Birth weight trends in England and Wales (1986–2012): babies are getting heavier

Abstract

IntroductionBirth weight is a strong predictor of infant mortality, morbidity and later disease risk. Previous work from the 1980s indicated a shift in the UK towards heavier births; this descriptive analysis looks at more recent trends.MethodsOffice for National Statistics (ONS) registration data on 17.2 million live, single births from 1986 to 2012 were investigated for temporal trends in mean birth weight, potential years of birth weight change and changes in the proportions of very low (<1500 g), low (<2500 g) and high (≥4000 g) birth weight. Analysis used multiple linear and logistic regression adjusted for maternal age, marital status, area-level deprivation and ethnicity. Additional analyses used the ONS NHS Numbers for Babies data set for 2006–2012, which has information on individual ethnicity and gestational age.ResultsOver 27 years there was an increase in birth weight of 43 g (95% CI 42 to 44) in females and 44 g (95% CI 43 to 45) in males, driven by birth weight increases between 1986–1990 and 2007–2012. There was a concurrent decreased risk of having low birth weight but an 8% increased risk in males and 10% increased risk in females of having high birth weight. For 2006–2012 the birth weight increase was greater in preterm as compared with term births.ConclusionsSince 1986 the birth weight distribution of live, single births in England and Wales has shifted towards heavier births, partly explained by increases in maternal age and non-white ethnicity, as well as changes in deprivation levels. Other potential influences include increases in maternal obesity and reductions in smoking prevalence particularly following the introduction of legislation restricting smoking in public places in 2007.

Increasing obstetric intervention for fetal growth restriction is shifting birthweight centiles: a retrospective cohort study

“…The three most recently published Australian birthweight centile charts, for births in 1991–94, 1998–2007 and 2004–2013, 11,15,16 have shown an increase in the birthweights defining each centile. Similar trends have been reported elsewhere 18‐21 . This has been attributed to changing maternal influences on birthweight such as falling rates of smoking and increasing rates of maternal obesity and gestational diabetes 18,22‐24 .…”

Birth weight centiles and small for gestational age by sex and ethnicity for England and Wales

“…Our sex-specific centiles using the UK-EBWC data for 2006–2012 for all live singleton births were similar matching to those published from the MBRRACE group (data not shown),25 who also used data from NN4B (but for 2013–2014) plus stillbirths alive at onset of labour (n=1 269 403). Both MBRRACE and our study centiles showed higher birth weights than those reported in 2009 UK-WHO charts5, in line with observed increased birth weight trends between 2006 and 2012 as reported in Ghosh 26. The UK-WHO revised charts computed on 9443 births, mostly from East of England,5 were limited and not representative.…”

“…Finally, given that birth weight trends are known to change over time,26 we recommend that such analyses are updated periodically.…”

Pregnancy outcome of Japanese patients with glucokinase–maturity‐onset diabetes of the young

“…Currently, the reported average birthweight of Japanese neonates is 3,050 g for males and 2,960 g for females, as opposed to 3.436 g for males and 3,316 g for females in the UK. The birthweight difference in the current study is likely to reflect this racial difference in birthweight.…”