The study is based on the Developmental Origins of Health and Disease (DOHaD) study, a total population nationwide cohort including all individuals born in Sweden since 1973. The cohort comprises 5,751,581 births, with detailed information on perinatal outcomes and familial socioeconomic and health histories. This is made possible through record linkage of several national and regional health and administrative registers, including, for example, the Medical Birth Register, the National Patient Register, the Prescribed Drug Register, the Cause of Death Register, and the Longitudinal Integrated Database for Health Insurance and Labour Market Studies (LISA). Time series and case time series designs will be used to evaluate the effect of non-optimal temperature and precipitation pregnancy, neonatal and other health outcomes in children and adolescence (< 18 years of age). Using time series analysis, we will quantify the excess risk associated with non-optimal temperatures and precipitation. We will also explore the role of potential effect modifiers, such as maternal age, geographical location, and socio-economic determinants. Interactions with other climatic variables, exposure lags, and the fraction of events attributable to non-optimal temperature and Precipitation.