Thanks for writing in.Pregnancy
and child birth are a stress on the abdominal wall. At the same time this gets resolved with time and now after five months, your abdominal wall should have got back to normal. You have not writes if your childbirth was caesarean section
or normal vaginal delivery
If it was caesarean section then you might have to get the scar examined by your doctor for any healing disturbances. A ultrasound
scan will confirm any problems.
Regarding your run, please go for smaller runs and get your system adapted before you take a longer run.
Hope this helps.