If you are unable to carry a pregnancy to full term everytime and have a history of miscarriages in your pregnancy record, it is important that you consult a doctor before planning another pregnancy. Miscarriages, one after another may be due to several reasons, most of which can be treated. Get prompt medical advice so that the doctor can perform tests and identify the source of the string of miscarriages.
There is little point in trying to conceive before the results of your tests are back. Once the problem has been identified, you can be treated accordingly. Start trying to conceive again on the doctor's advice and hopefully, you will have a successful pregnancy this time.