Mostly, the regions where the USA is involved are very highly populated. With all due respect to the war in Iraq, it's not even a dint in the Iraqi rate of birth. Same goes for Israel, same goes for Afghanistan, same goes for the Palestinian territories.

All those wars don't stop people from going forth and multiplying. And even though there are some hungry people, it doesn't even come close to places in Africa where the wars don't need encouragement from the USA.

In short, nobody limits the number of children in the ROW, and nobody forces a high quota of children in the USA.