If you want a more joint physical custody you can give the parent with less parenting time more time with the child. (custodyxchange.com)
And children become alienated against custodial parents (traditionally mothers), as well as parents with less parenting time (traditionally fathers). (newways4families.com)
If this is the case, these mothers may view their infants as more difficult and report less parenting satisfaction. (academic.oup.com)