When Your Belly Starts to Grow During Pregnancy: Factors Influencing Its Appearance

The transformations that a woman’s body undergoes during pregnancy involve not only internal restructuring, but also manifest in external changes, which from a certain time become noticeable to others. The main one among them is the growth of the belly during gestation. 

The rate of belly growth during pregnancy is individual for every woman. Some women cannot fit into their usual clothes by the 10th to 12th week, while others look like they’ve just overeaten, even in the third trimester. However, by knowing how the belly grows during pregnancy week by week, a future mom can plan her attendance at important events or trips and take care of updating her wardrobe with more comfortable clothing in advance.

When does a pregnant belly start to grow? 

If this is the first pregnancy, the belly usually starts to grow between 12 and 16 weeks, although initially, the increase will only be noticeable to the woman herself. Then the figure gradually changes, and by the 4th month, it is quite possible to gain a couple of kilograms. The second and subsequent pregnancies will show earlier, as by 8-10 weeks, the growth of the belly during pregnancy may require purchasing new clothing. 

This situation is completely normal, as previous pregnancies have left the muscles of the uterus and abdomen slightly stretched, allowing them to adapt more quickly to the new condition. Therefore, there is no strictly defined time when the belly will become noticeable to others. Moreover, there are known cases where an existing and properly developing pregnancy was hidden and did not accompany with noticeable roundness at all up until its peak and successful delivery. 

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Even though belly growth is a personalized process for every woman, there are average norms for how the belly grows during pregnancy. It is considered normal if the circumference of a future mother’s belly increases at a rate of about 2-3 cm every 2 weeks. 

Experts believe that the size of a pregnant woman’s belly should correspond to the indicators reflected in the table according to the current week of gestation:

Gestation week	Circumference (cm)
20	70-75
22	72-78
24	75-80
26	77-82
28	80-85
30	82-87
32	85-90
34	87-92
35	90-95
38	92-98
40	95-100

It is preferable that measurements are carried out by a specialist using the same measuring tape, as self-measurements usually result in significant inaccuracies. Although it may seem as though there should be no difficulty in taking measurements, there are rules, the violation of which leads to incorrect readings.

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After determining at which month of pregnancy the belly starts to grow, a woman should ensure that its size remains within the normal range corresponding to the gestation period. This means the belly can be either too small or, conversely, very large. Each situation has its own reasons. 

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• fetoplacental insufficiency;
• intrauterine infection;
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• premature aging or a thin placenta;
• post-term pregnancy;
• severe preeclampsia leading to fetal growth retardation.

However, a small belly can also occur if the pregnancy is normal. This can happen when the due date is incorrectly determined, as well as with a wide pelvis, where the belly is not so noticeable, being slightly “embedded.”

Deviation from the Norm: Too Large Belly

If the growth of the belly during pregnancy deviates from the normative characteristics towards enlargement, the causes of this phenomenon may include:

• uncontrolled weight gain with an excess of high-calorie foods in the diet;
• multiple pregnancy;
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• transverse or diagonal position of the baby in the womb;
• swollen and thick placenta (in case of Rh incompatibility);
• large size of the future baby;
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• narrow pelvis of the woman, when the baby is positioned higher.

The procedure for determining whether the belly size corresponds to established norms allows monitoring the normal progress of pregnancy. In the case of significant discrepancy with the norms, an additional ultrasound examination is prescribed.

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Apart from which pregnancy it is for a woman, several reasons can influence the earlier growth of the belly during pregnancy:

• carrying twins or triplets – in this case, the belly will generally be larger than with a single child, and will visually start to grow earlier;
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• lack of abdominal muscle tone – an untrained abdomen stretches more easily, which is why some mothers who haven’t exercised start to look pregnant earlier than others;
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• rapid growth of the fetus.

If changes don’t appear for a long time

The growth of the belly during pregnancy can not only surpass the average established timelines, but the enlargement can also occur significantly delayed not only in the early stages, but also in the second, and even third trimesters. If in the first trimester such visual changes are associated with the individual characteristics of a particular woman’s body, the belly growth during pregnancy by trimester subsequently becomes an important indicator of her normal development.

If a woman’s belly is not visible for a long time, both in the early stages and at the expected times, it may be due to:

• the woman’s constitution – larger women can conceal their ‘interesting’ condition longer;
• the presence of a tilted uterus – with this physiological feature, the uterus is inclined backwards towards the rectum, making its enlargement noticeable later;
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What Causes Changes in Body Shape

The growth of the belly during pregnancy is a process that follows a natural algorithm rather than occurring chaotically. Changes in the body shape of an expectant mother and the development of her belly are influenced by several factors, including the growth of the fetus, placenta, an increase in amniotic fluid volume, and active weight gain by the future mom herself. Inheritance also plays a significant role in how actively the belly grows during pregnancy. 

It is important to consider the belly sizes during pregnancy of close female relatives, like the mother and grandmother. The body becomes more rounded also because fat deposits start to appear on the belly. The growth progresses gradually, reaching its peak in the third trimester when it generally becomes difficult to hide the “interesting” condition, even if one tries very hard.

Shape of the Belly

The growth of the belly during pregnancy occurs alongside changes in its shape. In the past, before the advent of ultrasound, people used to determine whether a woman was having a boy or a girl based on whether her belly was round or pointed. The myth suggested that a woman with a pointed belly would have a boy, and a woman with a round belly would have a girl. However, these signs rarely matched reality. In fact, attention should be paid to the shape of the belly for completely different reasons – in terms of monitoring the normal development of the fetus. 
Even if the growth of the belly during pregnancy occurs according to established sizes, a shape, for example, like an oval lying on its side before delivery, may indicate a transverse position of the fetus. If asymmetry in the shape is observed, it’s necessary to check the development of the fetus, especially the size of its head.