among those born at 40 weeks gestational age
- The percentage of live singletons born preterm varied from 10% in the Caribbean group to 6% in the White British
group and 6% in the Bangladeshi group
- There was a five-fold difference across ethnic groups in the percentage of babies born to mothers under age 20. It was 2% in the Indian group, 8% in the White British group and 10% in the Caribbean group
Oakley L, Maconochie N, Doyle P, Dattani N, Moser K (2009). Multivariate analysis of infant death in England and Wales in 2005-06, with focus on socio-economic status and deprivation. Health Statistics Quarterly 2009; 42: 22-39 http://www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--42--summer-2009/multivariate-analysis-of-infant-death-in-england-and-wales-in-2005-06--with-focus-on-socio-economic-status-and-deprivation.pdf
- This article investigated the risk factors for infant mortality in England and Wales in 2005–06, focusing on the contribution of socio-economic status and deprivation. Key findings were:
- Among all singleton live births in England and Wales, 2005–06, as levels of deprivation increased, mothers tended to be younger, less likely to be married or living with the father, and more likely to be non-UK-born
- Babies who were Asian, Black or of other non-white ethnicity tended to have higher levels of deprivation
- Preterm birth, low birthweight and small-for-gestational-age increased in prevalence with increasing levels of deprivation
- Deprivation, births outside marriage, non-white ethnicity of infant, maternal age under the age of 20 and male sex were all
independently associated with an increased risk of infant mortality
- Lower birthweight, earlier gestation and small-for-gestational-age were strongly associated with infant mortality, with the effect of birthweight and gestation most marked in the neonatal period
- The effect of deprivation on death in the first year of life was partly confounded by maternal age, registration status/marital
type and ethnicity of baby, but a trend of increasing risk of death with increasing deprivation persisted after adjustment. One
quarter of all deaths under one year would potentially be avoided if all births were to women with the lowest level of deprivation
- Trends of increasing mortality risk with increasing deprivation tended to be strongest in the postneonatal period
- Statistically significant interactions were found between deprivation and low birthweight, preterm and small-forgestational-
age. There was a stronger association between deprivation and infant mortality among babies who were not low birthweight, and among non-small-for-gestational-age babies. With regard to gestation, the strongest effect of deprivation was observed among preterm births in the neonatal period, and among term births in the postneonatal period
- Around 28 per cent of postneonatal deaths (45 per year) among non-low birthweight babies, and 24 per cent of postneonatal deaths (131 per year) among babies born at term, would potentially be avoided if all levels of deprivation were reduced to that of the least deprived group
- The National Statistics Socio-economic Classification showed similar associations with infant mortality to deprivation, but small numbers prohibited the calculation of fully adjusted models using this factor
Moser K (2009). Gestation-specific infant mortality by social and biological factors among babies born in England and Wales in 2006 Health Statistics Quarterly 2009; 42: 78-87 http://www.ons.gov.uk/ons/rel/child-health/gestation-specific-infant-mortality-in-england-and-wales/2006/2006-report-pdf-download.pdf
- This report follows on from earlier papers reporting on gestation-specific infant mortality, now analysing births in 2006. Key findings for 2006 were:
- In 2006 8% of live births were preterm (under 37 weeks gestational age), 88% were born at term (37 to 41 weeks), and 4% were born post term (42 weeks and above). The corresponding infant mortality rates were 41.0, 1.9, and 1.5 deaths
per 1,000 live births respectively
- Among babies born at 37 weeks and above, the neonatal mortality rate of those weighing 1,500–2,499 grams at birth was 4.3 deaths per 1,000 live births as compared with 0.7 deaths per 1,000 live births among those weighing 2,500 grams and over
- Over half (53%) of multiple births were born preterm as compared with only 6% of singleton births
- The infant mortality rate of babies born at term/post term to mothers under age 20 was almost twice that of term/post term babies born
to mothers aged 30–34 (2.7 deaths per 1,000 live births compared with 1.4 deaths per 1,000 live births)
- The percentage of babies born preterm varied by marital status/registration type from 7.0 per cent among babies born inside marriage to 9.7 per cent among sole registrations
- Among babies born at 37 weeks and over, neonatal and total infant mortality in the routine and manual group was almost twice that in
the managerial and professional group
- Infant mortality rates in the Pakistani and Caribbean groups were over twice the infant mortality of the White British group (9.8 deaths per 1,000 live births compared with 4.4 deaths per 1,000 live births)
Messer J (2011) An analysis of the socio-demographic characteristics of sole registered births and infant deaths. Health Statistics Quarterly 2011; 50: 1-23
- As a result of the linkage project between birth registration and NN4B data for 2005 and 2006, ONS were able to continue linking these data sources for subsequent years. This paper describes work done analysing births in 2007 and 2008 and further linkage with death registration records.
- This study reported differences in levels of deprivation and baby outcomes between couples living together (whether married or not), parents living separately, and sole registrations, with the stillbirth rate highest in the sole registration group.
Stage 2 publications