Testing is generally a good idea for what doctors define as recurrent miscarriages.
For women between 25 and 35, a recurrent miscarriage is defined as three or more miscarriages in a row and for those younger than 25 or older than 35, two or more miscarriages in a row.
Meanwhile, while you're trying to conceive, there are some things you can do to improve your chances of having a healthy baby: Lead a healthy lifestyle, eat a well-balanced diet, don't smoke, don't take drugs, and drink less than three cups of coffee per day.