Bleeding first trimester with cramping. Baby heartbeat seems to be normal. Last pregnancy ended in stillbirth at 20 weeks 1 day, placenta fell apart. What can I do to minimize risk? 2.7 cm tear this time last pregnancy it increased from 4.4 - 8.6cm

High risk. You are a high risk pregnancy. You need to stay in touch with your doctor and you need an ob/gyn that specializes in these high risk pregnancies .
Obgyn care. The first step is to find an Obgyn who can provide your care and help guide you through the pregnancy. They should investigate in more detail the issues surrounding the 20 week loss to see if anything different needs to be done this time. They can also monitor the subchorionic hematoma that is present now. If needed they can refer you to a perinatologist for more guidance.