The most common cause for miscarriage is a chromosomal defect with the fetus. It is believed that up to 70% of miscarriages are caused by this reason. This does not mean there is something wrong with the parents' ability to produce a child. Rather, there was something wrong with that one particular egg or sperm that caused the embryo to not develop or implant properly.

Are there any other causes of miscarriage aside from chromosomal defect?

I read somewhere that the increased and prolonged use of hormonal birthcontrol was contributing to the higher percentage of miscarriages today.

In my mother's time, miscarriages were few and far between. Today, I think most of the people I know have had one.