There are two situations where excellent efficacy, probably near total effectualness, is achieved: lactating women and women over age 40. In lactating women, the contribution of the minipill is combined with prolactin-induced suppression of ovulation, adding up to very effectual protection. In women over age 40, reduced fecundity adds to the minipill's effects.

There is another reason why the minipill is a good choice for the breastfeeding woman. There is no evidence for any adverse effect on breastfeeding as measured by milk volume and infant growth. In fact, there is a modest positive impact; women using the minipill breastfeed longer and add supplementary feeding at a later time. Because of the slight positive impact on lactation, the minipill can be started immediately after delivery.

The minipill is a good choice in situations where estrogen is contraindicated, such as patients with serious medical conditions (diabetes with vascular disease, severe systemic lupus erythematosus, cardiovascular disease). It should be noted that the freedom from estrogen effects, although likely, is presumptive. Substantial data, e.g. on associations with vascular disease, blood pressure, and cancer, are not available because relatively little numbers have chosen to use this method of contraception. On the other hand, it is very logical to conclude that any of the progestin effects associated with the combination oral contraceptives can be related to the minipill according to a dose-response curve; all effects should be reduced.

No impact can be measured on the coagulation system. The minipill can probably be used in women with previous episodes of thrombosis, but the package insert in the United States carries the same precautions and warnings that combined oral contraceptives carry. This is not appropriate in view of the absence of estrogen and the littleer dose of progestin. Theoretically, minipills should be free of serious complications. Unfortunately, the package insert injects an element of medical-legal risk for the clinician.

The minipill is a good alternative for the occasional woman who reports diminished libido on combination oral contraceptives, presumably due to decreased androgen levels. The minipill should also be considered for the several patients who report minor side effects (gastrointestinal upset, breast tenderness, headaches) of such a degree that the combination oral contraceptive is not acceptable.

Do the noncontraceptive benefits associated with combination oral contraception apply to the minipill? Studies are unable to help us with this issue, again because of relatively little numbers of users. However, the progestin impact on cervical mucus, endometrium, and ovulation leads one to think the benefits will be present, but probably at a reduced level.

Good efficacy with the minipill requires regularity, taking the pill at the same time each day. There is less room for forgetting, and therefore the minipill is probably not a good choice for the noncompulsive, disorganized woman or for the average adolescent.