BackgroundFood insecurity is an increasingly important public health concern in high-income countries following the 2008 global financial crash, and recently with the COVID-19 pandemic. Food insecurity has been understood as a highly gendered issue, affecting more women than men. As women have more complex nutritional needs because of their menstrual cycle, pregnancy, and breastfeeding, the nutritional impact of food insecurity is also greater for women than for men. This systematic review aims to explore pregnant women's experiences of food insecurity in high-income countries and to understand how food insecurity affects their health, wellbeing, diet, and nutrition. MethodsWe did a systematic review following PRISMA reporting guidelines. A comprehensive search strategy was developed using search terms such as “food insecurity” and “pregnancy outcomes”. We searched seven databases (MEDLINE, Embase, Scopus, Web of Science, PsychInfo, ASSIA, and CINAHL), grey literature, reference lists, and citations, as well as contacted authors. No language restrictions were used, and only studies primarily containing data collected from Jan 1, 2008, onwards were included. Database searches were completed in April 2022; supplementary searches are ongoing. Inclusion criteria is based on PECOS. Screening, data extraction, and quality assessment were done by two authors independently. This systematic review is registered on PROSPERO, number CRD42022311669. Findings27 studies met the inclusion criteria, with all studies published between 2015 and 2022. 24 (89%) of 27 studies were done in the USA, two (7%) in Canada, and one (4%) in the UK. Outcomes reported include dietary intake or dietary quality during pregnancy (seven [26%] of 27), gestational weight gain (seven [26%]), mental health (five [19%]), pregnancy outcomes including pregnancy complications, preterm birth, or birthweight (five [19%]), and other health outcomes or combination of nutrition, health, and wellbeing (three [11%]). Evidence synthesis is ongoing and will be complete by August, 2022. InterpretationThis systematic review suggests that food insecurity experienced during pregnancy was associated with negative health and nutrition outcomes. The rigorous searches are strengths of this study. A limitation is the restricted focus on studies done from 2008 onward. More research to guide efficient interventions that address food insecurity among pregnant women is needed. FundingNone.