Download files
Abstract
The association between heavy prenatal alcohol exposure (PAE) and impaired cognitive development in children has been well documented, yet uncertainty remains regarding the effects of low-level PAE. This thesis, after reviewing evidence in Chapter 1, and analysing that evidence (Chapter 2) addressed this issue with a particular focus on delineating effects of alcohol teratogenesis from those of associated environmental factors.
In Chapter Two, the extent of intellectual impairment among children with fetal alcohol spectrum disorders (FASD) or PAE was reviewed using meta-analysis. Findings confirmed intellectual impairment occurs in FASD, quantifying the extent of this impairment across studies; no impairment was evident in children with low PAE.
The remaining empirical chapters reported findings from a longitudinal pregnancy cohort study. Chapter Three examined the effect of PAE on infant cognitive development at 12-months. After adjustment for maternal IQ and environmental factors, no effect of PAE was seen on infant cognition.
Chapter Four focused on the time between conception and pregnancy recognition as a unique period at high risk of PAE. Alcohol use was high during this period, with binge or heavy use being common. Analysis of trajectories of change to alcohol use showed the majority of women cease or reduce alcohol consumption following recognition of pregnancy. Factors influencing trajectory of change included age, level of alcohol consumption, tobacco and illicit substance use.
Chapter Five sought to isolate effects of PAE from environmental confounders. A component of this was to examine alcohol consumption by partners, which was closely related to alcohol use by mothers. Regression analyses assessed the effect of PAE on infant cognitive outcomes, complemented by the use of propensity score matching. In no analysis was PAE at any point in pregnancy linked to poorer cognitive outcomes in children after adjustment for confounders.
Together, findings herein have important implications for public health and future research. The importance of considering environmental confounders was emphasised, including the role of partners. The early period of gestation was also highlighted as being of particularly high risk for alcohol exposure, so focused research and public health interventions addressing this time period may be beneficial.