In Denmark and in the Manchester cohort study, two populations with low parity, the effects are less visible for pre-neoplastic lesions (reviewed in [30]). It has been speculated that the general reduction in the average number of births in developed countries over the last decades may have contributed to the re- duction in cervical cancer incidence but formal proof of the hypothesis has not yet been produced. The combined effect in the risk of cervical cancer of parity and exposure to OCs has been examined and shown that at each level of OCs use there is an increased risk with a significant trend with the number of lifetime pregnancies.
1
—
—