“…Lone vs. Cohabiting motherhood and mental health. In the social expenditure group, all studies used social expenditure as their main exposure, however, authors used different labels for this concept such as Social expenditure (Dumbraveanu, 2015;Yur'yev, 2012;Knoll and Pitlik, 2016;Ono and Lee, 2013), Social spending (Baumbach and Gulis, 2014), Welfare generosity (Clench-Aas and Holte, 2018), Government expenditure (Flavin et al, 2011) and Government size (Composed of various public/social expenditure categories: defence, education, health, public order and safety, economic, general public services, social protection, other; Hessami, 2010). Hence, we grouped studies based on their primary outcome measures: 1.…”