After a miscarriage, what should be paid attention to before and after pregnancy?

Patient's question:

: Doctor, hello
In 2012, I had a benign tumor in my left kidney, which was removed. In September 2014, I became pregnant, but after two and a half months, I experienced vaginal bleeding. An ultrasound showed no fetal heartbeat, and the doctor diagnosed it as a missed miscarriage. I then underwent a miscarriage procedure. The doctor also couldn’t explain why this happened. Additionally, I am now 30 years old and very eager to have a child. I would like to consult about why I experienced a missed miscarriage, what I should pay attention to before and after pregnancy, whether it will affect future pregnancies, and what I should do.
Regarding the missed miscarriage, if I am currently

Doctor's answer:

Miscarriage due to fetal death without expulsion, prolonged retention in the uterine cavity, can lead to maternal coagulation dysfunction, making it difficult to stop bleeding. Severe cases may result in shock or even death. The main cause is placenta adhesion to the uterine wall, which is difficult to separate. In the future, pay attention to strengthening nutrition before and after pregnancy, avoid smoking and alcohol, and moderate sexual activity. Pre-pregnancy, undergo the six-item pre-natal screening.