IntroductionCurrently, the adherence to nutritional guidelines is low, with alarming rates of obesity worldwide and micronutrient deficiencies documented even in industrialised countries. As a consequence, nutritional screening and counselling represent a critical subject in early pregnancy, aiming to improve pregnancy outcomes and population health.Methods and analysisIn this setting, the development of a simple and reproducible nutritional checklist is of utmost importance. The Simple Study is a longitudinal prospective multicentre study aiming to identify the associations between maternal nutritional habits in the first trimester, early markers of placental function and pregnancy outcomes on a large population of singleton pregnancies in Italy.Ongoing healthy singleton pregnancies will be enrolled at the ultrasound scan of the first trimester combined screening test (11⁺⁰–13⁺⁶gestational weeks). A nutritional score measuring the adherence to a healthy diet and nutritional deficiencies will be collected at recruitment. Fetal (crown-rump length, nuchal translucency (NT), biparietal diameter, femur length) and utero placental (placental volume, uterine arteries Doppler velocimetry) ultrasound data and biochemical placental markers (pregnancy-associated plasma protein A, free ß-human chorionic gonadotropin) will be collected. Second and third trimester ultrasound records and birth outcomes will be recorded from medical registers. This study will set the stage for introducing a reproducible, time-saving and low-cost nutritional screening in pregnancy. The nutritional score will allow the implementation of specific corrective measures with potential large impact on placentation and pregnancy outcomes.Ethical and disseminationEthical approval for this study was obtained from the Milano Area 1 Ethics Committee (No 46091, 7 November 2018) prior to the commencement of the research.The dissemination plan includes the presentation of abstracts and findings at national and international scientific meetings.