Prenatal alcohol exposure (PAE) can lead to a wide spectrum of deficits in growth and neurological function, and there is an established link between PAE and auditory dysfunction. However, the effects of PAE on auditory development are complex and vary depending on the age and pattern of alcohol exposure. In this study, we developed a mouse model of PAE during the first half of the gestational period, mimicking alcohol consumption during the first trimester of pregnancy in humans. This exposure did not affect overall growth or induce anxiety-related symptoms in the offspring, as indicated by normal body weight change and largely unchanged behaviors in the open field and elevated zero maze tests. However, several aspects of auditory function were affected by PAE. Offspring born from prenatal alcohol-exposed dams displayed smaller auditory brainstem responses (ABRs) at 2-month-old as compared to those from control dams, suggesting weakened neuron synchronization within auditory brainstem circuits. Additionally, a reduction in the reproducibility of ABR peaks III/IV was observed in PAE offspring. In contrast, the overall hearing sensitivity and neuron transmission was not affected by PAE, as evaluated by ABR thresholds or peak latencies. In an acoustic startle test, PAE offspring failed to display prepulse inhibition to low levels of prepulses more frequently than control offspring at both 2 weeks old and 2 months old, suggesting an early-onset and lasting deficit in auditory gating or sound level differentiation. Together, these results demonstrate that mice exposed to alcohol during early gestation have largely preserved auditory responses but show significant alterations in specific features of auditory processing.