Table 1.

Eligibility criteria

	Inclusion Criteria	Exclusion Criteria
Population	Pregnant women - studies with infants as the primary population of interest were included if multimorbidity during pregnancy was analysed in relation to outcomes within the first year of life.	Non-pregnant women, men, or children.
Exposure	Multimorbidity or multiple conditions, including infectious diseases, NCDs*, mental health conditions, environmental exposures, and substance use disorders.	Single chronic conditions, without considering the impact of multimorbidity.
Outcome	Neonatal and perinatal outcomes (e.g. preterm birth, low birth weight, neonatal mortality) within one year after birth.	No relevant perinatal or neonatal outcomes reported within the first year of life.
Design	Studies of observational or interventional design with more than 100 participants, published after January 1 st, 2015, in any language or location.	Publications with unclear methodologies or incomplete data, or of non-observational study designs such as reviews, editorials, and letters to the editor. Animal studies and laboratory-based research were excluded to maintain the scope of this study.

*NCDs defined in our review as: physical conditions not caused by infectious agents that often cause chronic health consequences and require long-term treatment or care. Physical NCDs were separated from mental health conditions to provide additional analysis on how these exposures impact neonatal and perinatal outcomes