The issue is certainly one that socialists cannot ignore.
An article in the June edition of Scientific American discusses population
This aspect of the issue is an interesting one. Firstly, Socialism will entail the end of the State, so there is no question of some sort of central authority controlling family size, such as in China. Secondly, as we argue in our principles: "That as in the order of social evolution the working class is the last class to achieve its freedom, the emancipation of the working class will involve the emancipation of all mankind, without distinction of race or sex."
Mostly ignored in the environmental debates about population and consumption is that nearly all the world’s nations agreed to an altogether different approach to the problem of growth 15 years ago, one that bases positive demographic outcomes on decisions individuals make in their own self-interest. (If only something comparable could be imagined to shrink consumption.) The strategy that 179 nations signed onto at a U.N. conference in Cairo in 1994 was: forget population control and instead help every woman bear a child in good health when she wants one.
That approach, which powerfully supports reproductive liberty, might sound counterintuitive for shrinking population growth, like handing a teenager the keys to the family car without so much as a lecture. But the evidence suggests that what women want—and have always wanted—is not so much to have more children as to have more for a smaller number of children they can reliably raise to healthy adulthood. Women left to their own devices, contraceptive or otherwise, would collectively “control” population while acting on their own intentions.
The article notes that better family planning services, access to contraception, sexual equality and (female) education all play an important role in reducing birth rates. Religions, with their superstitions and "laws", have a baneful influence - e.g. Catholicism and its views on contraception (which also acts against the prevention of HIV/AIDS).
It would appear that eliminating poverty is a way to achieve a stable world population. Needless to say, there are many wrinkles and complexities in the population, resources and environment issue. Our case is that Socialism is the best framework for abolishing that poverty and liberating women.
Population and Resources SPGB educational document
What Causes Famines? and How Many Die of Famine? Socialist Standard 1985 (.pdf)
Enough For All Socialist Standard 2005
Malthus' Essay on Population at Age 200. A Marxian View by John Bellamy Foster
How the Other Half Die by Susan George