BACKGROUND:Some women with diabetes in pregnancy are encouraged to express and store colostrum prior to birthing. Following birth, the breastfed infant may be given the stored colostrum to minimise the use of artificial formula or intravenous dextrose administration if correction of hypoglycaemia is required. However, findings from observational studies suggest that antenatal breast milk expression may stimulate labour earlier than expected and increase admissions to special care nurseries for correction of neonatal hypoglycaemia. OBJECTIVES:To evaluate the benefits and harms of the expression and storage of breast milk during late pregnancy by women with diabetes. SEARCH METHODS:We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2014). SELECTION CRITERIA:All published and unpublished randomised controlled trials comparing antenatal breast milk expressing with not expressing, by pregnant women with diabetes (pre-existing or gestational) and a singleton pregnancy. DATA COLLECTION AND ANALYSIS:Two review authors independently evaluated reports identified by the search strategy. MAIN RESULTS:There were no published or unpublished randomised controlled trials comparing antenatal expressing with not expressing. One randomised trial is currently underway. AUTHORS' CONCLUSIONS:There is no high level systematic evidence to inform the safety and efficacy of the practice of expressing and storing breast milk during pregnancy.