MISA began with MISA 1, which recruited 391 pregnant women from Northern Norway between May 2007 and June 2009. Participants were invited by mail after scheduling a pregnancy ultrasound at one of eight selected delivery units or two antenatal centres. MISA 1 focused on the effects of environmental toxins during pregnancy and breastfeeding, with follow-ups conducted during pregnancy, at delivery, three days postpartum, and six weeks postpartum. In autumn 2017, MISA 2 was launched to expand the study’s scope, incorporating diet and lifestyle factors to assess the broader environment provided by pregnant women to themselves and their babies. It also examined the life circumstances of young women who had not yet had their first child. Data collection for MISA 2 concluded in 2024, including a total of 354 participants, 105 of whom were mother-child pairs during the breastfeeding period, with the overall MISA project set to conclude in 2033.