1. How big is the belly at 19 weeks of pregnancy? At 19 weeks of pregnancy, the belly has begun to protrude significantly, but the size varies from person to person. Generally speaking, the belly of a first-time mother will be smaller, while that of a mother with multiple children will be more obvious. At this time, the fetus has grown to about 15 centimeters and weighs about 240 grams. 2. Things to note during pregnancy: 19 weeks of pregnancy is a relatively stable period in pregnancy, but you also need to pay attention to the following matters: 1.