The Prospective Epidemiological Research Studies in IrAN (PERSIAN) Birth Cohort protocol: rationale, design and methodology

Background: Birth cohorts are essential for developing evidence-based policies and advancing knowledge on different aspects of the concept of developmental origins of health and diseases (DOHaD). The Prospective Epidemiological Research Studies in IrAN (PERSIAN) is a multicentre cohort in Iran. It is one of the pioneers of DOHaD research in the Middle East and North Africa (MENA) region. This profile provides a brief overview of this birth cohort, focusing on the objectives and design of the study. The main objective of this birth cohort is to evaluate the associations of socio-economic characteristics, lifestyle, diet, environmental exposures and epigenetic factors with outcomes of: pregnancy; mother and child mental and physical health and well-being; child neurodevelopment; and the establishment of chronic disease risk factors. Methods: The enrolment of PERSIAN Birth Cohort participants is currently ongoing in five Iranian cities (Isfahan, Yazd, Semnan, Sari and Rafsanjan). We plan to recruit 15,000 mother-offspring pairs, and to follow them for at least ten years. Data collection consists of three consecutive phases: (1) periconception until birth; (2) infancy (0-2 years); and (3) childhood (3-11 years). We are collecting data on both 'determinants of health' and 'health outcomes'. In addition to questionnaires and physical examination, various biological samples, including blood, urine, hair, nail, cord blood and breastmilk are being collected. Growth and neurodevelopment of children will be monitored. Appropriate data analysis schemes will be employed to assess the role of early life factors in health and disease that would facilitate international comparisons.