Weighting of risk factors for low birth weight: A linked routine data cohort study in Wales, UK

Background Globally 20 million children are born with a birth weight below 2,500 grams every year which is considered as a low birthweight (LBW) baby. This study investigates the contribution of modifiable risk factors to inform activities that reduce the rates of LBW in Wales. Method The cohort (N = 693,377) was comprised of children born between 1 st January 1998 and 31 st December 2018 in Wales. A multivariable logistic regression model and a predictive model using decision tree were used to investigate the associations between the risk factors and LBW. Results The study found that non-singleton children had the highest risk of LBW (adjusted odds ratio 21.74, 95% confidence interval (CI) 21.09 – 22.40), followed by pregnancy interval less than one year (2.92, 95% CI 2.70 – 3.15), maternal diabetes (2.03, 95% CI 1.81 – 2.28), maternal hospital admission for anaemia (1.26, 95% CI 1.16 – 1.36), depression (1.58, 95% CI 1.43 – 1.75), serious mental illness (1.46, 95% CI 1.04 – 2.05), anxiety (1.22, 95% CI 1.08 – 1.38) and use of anti-depressant medication during pregnancy (1.92, 95% CI 1.20 – 3.07). Additional maternal risk factors include smoking (1.80, 95% CI 1.76 – 1.84), alcohol-related hospital admission (1.60, 95% CI 1.30 – 1.97), substance misuse (1.35, 95% CI 1.29 – 1.41), living in areas of high deprivation, and evidence of domestic abuse. Conclusion This work suggests that to address LBW, measures need to focus on improving maternal health, addressing pre-term births, promoting awareness of sufficient pregnancy interval, ensuring adequate support and resources for mother’s mental health and wellbeing. What is already known on this topic Each year 6.9% of live births are identified as low birth weight (LBW) in the UK. LBW children are at risk of poor cognitive development, which is associated with developmental disabilities and poor academic achievement in later life. The progress to reduce the LBW prevalence in high income regions (including Europe) is not satisfactory to meet World Health Organisation (WHO) LBW target by 2025. What this study adds This work has built an e-cohort using data-linkage across multiple routinely collected administrative datasets to investigate the risk factors of LBW for the population of Wales. Non-singleton children had 22 times higher risk of LBW than singleton children. Findingss: uggested that the most important factors to address to reduce the risk of LBW are multiple births, underlying maternal physical (diabetes, anaemia) and mental health, maternal smoking, and substance use (alcohol/drugs), adequate pregnancy interval, higher deprivation, and domestic abuse during pregnancy. How this study might affect research, practice, or policy This finding suggests that to address the LBW, adequate support is needed to the mother and their family when they are planning for and during pregnancy. Multiagency (doctors, midwives, security department) can liaise between them and can take necessary mitigative action to reduce the prevalence of LBW.