BackgroundNutritional status critically contributes to maternal and child morbidities and mortality. Undernutrition during pregnancy and preconception is linked to adverse pregnancy and birth outcomes and has downstream effects on the growth and development of children. The gut microbiome has a profound influence on the nutritional status of the host. Dysbiosis has emerged as a major factor in the development of malnutrition. This phenomenon is understudied in settings with a high prevalence of undernutrition, and further investigation is warranted to better understand such interactions.MethodsThe study is a prospective, longitudinal observational study to investigate the impact and relationship between prokaryotic and eukaryotic microbes in the gut and their association with maternal health and birth outcomes among young women, 17-24 years of age in Matiari District, Pakistan. We aim to enroll 400 pregnant women with low and normal BMIs at the time of recruitment (<16 weeks of gestation). Data collection includes demographics, morbidities, medication use, empowerment, dietary recall, and anthropometrics. Stool and blood specimens are collected at several time points for different laboratory assays.DiscussionLimited studies have examined the role of the microbiome in maternal health and birth outcomes where the prevalence of undernutrition is high. Here we aim to investigate the interplay of maternal and child undernutrition with the composition (diversity) and functionality of the gut microbiome and capture how it is influenced by environmental and genetic factors. Findings are expected to provide valuable insights into the understanding of undernutrition.Study registrationThe study is registered withClinicalTrials.govIdentifier:NCT05108675.