The intrauterine developmental consequences of phenobarbital, when administered in varied doses, on foetal growth and development remain poorly understood. This study is therefore set to evaluate the intrauterine effects of phenobarbital at differing doses when administered at different incubation periods in albino rats. In carrying out this study, a post-test only control experimental study design was adopted, and a sample size of 30 Albino rats was used. These rats were obtained from the Small Animal Facility for Research and Innovation in the School of Biomedical Sciences at Jomo Kenyatta University of Agriculture and Technology. They were arbitrarily allocated into two large study groups of 3 control rats and 27 experimental rats. The 27 rats in the experimental group were further subdivided into three study groups of 9 rats, each with low, medium, and high phenobarbital doses. On gestation day 20, all the rats were humanely sacrificed, and three fetuses from each rat were selected. The parameters evaluated in this study included the foetal weight, bi-parietal diameters, and crown lump length. The data was collected using a structured checklist, then entered into the computer using an Excel spreadsheet. The data was then exported to the Statistical Package for the Social Scientist (SPSS). To determine the causal effects, the statistical significance was determined by using Tukey’s post hoc multiple comparison tests, and all values with a p value less than 0.05 were considered to be significant. This research discovered that there was a reduction in all foetal parameters, which was statistically significant (P<0.05), especially during trimesters one and two. The effects of phenobarbital administered on foetal parameters depended on the time of exposure and dose administered. Phenobarbital, administered prenatally, had dose- and time-dependent effects on foetal parameters. Therefore, more studies need to be done on higher primates to ascertain their teratogenic safety in pregnancy.