Objective: To analyse the factors associated with the level of adherence to a Mediterranean dietary pattern in healthy Spanish women before pregnancy. Design: A prospective series of 1175 women. An FFQ validated in Spanish populations served to collect dietary data. The Mediterranean Diet Adherence Index was used to assess the level of adherence to a Mediterranean diet pattern. Polytomic regression was performed to identify the associated factors. Setting: Catchment area of Virgen de las Nieves University Hospital, Andalusia, Spain. Subjects: The women were invited to participate in the study at the 20th-22nd gestational week. The selection criteria were: Spanish nationality, 18 years of age or older, singleton pregnancy and absence of health problems that required modifying the diet or physical activity. Results: An inverse relationship was found between women's age and level of adherence to a Mediterranean diet pattern, with a clear dose-response association: a younger age entailed worse adherence (P , 0?001). The habit of smoking and sedentary lifestyle had a positive relationship with low adherence, giving OR 5 5?36 (95 % 1?91, 15?07) for women who smoked .20 cigarettes/d and OR 5 2?07 (95 % CI 1?34, 3?17) for sedentary women. Higher age, higher educational level, and higher social class of the women were associated with a higher level of adherence to the Mediterranean diet (P , 0?001). Conclusions: In our sample population, younger age, lower social class, primary educational level and elements of an unhealthy lifestyle such as smoking and lack of exercise were associated with low adherence to a Mediterranean diet.