Much of the literature on fertility transition presumes that women birth control is practiced either to limit family size or to space births. This paper argues that women also use contraception to postpone pregnancy. Postponement is not synonymous with spacing. It arises when women delay their next birth for indefinite periods for reasons unrelated to the age of their youngest child, but without deciding not to have any more children. Postponement has a distinctive impact on the shape of birth interval distributions that differs from those of family size limitation, birth spacing, or a mixture of the two behaviours. Some populations, such as that in South Africa, have developed fertility regimes characterized by birth intervals far longer than can be accounted for by birth spacing. Postponement of further childbearing that eventually becomes permanent may be an important driver of the transition to lower fertility in sub-Saharan Africa.
Timaeus & Moultrie 3The main immediate motivation for using contraception is obvious: it is to avoid pregnancy, or at least to reduce the risk of conception associated with sexual intercourse. In other words, contraception is used for birth control. The reasons why women and their partners may wish to avoid pregnancy and childbearing are many and varied. However, much of the demographic literature on fertility transition classifies motives for birth control into two mutually exclusive and exhaustive theoretical categories -the limitation of family size and the spacing of births.This paper suggests that a third important motive exists for using contraception. It is to postpone or delay pregnancy and giving birth. Birth postponement is not synonymous with birth spacing. It is conceptually distinct and has a different impact on birth interval distributions. Fertility regimes characterized by very long birth intervals cannot arise from spacing but can only be explained by widespread postponement of births achieved by contraceptive and other means. Postponement can have a substantial impact on aggregate fertility. In particular, it may be an important driver of fertility decline in Africa.The arguments just summarized are developed in successive sections of the paper. The first of these critically reviews the literature on fertility intentions and motivations for contraceptive use. It argues that the substantive, measurement, and programmatic concerns of demography have tended to direct researchers' attention away from careful consideration of reasons for practicing birth control other than family size limitation. While the importance of distinguishing postponement of births from spacing of births has been pointed out before, it has not become part of the commonplace wisdom of everyone studying fertility transition.The second substantive section of the paper considers birth interval distributions. It argues that the impact of contraceptive use on the duration-specific hazard of giving birth differs depending on whether contraception is being used for stopping, spacing, or post...