It is impossible to predict exactly when it will begin to grow, but in the early stages, waist size practically does not change. However, each new gram of embryo stretches the uterus, as a result both it and the tummy increase.
After the test showed 2 stripes, the volume of the uterus does not exceed 5 ml with a weight of 50-60 g. But at about 5 weeks of pregnancy, it begins to grow, and a gradual but systematic development of new muscle fibers occurs. After all, the uterus will have to stretch almost 500 times relative to its original size.
At 9 weeks of pregnancy, the uterus becomes the size of a goose egg. As long as it fits within the boundaries of the small pelvis, the stomach does not grow. Next, the uterus grows and rises above the level of the pelvis, heading into the abdominal cavity.
At this time, the waist also begins to slowly expand, and after 14-15 weeks you can measure the height of the fundus of the uterus. It is its wide part - the bottom - that rises into the abdominal cavity and determines the circumference of the abdomen during pregnancy week by week.
After 16 weeks, the belly increases significantly and in most women becomes noticeable. The growth rate of the tummy by week depends on the body build, the size of the small pelvis, the number and weight of the fetuses.
The abdominal circumference (AC) of a pregnant woman is a purely individual indicator, since initially each woman’s waist circumference is different. The height of the uterine fundus more accurately reflects the size of the fetus by week of pregnancy, so the doctor measures both parameters.