This study is being conducted to investigate how a mother's nutritional status and her gut microbiome during pregnancy contribute to the birth outcomes and health of her baby. The gut microbiome is the totality of microorganisms (e.g. bacteria, viruses, fungi) living in the gastrointestinal tract. This study will focus on pregnant women, 28 years and younger living in the Toronto and greater Toronto area. The focus is on younger women due to their vulnerability to undernutrition. Pregnant participants, and upon delivery, their newborns will be followed throughout pregnancy and for a year afterwards. Throughout this period, the investigators will collect stool samples, rectal swabs, blood samples, health assessments, nutritional and dietary assessments and birth/ labour details. The goal is to define the relationship between a mother's nutritional status and her microbiome dynamics during pregnancy and how they contribute to the birth outcomes and growth of her newborn. With the hypothesis that alterations of the microbiota in the maternal gut (dysbiosis) exacerbated by nutritional status or pathogen exposure during pregnancy, impacts weight gain because of impaired nutrient absorption, leading to corresponding negative birth outcomes.