It is a fact that more developed (i.e. more medically advanced) countries have a lower birth rate: (http://www.project-syndicate.org/commentary/the-end-of-popul...) As we gain more technological freedom to control our own fertility, and as having children becomes a bigger economic disadvantage, the population growth rate has slowed considerably in countries with access to medicine. The countries that do not have advanced medicine available to the public - China, India, other developing countries - are the ones with enormous population booms that are damaging to the planet.

Our ability to remain fertile at any time of year due to food production is greatly offset by our ability to control our birth rates. In fact, if you're concerned about our longevity, our replacement rate (the rate at which old people die and new people are born) is extremely tight, last I've heard, I'm not sure what the ratio is at now. I find it totally untenable to blame medicine for world overpopulation or "giving the middle finger to nature" when it's provable that medicine is a direct, causal link to population growth slowing.