Brief answer....given below
Detailed answer...
Hello,
Thanks for the query.
Around 80% of miscarriages occur in first 13 weeks of
pregnancy and are in general due to some chromosomal or placental problems and not because of any health problems of mother or father.
A probable cause in you can be your age also.
Around 30% miscarriages can occur in females who conceive above the age of 35 years,
However in some the causes can be due to obesity,overuse of alcohol,
smoking,caffeine etc,use of illegal drugs,some underlying conditions like
diabetes,underactive or over active
thyroid,HIV,some kidney ailment,
high blood pressure,use of some medicines etc.
You need to consult your doctor and get blood tests and some genetic tests done so as to arrive at the diagnosis of cause.
I hope it helps,however you may revert to me for any further query.
Best of luck
Thanks