Risk factors for gestational trophoblastic neoplasia.

A case-control study to determine the gynecologic and reproductive risk factors for gestational trophoblastic neoplasia was conducted in the Baltimore Metropolitan Area. All cases (N = 190) that were pathologically diagnosed from 1975 to 1982 as hydatidiform mole, invasive mole, or choriocarcinoma were ascertained. Slides were independently reviewed by two pathologists. Cases were matched by age, race, and last menstrual period to controls who were delivered of normal pregnancies at term. In the analysis of medical record and interview data, factors found to be positively associated with gestational trophoblastic neoplasia included professional occupations (odds ratio = 2.56, p less than 0.0001), prior spontaneous abortions (odds ratio = 2.32, p = 0.02), and the mean number of months from the last pregnancy to the index pregnancy (cases = 35.9, controls = 28.2; p = 0.03). Factors found not to be associated with disease included contraceptive history, irradiation, ABO blood group, and smoking factors of the male partner. The findings suggest that gestational trophoblastic neoplasia may be part of a continuum of early (first-trimester) reproductive abnormalities.