在线词典

The natural fertility method of birth control is a concept developed by the French historical demographer Louis Henry to refer to the level of fertility that would prevail in a population that makes no conscious effort to limit, regulate, or control fertility, so that fertility depends only on physiological factors affecting fecundity. In contrast, populations that practice fertility control will have lower than "natural fertility" levels as a result of delaying first births (a lengthened interval between menarche and first pregnancy), spacing out the intervals between births, or stopping child-bearing at a certain age.