Not all highly-educated women are staying at home purely due to lack of child-care spaces.

There will not be enough child-care workers for the extra spaces.

If the highly-educated women all tried to enter the work force, there may not be jobs for all of them, reducing the tax revenue.

There will be leakage of daycare spaces to lower-educated, lower-earning women, unless the daycare spaces were earmarked to higher-educated women - i.e. take from the poor to give to the rich. Such a reverse-Robin-Hood policy might make economic sense, but it makes for poor social policy. Only a pure economic conservative would undertake it.