The effects of maternal alcohol and cigarette use during lactation on cognitive, developmental and academic outcomes in later childhood

Background

While alcohol and tobacco are known teratogens, whether their intake while breastfeeding can negatively impact children has been scantly researched. In particular, the potential effects on cognition, academic achievement, developmental health, and risk of developmental disorders have largely not been assessed. This thesis aimed to examine whether drinking or smoking while breastfeeding lowers children’s cognitive (Chapter 1) and academic (Chapter 2) scores, developmental health (Chapter 4), and increases Attention Deficit/Hyperactivity disorder (ADHD) or Autism Spectrum Disorder (ASD) risk (Chapter 5). It was hypothesised that increased drinking or smoking would be dose-dependently related with reduced cognitive, academic, and developmental health scores, and would increase ADHD and ASD risk. An additional investigation described demographic, lifestyle, and maternal alcohol and tobacco intake differences between children from language backgrounds other than English (LBOTE) and children from English language backgrounds (ELB) (Chapter 3). 

Methods

Data was sourced from Growing Up in Australia: The Longitudinal Study of Australian Children. Participants were 5107 Australian infants and caregivers recruited in 2004, and assessed every two years. Multivariable linear regression analyses assessed relationships between drinking and smoking habits of breastfeeding mothers at Wave 1 (study entry), and children’s Matrix Reasoning, Peabody Picture Vocabulary Test–Third Edition and Who Am I? scores (Chapter 1), Australian national standardised academic assessments (National Assessment Program–Literacy and Numeracy; NAPLAN) (Chapter 2), and Pediatric Quality of Life Inventory (PedsQL) Generic Core Scales (Chapter 4). Logistic regression assessed ADHD or ASD risk (Chapter 5). Kruskal-Wallis H tests and analyses of variance assessed differences between LBOTE and ELB children (Chapter 3). 

Results

Increased or riskier Wave 1 maternal alcohol consumption was associated with reduced Matrix Reasoning scores at age 6-7 years in children who had been breastfed (B=-0.11;SE=0.03;95%CI:-0.18-(-)0.04;p=0.01) (Chapter 1), and reduced Grade 3 NAPLAN writing (B=-1·56;SE=0·49;95%CI:-2·52-(-)0·60;p=0·01), spelling (B=-2·06;SE=0·63;95%CI:-3·31-(-)0·81;p ˂0·0001) and grammar and punctuation (B=-2·11;SE=0·75;95%CI:-3·59-(-)0·64;p=0·01) scores, as well as Grade 5 spelling scores (B=-1·58;SE=0·59;95%CI:-2·74-(-)0·43;p=0·03) (Chapter 2). These relationships were not evident in babies who had never been breastfed. No relationship between maternal consumption of alcohol during lactation and any other outcome variable was observed (Chapters 1,2,4,5). Smoking during lactation was also not associated with any outcome variable (Chapters 1,2,4,5). Additionally, it was noted that LBOTE breastfed children had the same or superior academic performance as ELB children across all NAPLAN tests. The mothers of LBOTE children (n= 151;M=3.09;SD=2.48) also had lower or less risky patterns of alcohol consumption while breastfeeding than mothers of ELB children (n=1338;M=5.83;SD=2.29;χ2=126.69;p˂0.001) (Chapter 3). 

Conclusions  

Maternal alcohol consumption while breastfeeding, but not cigarette use, may be associated with cognitive and academic reductions. While the relationships were small, they may be clinically significant if mothers consume large quantities of alcohol, regularly binge drink, or if children have comorbid disorders. Given the dose-dependent relationship, no safe amount of alcohol can be established. The safest option for breastfeeding women may be to abstain from alcohol consumption and nicotine use during lactation. Future research should measure ethanol dose to infants, and assess a wider range of outcome variables.