BACKGROUND: Maternal obesity is known to be associated with a range of adverse outcomes, both for the mothers and their children. It may be more prevalent in areas with higher deprivation as measured by the Index of Multiple Deprivation (IMD), but this has not been demonstrated consistently. This study focused primarily on the relationship between maternal obesity and deprivation in a setting where areas of significant deprivation are surrounded by the overall affluent South East England. METHODS: The study used the records of 3830 women who delivered under the care of a Portsmouth hospital from 1 April 2013 to 31 March 2014. Logistic regression was used to analyse the association between national IMD quintiles and maternal obesity, accounting for the potential confounders of age, ethnic origin, smoking status and parity. RESULTS: Following adjustment, women in the most deprived IMD quintile were 1.60 (95% CI: 1.13, 2.26) times more likely to be obese compared to those in the least deprived quintile. Maternal obesity was also found to be associated with ethnicity and parity, but not with age or smoking status. CONCLUSIONS: Maternal obesity increased with increasing deprivation. IMD may be a useful group-level indicator when planning interventions aimed at tackling maternal obesity.