Effects of various factors on selection for family planning status and natural fecundability: a simulation study.

The effect of various factors on selection for family planning status and for natural fecundability is studied in a simulation that incorporates a beta distribution of fecundability among women. The mean fecundabilities of current spacers, current limiters, current nonusers, and pregnant women are compared. These ratios are influenced by duration of marriage and by desired number of children. Effects of different levels of contraception are measured. Another strategy, spacing the last two wanted births, is also studied. It is found that breast-feeding status has little effect on fecundability selection. The women usually found to have greatest fecundability are not those recently pregnant at durations of marriage five and ten years, unless they wanted fewer than two children, but rather those who are using contraception to limit the number of children.