RESUMO
A retrospective case-control study was conducted to investigate the risk of twinning following oral contraceptive (OC) use. A total of 157 women with twin deliveries were included from two major hospitals located in Cairo. Two controls selected from women with singletone deliveries were matched to each case of twin delivery on basis of maternal age and parity. Information on (OC) use prior to last pregnancy and date of last menstrual period was provided by interviewing the study women. Potential biases in the study design were discussed. The overall (OC) use prior to the last pregnancy was significantly higher in twin group in comparison with the controls (P < 0.05). The study provides an evidence of increased risk of twinning among conceptions occurring within less than 3 months from cessation of (OC) use (OR = 2.3, 95% confidence limits: 1.2 - 4.4).