My wife is 2months and 8days pregnant but growth of baby is not enough is it serius problem?

Sometimes. Sometimes the date of the last period is uncertain so it is difficult to determine how far along a pregnancy is. Other times the fetus is not in a position that allows an accurate measurement. In rare cases there can be a problem that restricts growth of a fetus, but that is less common in the first trimester. A second ultrasound a couple of weeks after the first will help the OB know more to say.