why does the iud cause spotting for the first month
If you have the Mirena IUD, then spotting between you periods is a normal occurrence. This occurs because the Mirena IUD contains a progesterone like hormone called levonorgestrel. This hormone has the effect of preventing pregnancy, and reducing the heaviness of your period. In the first few months of having the IUC, spotting between periods is very common. If you have a copper IUD, the frequency and character of periods should not be effected. The exception to this rule is that some women report more cramping during there period.