When a woman has three or more miscarriages in a row. It is relatively common to have one or two miscarriages.
It can occur for many reasons such as blood disorders and auto immune disorders such as Lupus.
This involves many investigations including blood tests and ultrasounds.
Unfortunately, you cannot prevent it.
However, there are many things that can be used to treat it.
Not at all. There are many things that can contribute to miscarriage and each situation must be assessed individually.