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Discussion with colleagues about shared parenting. What is the evidence base? Some key studies in this thread. Please do add to the thread with other studies. 
Bergstrom et al (2015) https://jech.bmj.com/content/69/8/769 Children in joint physical custody suffered from less psychosomatic problems than those living mostly or only with one parent but reported more symptoms than those in nuclear families.
Nielsen (2018) https://www.tandfonline.com/doi/abs/10.1080/10502556.2018.1454204 Review of 60 studies - children in joint physical custody had better outcomes on all measures in 34 studies, equal outcomes on some and better outcomes on other measures in 14 studies.
Fransson et al (2014) https://pubmed.ncbi.nlm.nih.gov/26553250/ Psychological complaints were lower among adolescents in joint physical custody than in adolescents in sole parental care. The difference was not explained by parental ill-health or socioeconomic variables.
Turunen (2017) https://www.tandfonline.com/doi/abs/10.1080/10502556.2017.1325648 The results show that children sharing residence equally have lower likelihood of experiencing high levels of stress.
Laftman et al (2014) https://pubmed.ncbi.nlm.nih.gov/24662307/ The study suggests that joint physical custody is associated with a higher inclination to use parents as a source of emotional support and better subjective health than other post-divorce family types.
Nielsen (2017) https://doi.apa.org/doiLanding?doi=10.1037%2Flaw0000109 The quality of the parent–child relationship is a better predictor than conflict of children’s outcomes, with the exception of the most extreme forms of conflict to which some children are exposed.
Steinbach (2019) https://pubmed.ncbi.nlm.nih.gov/29963700/ Review & critique of 40 studies. Empirical evidence suggests joint physical custody can have positive effects on the well-being of children and of parents. Further research required.
Fransson et al (2018) https://link.springer.com/article/10.1007/s12187-017-9443-1 Results showed most outcomes were similar for children with shared residence & those living with two custodial parents in the same household.
As always - important to be aware of the evidence base, BUT decisions on an individual child's arrangements need to be based on a specific consideration of that child's circumstances. Any such assessment needs to include the whole family, history and current context.
