Prevalence of maternal substance use during pregnancy and first two years of life: A whole-population cohort of 970,470 Australian children born 2008-2017

ObjectivesTo estimate the prevalence of maternal substance use during the first 1000 days of childrens lives, to inform planning and resourcing of antenatal screening and substance use in pregnancy services, alongside antenatal and postnatal health, parenting and social support services for pregnant women/new mothers and their babies. MethodThis whole-population cohort was assembled from birth registration, perinatal, and hospital data for children born 2008-2017, and their mothers, using data linked for the New South Wales (NSW) Child E-Cohort Project. The primary outcome was maternal substance use and treatment recorded in six health, death, and child protection data sources from the childs conception to age 2-years (the first 1000 days), including illicit substances, alcohol, opioid-agonist treatment, and misuse of psychoactive medicines or substances. ResultsOf 970,470 children born to 625,856 mothers, 3.4% (N=32,647) had [≥]1 maternal substance use records in the first 1000 days, including alcohol use (N=13,647; 1.4%) and other drug use (N=23,485; 2.4%). Maternal substance use was recorded during the pregnancy period for 1.2% of children, and from 28-1000 days post-birth for 2.4% of children. Outcome ascertainment was highest from child protection records (N=26,045), followed by mothers (N=12,956) then childrens hospital records (N=3,826). Child protection records more than doubled the prevalence from health and death records alone (1.4%). Social and health disadvantage was more common among children with maternal substance use. ConclusionDuring the first 1000 days of life, 3.4% of NSW children had [≥]1 maternal substance use record in health, child protection and death data sources. Child protection data enhances public health intelligence on the burden of maternal substance use among whole-populations of children. Near universal health system contact during pregnancy and birth is an opportunity to initiate early support for maternal substance use and co-occurring health and social disadvantage, to promote child health and development. What is already known on this topicO_LIPopulation-level evidence of maternal substance use during the first 1000 days is limited by heterogenous study designs. C_LIO_LICross-sectional surveys and self-reports illustrate low-level use from 10-18%; studies linking one-four whole-population health datasets provide estimates of 0.2-3% for more harmful use. C_LI What this study addsO_LIOf 970,000 children born 2008-2017 in NSW, Australia, 3.4% had a maternal substance use record during their first 1000 days of life in six linked administrative datasets. C_LIO_LIAdding child protection to health and death data more than doubled prevalence estimates. C_LI How this study might affect research, practice or policyO_LIPublic health intelligence to inform screening and support services for pregnant women, new mothers and children affected by maternal substance use can be enhanced using child protection data, in addition to health and death data sources. C_LIO_LINear universal health system contact during pregnancy and birth is an opportunity to initiate early support for maternal substance use and co-occurring health and social disadvantage, to promote child health and development. C_LI