Is it dangerous for a person having 30% heart pumping power? If yes, then how can it be cured?

You can listen as well as you can see your baby's heart beat in your first TVS scan(Transvaginal Scan) at the sixth week with the help of  a Doppler at your doctor's appointment. Normally a baby's heart start to beat at six weeks. In any case, if you miss your TVS done in the early days of your preg....

Did your wife undergo heart valve surgery yet? Ovarian cyst removal is done laparoscopically and so is not meant to have much load on the heart. The ejection fraction of the heart is the function that is more importantly looked at before any operative procedure is advised/planned.

please get a blood test done for your son to rule out rheumatic heart disease.