Pregnant belly stages: How your belly grows week by week

A photo containing three picture of a woman with pregnant belly showing the growth progress.
  • Updated Dec 24, 2024
  • Published

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Created with Nataliia Yermolovych, MD, Obstetrician-Gynecologist

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In a nutshell

The pregnant belly appears like a bump during the first trimester, as your baby is only about the size of a poppy seed in the first 4–8 weeks. So, pregnancy and belly growth may not be noticeable.

Your belly may start to become visible after the 12th week (2nd trimester) of pregnancy as your uterus grows and the baby maintains a shape. As the pregnancy progresses and reaches the third trimester (28–40 weeks), there is rapid and noticeable belly growth, because the baby reaches its full size, and the uterus and amniotic fluid fully expands to support the baby.

It is important to note that belly growth widely varies from woman to woman, as every pregnancy is unique and depends on many factors, like the baby’s size and position; mother’s weight, height and body physique; single or twin pregnancy; and more.

Did you know that a growing pregnant belly is a visible sign of your baby’s development and the progress of your pregnancy? Belly growth during pregnancy is a source of excitement for all expecting mothers, but it is important to remember that every pregnancy and female body is unique. Hence, belly size and shape can vary widely. 

Let’s discuss the pregnancy belly stages in detail and what you should expect in each week and trimester of your pregnancy.

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Pregnant belly: What to expect during pregnancy

A pregnant belly typically grows as your uterus enlarges and expands to accommodate your growing baby. However, the growth of your belly during pregnancy depends on many factors, including: 

  • Your body type and tendencies. These are based on genetics, metabolism, physical activity, and dietary habits.
  • Your baby’s size: Some babies are born healthier and bigger, while some are comparatively skinnier and smaller, which is normal. 
  • History of your previous pregnancies.

Pregnant belly stages: Week-by-week changes

Here is an overview of belly growth during each trimester of pregnancy:

First-trimester pregnancy belly week-by-week insights

So, what should your week-by-week pregnant belly look like? Let’s find out. 

During the first trimester of your pregnancy, it’s normal to have no visible belly growth, as the uterus and baby are still small and tucked inside the pelvis. 

You may experience a puffed-out appearance of your belly in the first trimester due to hormonal changes, which can cause constipation, bloating, and a small bump. 

Week 1–4: During the first two to four weeks of pregnancy, your uterus continues to thicken to support your baby, and you may not even realize by the appearance of your tummy that you are pregnant. From the fourth week, your baby will be about the size of a poppy seed.

Week 5–8: During the fifth to eighth weeks of the first trimester, your uterus starts to expand, and your baby’s organs begin to develop and function. You may experience a sense of fullness or bloating due to hormone-related fluid retention.

Week 9–12: By 9 to 12 weeks of pregnancy, your uterus expands to the size of a grapefruit, and your baby grows faster every day. You may notice a small bump or slight rounding of the abdomen during or at the end of the 12th week, especially if it’s your second or third pregnancy.

👉Find out more: First-trimester screening: Understanding genetic testing and results during early pregnancy

Second-trimester pregnancy belly

In the second trimester, or the 13th to 27th week of pregnancy, the fetus continues to develop. As the uterus stretches and rises above the pelvis, belly growth becomes visible. The fetus’s facial features, fingers, and toes become well-defined, and you may start feeling fetal movement as the second trimester progresses. 

Week 13–14: In the 13–14th week of pregnancy, a small bump will become visible in your belly, and more blood will be pumping towards your pelvic area to nourish the growing baby. This may increase your sex drive and urge to urinate.

Week 15–16: During the 15–16th week of pregnancy, your belly growth will become more prominent, and your baby will grow to the size of an orange. More and more blood will be flowing towards your pelvic area, which may also cause your body to produce more milky fluid from the vagina. 

Make sure to consult your doctor if the vaginal discharge smells bad—for example, if it smells strongly like fish or looks like cottage cheese, or if you experience pain and itching in the discharge.

Week 17–18: By week 18, you may sense your baby’s first movement, which can feel like a gentle fluttering or bubbling sensation. Your belly will become a bit round, and your baby will be around the size of a bell pepper or a cucumber.

Week 19–20: During the 19–20th week, your baby will be around 15.3 cm long, which is approximately the size of a beef tomato. You will start noticing a rounder belly.

Week 21–22: By the 21st week, your belly will become big enough to look pregnant, and your clothes may become tighter. Your baby will be the size of a carrot or a sweet potato.

Week 23–24: During the 23rd–24th week of pregnancy, you may notice stretch marks on your belly. As your baby grows larger, skin stretches, and your uterus extends above the navel. During this time, your baby is about the size of a large mango.

Week 25–26: By the 25–26th week, your belly will look quite large and noticeable, and the baby will have grown to the size of a large pineapple.

Week 27: By the 27th week, you will gain some extra weight, and you may feel more bloated and constipated due to the higher release of progesterone hormone and squeezing of the stomach by the baby.

Third-trimester pregnancy belly

By the third trimester or the 28th week of pregnancy, the fetus grows both in size and weight and becomes more than 270 millimetres long, which is roughly the size of an eggplant. It begins to position itself head down, and your pregnant belly becomes prominent and starts to reach its full size.

An infographic showing a baby size chart during pregnancy

When does your stomach start growing during pregnancy?

So, when does your stomach start growing during pregnancy? Typically, your stomach will begin developing and show a visible bump by the early second trimester or between 12 and 16 weeks. 

However, it is important to remember that the timeline of belly growth can vary widely from woman to woman, depending on factors like their body tendency, baby size, and whether they are carrying twins. 

Carrying twins or multiples can cause a bump or belly growth to appear earlier. A bump in twin pregnancy can show as early as six to eight weeks, as there is more bloating and larger uterus growth to accommodate twins.

👉Find out more: Safe and comfortable sex positions during pregnancy: A guide for couples

Belly growth during pregnancy: What affects it?

Other factors that can affect belly growth during pregnancy include:

1. Previous pregnancies

Your muscles and ligaments might become loose and flexible if you have experienced pregnancy before, which may cause your pregnant belly to show up earlier in your next pregnancy.

2. Amniotic fluid levels

Amniotic fluid is a clear, watery liquid produced by the placenta and the fetus’ kidney to surround and protect the baby. As the baby grows and the uterus stretches, the amniotic fluid increases, causing your belly to appear bigger. 

The levels of amniotic fluid can affect your belly growth, and several factors can influence amniotic fluid levels, like your baby’s growth rate, maternal health and pregnancy stage, and whether you are carrying multiples, which can increase amniotic fluid and cause the belly to appear bigger.

3. Baby size and position

Another factor that can affect the growth of your pregnant belly is your baby’s size and how it positions itself. Your baby’s position can make your belly appear low, high, rounded, pointed, or wide. 

For example, if your baby is facing forward and towards your abdomen, it can cause your belly to appear more rounded and prominent. If your baby faces backwards and towards your spine, your belly can appear flattened and broader.

4. Maternal weight and height

Shorter height or more weight gain during pregnancy can cause a woman’s belly to appear more rounded and prominent. Similarly, taller or skinnier mothers may have a longer torso, making their belly more spread out.

You can try our pregnancy weight gain calculator to check your pregnancy health and well-being or understand your weight gain based on your age and height.

5. Food

Eating large meals can also cause a mother’s pregnant belly to appear bigger than ones who have less appetite during pregnancy.

Why is my pregnant belly sometimes hard and sometimes soft?

Let’s consider an example. Even without pregnancy, our stomach seems harder at times and softer at other times. We can understand that this condition is normal and happens as a result of normal digestive processes, indigestion, and eating habits. 

Similarly, during pregnancy, our body goes through numerous physical changes and digestive processes, regulating the functioning of two living beings simultaneously. In such conditions, changes in the pregnant belly are normal and can happen due to various reasons, like: 

  • Digestion and bloating: If you experience bloating or indigestion during pregnancy, you may feel a tight, hard, and painful stomach.
  • Baby’s movement and positioning: After the 30th week of pregnancy, the baby’s movement typically increases to at least 10 times or more per day. Your baby’s movement and positioning can also make your belly feel hard in some places and soft in others.
  • Braxton-hicks contractions: Braxton-hicks contractions, also known as false labor, occur when the uterine muscles contract and relax. This commonly occurs after the sixth week of pregnancy and helps tone the uterine muscles to prepare them for labor. These temporary uterine contractions may cause your stomach to feel hard during the contractions and soft as it relaxes or after the contractions and relaxations are over.

When does your stomach start to get hard during pregnancy?

Your stomach will start to get hard during the second trimester or about 12–16 weeks into pregnancy, as the uterus grows bigger and the baby’s body comes into a proper shape. However, the firmness of your stomach during pregnancy depends on your baby’s position and body type.

Pregnancy belly concerns: when to talk to a doctor

You should talk to your doctor if: 

  • Your belly growth seems excessively slow even after the first trimester, or abnormally fast.
  • You experience sharp, sudden, and severe cramp-like pain or discomfort.
  • You experience heavy bleeding or bleeding with abdominal cramps.
  • You feel contractions before your 37th week that happen again within 10 minutes.
  • You have any concerns about preterm labor or experience unusual pregnancy signs.
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Questions from the Femia community

  • Can my belly shape indicate my baby’s gender?

    No, your belly shape doesn't indicate your baby's gender. Belly shape appears based on factors like maternal body type, weight gain and physique, pregnancy stage, and baby's size and position.

  • Why does my belly feel tight at night?

    Your belly may feel tight at night due to slowed digestion or temporary uterine contractions. Both conditions are normal.

  • Is it normal to have stretch marks on my belly during pregnancy? How to deal with them?

    Yes, stretch marks on the belly are normal, and they arise as the skin on your abdomen stretches during pregnancy. They gradually fade with time after your baby is born and become less noticeable, but there is no permanent solution or treatment for removing stretch marks. You can moisturize the area to soothe or reduce it.

The bottom line

Pregnant belly stages and growth are an exciting part of pregnancy that can help you understand how your baby is developing. Still, it can vary widely from woman to woman depending on several factors, like maternal weight and body physique, the baby’s size and how they position themselves, pregnancy stage, previous pregnancies, genetics, and more. 

Hence, it is essential to enjoy your journey, focus on healthy habits, and avoid comparing yourself to others, as every pregnancy is unique. If you experience anything unusual, like abnormally slow or fast belly growth, severe abdominal pain or cramps, bleeding, or are concerned about your belly growth, it is recommended to consult your healthcare provider for personalized advice.

Moreover, remember that belly growth during pregnancy mostly starts after the second trimester; before that, you may or may not notice a bump, which is normal.

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