bad quality daycare, lack of motherly sensitivity, spending more than 20 hours a week in daycare, daycare before 2 years of age.
that report also claims that daycare generally affects the socioemotional competence of children, and that 25% of children that received full day daycare by age of 4 show significant problematic behavior even if the daycare is of good quality.
the quality of parental care is the strongest factor for the development of social and cognitive development.
another article claims that kindergarten does not have a positive effect before age 4.
on the other hand another article claims that children that receive some (but it doesn't say how much) external care in the first two years of life are less likely to later have psychological illnesses, and children that start kindergarten only at 4 are twice as likely to get sick. (personally i doubt that, but there it is, research is conflicting, and the jury is still out). but that same article also claims that things have improved over time. before the 90s, early daycare had a negative effect while after the effect became positive.
i am not saying that there is only one truth, but as a supporter of the attachment theory of parenting, i tend to side with the idea of keeping kids at home early, and only introducing daycare very gradually and i can also confirm some of this with my own experience.
in austria/germany kindergarten and school traditionally is half day. afternoon childcare is considered special and very expensive, if you can even find a place. finding a space in kindergarten can be a problem too.
many parents want to send their children to childcare but they simply can't