If not for China 's one-child policy , world population would have hit 7 billion five years ago . Fertility rates in China , the world 's most populous nation , are declining . The average Chinese woman has only one child and is expected to give birth every two or three years by 2050 ( according to a recent study ). Policy 's unintended consequences include female infanticide , lopsided sex ratio .
If not for China 's one-child policy , world population would have hit 7 billion five years ago . Fertility rates in China , the world 's most populous nation , are declining . Supporters of the policy say it helped spur China 's double-digit economic growth . Policy 's unintended consequences include female infanticide , lopsided sex ratio .