During and following pregnancy, women are at considerable risk of experiencing depression. For treatment, selective serotonin reuptake inhibitor drugs, such as fluoxetine, are commonly prescribed, yet the potential effects of perinatal exposure to these drugs on the brain and behaviour have not been examined in humans beyond childhood. This is despite abundant evidence from studies using rodents indicating that altered serotonin levels early in life affect neurodevelopment and behavioural outcomes. These reported effects on behaviour are inconsistent, however, and the testing of females has often been overlooked. In the present study, the behavioural outcomes of female mice perinatally (embryonic day 15 to postnatal day 12) treated with fluoxetine (25mg/kg/day) via a non-stressful method of maternal administration were assessed using a battery of tests. Maternal treatment resulted in subtle alterations in anxiety-like and depression-like behaviour in early adulthood, with a decrease in both types of behaviour as well as body weight. Though altered anxiety and depression have previously been reported in this area of research, decreased anxiety is a novel finding. While there was little effect of perinatal maternal fluoxetine treatment on many of the behaviours assessed, the capacity to alter “emotional” behaviours in mice has implications with regard to research on human infant fluoxetine exposure.