This has been observed since Scandinavian countries pushed very female-friendly work laws, only to have differences in gender preferences more marked than ever. The book The Nordic Gender Equality Paradox submits two pieces of explanation to it, which are that 1/ One of the reforms was to offer sumptuous parent leave, encouraging parents to distance themselves from work for a significant duration, but which made the mothers gain less experience than the fathers who usually don't take the leave and 2/ Those reforms incurred strong taxes and diminished spending power, more especially making child care less affordable, again distancing mothers from work.