Background Since 2008, use of food banks has risen sharply in the UK; however, evidence on the epidemiology of UK food insecurity is sparse. The aim of this study was to describe the trajectory of common mental disorder across the pre-pregnancy, pregnancy and postnatal period for food secure compared with food insecure women.

Methods Data from the Born in Bradford (BiB) cohort, the nested BiB1000 study and primary care records were linked based on National Health Service (NHS) numbers. Data linkage was completed for 1297, and primary care records were available from 18 months prior to 40 months after birth of the cohort child. Incidence rates of common mental disorders per 1000 patient years at risk were compared between food secure and insecure women, and for Pakistani compared with white British women, in 10 6-month periods around pregnancy. Poisson regression was used to calculate incidence rate ratios, adjusted for ethnicity and exposure.

Results Food insecurity was significantly associated with an increased risk of common mental disorder before and during pregnancy (incidence rate ratio 1.9, 95% confidence interval 1.3 to 2.8, p=0.001) and after giving birth (incidence rate ratio 1.3, 95% confidence interval 1.0 to 1.7, p=0.029).

Conclusions Our study shows that food insecure women have worse mental health than food secure women, and that this difference is most pronounced for white British pregnant women. These findings provide evidence for concerns expressed by public health experts that food insecurity may become the next public health emergency.