Speech and language delays in infants and children occur when speech and language abilities are below that expected for a child’s chronological age, while still following the expected developmental sequence . Speech and language development is known to be an important overall developmental milestone in children and early speech and language delays can result in poorer educational outcomes and longer term adverse cognitive and behavioral outcomes throughout the life course . Although the prevalence of speech and language disorders depends on their exact classification and definition, recent studies suggest that some communication disorders may be as high as 13% in primary and secondary school children [3, 4].
Research on the predictors of late language emergence at 24 months in an Australian cohort have illustrated the complexity of the predictors of language emergence in the general population showing strong neurobiological and genetic causal mechanisms that operate across a wide variation in maternal and family characteristics . Speech and language impairments are often one of the key features of neurologic damage in children with diagnoses of Fetal Alcohol Spectrum Disorders (FASD) which are as high as 5% in some regions of the United States and Europe [6–8]. However, while the impact of alcohol consumption during pregnancy on birth outcomes , mental development  and neuropsychological outcomes  is well investigated, the effect of alcohol consumption during pregnancy on speech and language development especially at lower or moderate levels is unknown .
In Denmark, the Netherlands, Australia, the United Kingdom, Ireland and the United States a number of large population-based longitudinal and cross sectional studies have estimated that between 12% and 81% of babies may be exposed to alcohol during gestation due to maternal alcohol consumption [13–20]. While most women who consume alcohol during pregnancy do so at low or moderate levels, the exact consequences of these levels of alcohol on fetal growth and development have not been established. Recent reviews have suggested that moderate drinking may not be harmful to birth weight, length of gestation or size for gestational age [9, 21]. However, evidence suggests that low to moderate alcohol use in pregnancy can still produce functional damage to the brain leading to adverse cognitive and neurological development without obviously affecting other systems such as growth . Specifically, magnetic resonance imaging (MRI) studies have shown that prenatal alcohol exposure can impact on many areas of the brain involved in speech and language development, including the corpus collosum .
At present in Canada, the United States, Ireland and New Zealand recommendations advise complete abstinence from alcohol during pregnancy due to uncertain evidence on its effect on growth and development at lower to moderate levels [23–26]. However, the National Institute for Health and Care Excellence in the United Kingdom suggest that one to two units not more than once or twice per week is safe . Establishing the impact of gestational alcohol exposure on speech and language outcomes in children is an important contribution toward understanding, both in the etiology of adverse speech and language development and in developing consistent and comprehensive clinical and government guidelines internationally around alcohol use during pregnancy.
The aim of this review was to systematically search and appraise available case control and cohort studies on the effect of low to moderate alcohol use during pregnancy compared to abstinence from alcohol during pregnancy on speech and language outcomes in children to age 18 years.