Building a family: unplanned events.

Couples in developed societies are often unsuccessful in achieving precise family building goals despite the widespread use of birth control. Unplanned events that frustrate reproductive intentions to varying degrees include contraceptive failure, sterility, miscarriage, prolonged conception delay, undesired sex combination of offspring, divorce, and the death of a spouse or a child. This paper reviews the probability of the occurrence of these events using US data. It is concluded that the large majority of newlyweds will experience at least one unplanned event during the family building phase of the life cycle.