Pregnancy in a diabetic woman brings about many changes that can lead to the development of diabetic retinopathy (DR) or worsening of pre-existing disease. In some patients this may develop into sight threatening disease which, if not treated adequately, can cause devastating visual impairment. There is a lack of established guidelines for screening these patients during pregnancy. In this article we discuss the physiological changes during pregnancy that contribute to worsening of diabetic retinopathy and review the relative contribution of risk factors to the underlying pathological processes. It is important to identify and treat any pre-existing retinopathy in diabetic women considering pregnancy and optimise glycaemic control prior to conception. Rapid tightening of glycaemic control after conception is associated with a less favourable outcome. Based on the existing literature we suggest guidelines for diabetic retinopathy screening for women during pregnancy. Established sight-threatening retinopathy should be treated at an earlier stage in pregnant women compared to non-pregnant diabetics with a similar disease.