John P. Holdren, from the Obama administration in his writing in '73 says,("It would even be possible to require pregnant single women to marry or have abortions,)

John P. Holdren, from the Obama administration in  his writing in '73 says,("It would even be possible to require pregnant single women to marry or have abortions,)
  From this text,"Indeed, it has been concluded that compulsory population-control laws, even including laws requiring compulsory abortion, could be sustained under the existing Constitution if the population crisis became sufficiently severe to endanger the society.

One way to carry out this disapproval might be to insist that all illegitimate babies be put up for adoption—especially those born to minors, who generally are not capable of caring properly for a child alone. If a single mother really wished to keep her baby, she might be obliged to go through adoption proceedings and demonstrate her ability to support and care for it. Adoption proceedings probably should remain more difficult for single people than for married couples, in recognition of the relative difficulty of raising children alone. It would even be possible to require pregnant single women to marry or have abortions, perhaps as an alternative to placement for adoption, depending on the society."