Kids having kids' is an apt description. And it's distressing that one in five pregnant teen will have to experience a miscarriage. But not all miscarriages have to happen. Educate yourself if you're pregnant. Knowledge is power.
Several drugs can cause abnormalities in the unborn child.
Alcohol is also known to cause abnormalities in the fetus and may induce miscarriages. Lastly, smoking causes the fetus to grow less well than fetuses whose mothers don't smoke. Stop smoking both before conception and during pregnancy. Normal exercise is fine and it's safe to continue your usual forms of activity. But please avoid strenuous physical exercise and movements.