Short birth intervals and uterine cervical cancer risk in Jamaican women

Abstract

High parity common in developing countries has been consistently associated with higher cervical cancer (CC) risk. Pregnancy-related immunosuppression has been proposed as a possible mechanism by which oncogenic human papillomavirus (HPV) can replicate. Stanczuck reported a higher risk of CC among women genetically predisposed to lower immune response. In-vitro studies also demonstrate increased transcriptional activity of HPV16/18 in a progesterone-rich environment. Indeed a greater than 2-fold increase in CC risk was reported in women with rapid multiple births. However this study used nulliparous women as referents which does not allow one to distinguish the role of parity from that of birth-intervals. Birth-intervals are a modifiable risk factor of CC 80% of which occurs in developing countries. To determine whether short birth-intervals increase CC risk incident cases were identified through the Kingston-St. Andrews Jamaica Cancer Registry and controls were identified from cytology log-books of facilities where cases were diagnosed. Response rates of cases and controls were 82% and 60% respectively. Analyses are restricted to 183 cases and 214 controls with >/= 2 pregnancies each lasting >/= 7 months (>/=1 birth interval). The average interval was estimated by dividing the sum of non-pregnant months by total pregnancies. We assessed factors known to be associated with CC or pregnancy for confounding and retained those that changed the OR >/= 10%. (excerpt)