Your waistline will expand because of the dramatic changes taking place inside of you. By the start of the forth month, the fetus will have grown to more than six inches in length, and it may weigh five ounces. The fetus will also be enclosed in fluid within the uterus, and the wall of the elastic uterus will grow thicker to contain this extra load. These changes will cause your abdomen to distend, and you may notice stretch marks – pink horizontal lines – on your stomach. Some people may recommend rubbing lotion, cold cream, oil on these marks. But the truth is there is not much you can do. You are either born to get them or not. You can however control your overall body weight by following your clinician’s orders about diet.