"Mark of Gideon"--A pitch for family planning Book Review Summary
While Star Trek has not harped on the issue of birth control, there was an episode of the original series that discussed what can happen on a planet where birth control is considered morally repugnant and where the people are, well, prolific.
In the episode "Mark of Gideon," Captain Kirk encountered a society where the planet was so overcrowded that people were literally bumping into each other all the time. The people of the planet Gideon wanted to use a disease from Captain Kirk's body to kill some of its citizens to ease the population pressure. Although those killed with the disease would be volunteers (!), Captain Kirk wanted no part of their scheme. He tells the leader of Gideon, Hodin, that they should relieve their population problem by using other methods (e.g. birth control) instead. Their leader replies that the creation of life is so precious to his people that they would never accept birth control.
What is Star Trek really talking about here? The disapproval by some of the ready availability of contraception. Star Trek is saying that if means of contraception aren't readily available, that our planet will face a demographic and environmental crisis of Malthusian proportions which will render the earth virtually uninhabitable. The philosophy of the show would probably support family-planning counseling, subsidized birth control for disadvantaged families, sex education in the schools, and perhaps even the distribution of condoms to sexually active teenagers. While Star Trek probably wouldn't endorse China's strict "One Child" policy (which heavily fines families which have more than one child, and which, in practice, leads to forced abortions), Star Trek would view China's situation as a warning as to what can happen across the globe without sensible family-planning programs.
Note: the views expressed here are only those of the reviewer(s).