Both obesity and vitamin D deficiency are linked to morbidity and ultimately mortality. Vitamin D sufficiency is believed to confer many health benefits; however, with the exception of the classic functions related to bone health these are not yet well understood, especially in relationship to pregnancy and infant health outcomes.1 Conversely, insufficiency is associated with adverse health outcomes, which are consequently related to public health concerns that arise from these and these need addressing.2,3 While the links between health and vitamin D are being considered and researched, there are an increasing number of reports that demonstrate vitamin D deficiency is prevalent particularly among people who are darker skinned, those who live at latitudes above 52°, and are therefore exposed to reduced sunlight especially in the autumn and winter months, those who through lifestyle choices cover their bodies, preventing sunlight exposure, and in obese people.3-6 Obesity is also of growing concern. Health journalists and academics sometimes dramatically refer to 'obesity epidemics,' which is not surprising as over one-third of Americans are obese.7-9 This problem, if not addressed, will lead to adverse health outcomes for individuals as well as being a long-term burden both to families and society.10-11 It is interesting to note that both vitamin D deficiency and obesity have shared risks for mortality and morbidity including cardiovascular disease, diabetes, respiratory problems, cancer and musculoskeletal disease. This paper considers current concepts and the links between obesity and vitamin D deficiency in pregnancy seeking to determine whether being vitamin D deficient and obese is simply double trouble, where both are present, or whether there are there other factors that need further exploration, reviewing the associated implications for practice.12-15.