Ectopic pregnancy: a case-control study of aetiological risk factors.

Aetiological risk factors for ectopic pregnancies were evaluated in a prospective study of 86 consecutive patients with ectopic pregnancy and two age- and parity-matched control groups of women in normal early pregnancy; those with planned pregnancy (65 pairs) and those having legal abortion (51 pairs). Compared with women with planned pregnancy, the patients with ectopic pregnancy more often had an IUD in situ, they had less frequently used hormonal contraception, and they had more legal abortions, curettages, previous ectopic pregnancies, gynaecological operations and salpingo-oophoritis. Compared with women having legal abortion, the patients with ectopic pregnancy had favoured IUD-usage, or they had been without any contraception, and they had an increased frequency of previous ectopic pregnancies. The frequency of fertility problems was also increased in patients with ectopic pregnancy. Our results show that gynaecological pelvic operations, endometrial curettage and evacuation, gynaecological infections, and usage of IUD are important risk factors for ectopic pregnancy, and that infertility seems to be a sign of this risk. In addition, the clinical characteristics of the patients with ectopic pregnancy were similar to those of the patients having legal abortion.