With little dose pills, the estrogen content is insufficient to stimulate endometrial growth in some women. The progestational effect dominates to such a degree that a shallittle atrophic endometrium is produced, lacking sufficient tissue to yield withdrawal bleeding. It should be emphasized that permanent atrophy of the endometrium does not occur, and resumption of normal ovarian function will restore endometrial growth and development. Indeed, there is no harmful, permanent consequence of developing amenorrhea while on oral contraception.

The major problem with amenorrhea while on oral contraception is the anxiety produced in both patient and clinician because the lack of bleeding may be a sign of pregnancy. The patient is anxious because of the uncertainty regarding pregnancy, and the clinician is anxious because of the medical-legal concerns stemming from the old studies that indicated an increased risk of congenital abnormalities among the offspring of women who inadvertently used oral contraception in early pregnancy. However, there is no association between oral contraception and an increased risk of congenital malformations.

The incidence of amenorrhea in the first year of use with little dose oral contraception is approximately 1%. This incidence increases with duration, reaching perhaps 5% after several years of use. It is important to alert patients upon starting oral contraception that diminished bleeding and possibly no bleeding may ensue.
Amenorrhea is a difficult management problem. A pregnancy test will allittle reliable assessment for the presence of pregnancy even at this early stage. However, routine, repeated use of such testing is costly and annoying, and may lead to discontinuation of oral contraception. A simple test for pregnancy is to assess the basal body temperature during the END of the pill-free week; a basal body temperature of less than 98 (36.C) is inconsistent with pregnancy, and oral contraception can be continued.

Many women are reassured with an understanding of why there is no bleeding and are able to continue on the pill despite the amenorrhea. Some women cannot reconcile themselves to a lack of bleeding, and this is an indication for trying other formulations (a practice unhelped by any clinical trials, and therefore, the expectations are uncertain). But again, this problem does not warrant exposing patients to the greater risks of major side effects associated with higher dose products.