The effects of contraceptive methods on the quality and quantity of breast-milk.
Contraception is practiced by women following childbirth in order to prevent pregnancy temporarily or permanently. However, during the period of lactation, methods which exercise an adverse effect on the process and on the children should not be used. With steroidal contraceptives, the concern is the effect on the quantity and quality of breastmilk. The major problem in assessing quantity and quality lies in the difficulty of obtaining reliable assessment criteria. Those which are most commonly used are: mothers' impression on milk production, duration of breastfeeding, proportion of mothers who are able to breastfeed, need for supplementary feedings, infants' weight gain and growth curve, milk quantity (weighing child before and after feeding), milk quantity by breast pump, and milk composition. Combined and sequential pills were found, in 7 of 20 selected studies, to exercise no significant adverse effects on milk production. Of the 16 preparations which were found to have adverse effects on lactation, 4 were high dose combined pills not presently available, 10 were low-dose or average progestogens, and 1 was a low-dose preparation. 3 studies found milk suppression to be dose-dependent, with the higher dosage preparations having a more suppressive effect. Milk quantity was decreased by 0.5 mg chlormadinone acetate but other studies found that this microdose progestogen did not have an adverse effect on lactation. All studies using depomedroxyprogesterone acetate indicate no adverse or beneficial effects on milk production. Other longacting progestogens likewise showed no adverse effects. However, injectable estrogens did have a suppressive effect on breastmilk. Oral and injectable contraceptives presently available had little effect on milk composition. Milk immunoglobulin did not seem to be affected. The low-dose preparation levonorgestrel + ethinyl estradiol reduced milk volume dramatically from between 30-54%. Despite this, there was no difference in growth rates between the study groups. The IUD seemed to have no effect on milk quantity and quality. Although breastfeeding does have an effect on fertility control, contraceptive methods should be used by lactating women, especially those methods which exercise no adverse effect on lactation. It can be concluded that steroidal contraceptives have little or no effect on milk composition but that combined OCs and other steroidal contraceptives with estrogen may have an adverse effect on milk production.