Sometimes pregnant women feel that their belly is expanding by leaps and bounds or vice versa that it is completely unnoticeable. The belly height usually corresponds to the term of pregnancy. For example, for the 32th week of pregnancy it should be equal to 32-33 cm. At the same time belly’s completeness depends on individual women’s characteristics. Nevertheless there are quite reasonable questions why and how does it growth? The belly is expanding because a baby is growing in it and it is happening similar to each future mother.

What is reason of the belly expansion during pregnancy? It happens due to fetus, uterus growth and increase the amount of amniotic fluid- the future baby habit.

The dimension of fetus is possible to determine by means of ultrasound investigation. By means of transvaginal investigation it is possible to discover a fetus after 2-3 weeks of development. The diameter of fetal egg for this term is 2-4 mm.

Uterus dimension expansion is within the whole period of pregnancy. During first some weeks a uterus is similar to pears. By the end of the second month of pregnancy its dimension is increasing approximately in three times and it has rounded shape. During the next half of pregnancy it keeps its rounded shape, but on third trimester it takes an egg form. Before pregnancy a uterus weight is 50-100g but by the end of pregnancy it is 1000g. During pregnancy each muscle fiber lengthens in 10 times and thickens in about 5 times.

The amniotic fluid volume increase is irregular. Thus, during 10 weeks of pregnancy it is about 30 ml, at 13-14 weeks it is 100 ml, at 18 weeks it is 400 ml. The maximum volume is noticeable to 37-38 weeks. By the end of pregnancy the amniotic fluid volume may decrease to 800ml.

The rate of uterus increase the same as belly expansion should quite strictly corresponds to above mentioned parameters because these are essential characteristics of normal pregnancy. In the early period when the uterus is not observed through the front abdominal wall, the inadequacy of its size to the probable date of pregnancy may signifies about ectopic pregnancy, when fetal egg usually develops in the fallopian tube.

The excess of presupposed dimension is typical to chorionepithelioma. It is a swelling which develops through placental tissue and presents quite great amount of small bubbles. During this problem the fetus dies, but to save mother’s health it is necessary timely treatment.