The prevalence of abnormal cervical cytology in a group of New Zealand women using contraception: a preliminary report. The New Zealand Contraception and Health Study Group.

Between 1980 and 1986, cervical smears were obtained from 9430 women throughout New Zealand to determine their eligibility to enter the New Zealand contraception and health study. Excluded were 128 women in whom the smear was unsatisfactory or the cytological diagnosis was inconclusive. The prevalence of mild dysplasia or worse was 4.3% and of carcinoma in situ/invasive carcinoma was 0.5%. Risk factors that were identified were age at first intercourse, number of sexual partners, age and smoking. Over the age range studied (essentially 20-39), the prevalence of dysplasia decreased slightly with increasing age but the prevalence of carcinoma in situ/invasive cancer increased from 0.18% at ages 20-24 to 0.74% at ages 35-39.