No – you can have the IUS inserted any time during your menstrual cycle if you are already on contraception and you are not pregnant. Some doctors prefer to insert a first IUS during the menstrual cycle simply as a means to ensure that the woman is not already pregnant. Although most women cringe at the idea of visiting the gynaecologist during their menstrual period it makes for an easier insertion as the cervical opening is open, softer and lubricated from the menstrual bleeding. Replacing a device can be done at any time of the cycle.