Background: Pregnant women in Great Britain were recommended to receive influenza A(H1N1)pdm09 vaccines during the 2009/10 influenza pandemic, however uptake of the vaccines by pregnant women was reported to have been very low. Aim: We sought to estimate uptake of influenza A(H1N1)pdm09 vaccines and to investigate predictors of vaccine uptake in pregnant women in Great Britain during the 2009/10 pandemic. Methods: Uptake rates were calculated using data from the UK General Practice Research Database (GPRD). Predictors of vaccination were identified using a Cox proportional hazards model. Results: Uptake of influenza A(H1N1)pdm09 vaccines by pregnant women was 21.6%. Pregnant women with an underlying health condition increasing the risk of influenza-related complications had a higher vaccination rate than pregnant women without such conditions. The hazard ratio comparing these two groups decreased logarithmically throughout pregnancy from 9.3 in the first week to 1.3 by the end of pregnancy. Increasing maternal age (HR 1.01, CI 95 1.01-1.01), having a previous delivery recorded (HR 1.21, CI 95 1.16-1.27) and living in Scotland (HR 2.58, CI 95 2.34-2.85) or Wales (HR 1.37, CI 95 1.20-1.57) as opposed to England were all also associated with an increase in vaccination uptake rates throughout pregnancy. Discussion: Uptake of influenza A(H1N1)pdm09 vaccines by pregnant women was low. None of the potential predictors evaluated in this study were strong enough to account for this, however information on health beliefs and GP recommendation were not available. If the low rates reported here are to be improved new strategies to increase uptake of influenza vaccine in pregnant women need to be identified, evaluated and implemented.