Find the evidence.
Understand what it supports.

The researchers combined the original information about each child from seven studies. The children were about 20 months old on average; 51% were girls and 87% were White.

Seven datasets published from 1985 to 2014 contributed compatible measures. The paper does not report a six-support, one-oppose split. It fits one mixed-effects model to the combined participant data.

Children with secure relationships to both parents had somewhat better language skills on average. The difference was measurable but not large.

This is not 66 separate votes. The researchers combined studies that used different ways to measure responsive care and attachment in different groups of families.

Most of the available research involved mothers, so the review cannot make equally strong claims about every kind of caregiver.

Children were somewhat more likely to have secure attachments when caregivers noticed and responded to their needs. Many other influences still mattered.

The full sample included 145 infant-mother pairs and 83 fathers, but the separated-family subgroups were smaller. The overnight and comparison groups also differed in conflict and relationship history.

Only a small share of the infant sample fell into the frequent-overnight group. That reduces precision and makes the result sensitive to how frequent overnighting was defined.

The study raised an infant attachment concern, but frequent overnights did not predict more emotional or behavioural problems later. This does not prove benefit or show that every schedule is harmless.

Warshak presented loss of the father-child relationship as a competing risk. For children aged three to five, the reported comparison was 49% versus 7.7%. The families were not randomly assigned, so the figures show a strong relationship between overnights and continued father involvement, not proof that overnights alone prevented dropout.

The combined result from 19 studies slightly favoured shared care. It was not a large advantage and does not prove that the arrangement caused it.

The studies used different definitions of shared care, ranging from about 30% of time with each parent to equal time. That makes the combined answer less exact.

This was the largest group. The review counted each study once and did not give more influence to studies with larger samples or stronger methods.

This shows broad professional endorsement of the report's reasoning. It does not turn a literature review into an experiment or make every recommendation unanimous.

Families were not randomly assigned to legal schedules. Causal claims therefore remain vulnerable to selection, prior caregiving, income, conflict, and other differences.

The framework considers the child, each parent-child relationship, parenting capacity, coparenting, safety, and transition demands. It is a decision framework, not a validated scoring formula.

The principles concern familiar non-abusive caregivers, continuity of good-enough care, and attachment networks. They guide questions about care but do not select a custody schedule.

Nearly 80 studies were synthesized across precursors, correlates, and later outcomes. Different questions used different subsets, so 80 is not a single vote count.

The large amount of research supports average risk patterns across groups. It is not accurate enough to diagnose one child or decide one court case by itself.