TABLE 4-1 Well-established Major Protective Effects of Oral Contraceptives (OC) by Problem or Condition, United Kingdom or United States

 

Relative Risk

   

Problem or Condition Protected Against

Current Use

Past Use

Influenced by Duration of Use

Influenced by OC Formulation

Menstrual problems a

0.75

1.0

No

Yes—protection decreases with “low-dose” pills

Iron-deficiency anemia a

0.75

1.0

No

Unknown

Benign breast cysts a

0.5

1.0

Yes—protection increases as duration increases

Yes—protection increases as progestin increases

Pelvic inflammatory disease a

0.5

1.0

Unknown

Unknown

Functional ovarian cysts a

0.25

1.0

No

Probably not

Epithelial ovarian cancer b

0.5

0.5

Yes—protection increases as duration increases

Probably not

Endometrial cancer b

0.5

0.5

Yes—protection increases as duration increases

Probably not

a Based on hospital admissions data.

b Based on incidence data.

SOURCE: Adapted from M. P. Vessey, "The Jephcott Lecture, 1989: AnOverview of the Benefits and Risks of Combined Oral Contraceptives,"in Oral Contraceptives and Breast Cancer, R. D. Mann, ed. (Park Ridge, N.J.: The Parthenon Publishing Group,1990).

reducing hospital admissions for problems related to menorrhagia. Evidence also indicates that the risk of pelvic inflammation decreases in women taking the pill. (Some recent work suggests, however, that the pill is associated with an increased risk of chlamydial infection, although a clear association has not been established in a prospective study.) Use of the pill is associated with decreased risk of ovarian tumors, both benign and malignant; in addition, the risk of endometrial carcinoma begins to decline after one year of oral contraceptive use. Protection against ovarian and endometrial malignancy is greatest in nulliparous women. The risk of ectopic pregnancy and its adverse effects on reproductive health are also decreased in pill users (because most oral contraceptives prevent ovulation, which, of course, precludes pregnancy, ectopic or otherwise).



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