Why Do I Feel Bubbles in My Stomach While Pregnant?

That bubbling, fizzing, or fluttering sensation in your stomach during pregnancy usually comes from one of two sources: digestive gas moving through sluggish intestines, or your baby’s earliest movements. In many cases it is both happening at once, which is why the feeling can be so hard to pin down. The hormonal shifts of pregnancy dramatically slow your digestive system, trapping more gas in your gut than usual, while fetal movements in the second trimester often start as faint pops and bubbles that feel almost identical to gas.

Progesterone and the Slowdown in Your Gut

The single biggest reason your digestive tract feels different during pregnancy is progesterone. This hormone, which rises steadily from the first weeks onward, directly relaxes the smooth muscle lining your intestines. Research shows that progesterone achieves this partly by boosting production of nitric oxide, a chemical that causes smooth muscle to relax, and partly by blocking the signaling pathways that normally tell those muscles to contract.¹ The result is that food moves through your system more slowly than it did before you were pregnant.

This slowdown is measurable. Studies tracking gastrointestinal transit time in pregnant women have found that the second and third trimesters bring a clear prolongation compared to the first trimester and the postpartum period. Because the effect reverses after delivery, researchers attribute it to hormones rather than to any lasting structural change.² When food lingers longer in your intestines, bacteria have more time to ferment it, and that fermentation produces gas. The gas collects in pockets along your bowel, and when it shifts or works its way through, you feel those telltale bubbles.

What the Bubbling Physically Is

Gas in the intestines is not a single event but a constant process. Your gut bacteria produce hydrogen, carbon dioxide, and small amounts of methane as they break down food. Normally, most of this gas gets absorbed through the intestinal wall or passed without you noticing. But when transit slows, two things change: more gas is produced because bacteria have longer to work, and the sluggish bowel does not move gas along as efficiently. Instead of flowing smoothly, gas pools in segments of the intestine and then shifts in bursts, creating the popping or bubbling sensation you feel.

Certain foods accelerate gas production. Beans, lentils, cruciferous vegetables like broccoli and cabbage, whole grains, and carbonated drinks are well-known culprits even outside of pregnancy. During pregnancy, your slower digestive system amplifies the effect. Many pregnant people also develop temporary lactose sensitivity because the sluggish gut changes how efficiently lactose is broken down, adding dairy to the list of potential gas triggers.

Swallowed air contributes too. Eating quickly, talking while eating, chewing gum, and drinking through a straw all introduce extra air into your stomach. Some of that air travels into the intestines rather than being belched out, and when it moves through your gut, it creates the same bubbly feeling.

When Bubbles Are Actually Your Baby

Between roughly 16 and 25 weeks, most people begin to feel their baby’s first movements, a milestone called quickening. The initial sensations are remarkably subtle. People commonly describe them as bubbles, flutters, a fish swimming, or gentle tapping. In a first pregnancy, these are easy to dismiss as gas because the feeling is genuinely similar, and many people do not recognize quickening for what it is until they have felt it consistently for a few weeks. In subsequent pregnancies, recognition tends to come earlier simply because you know what to look for.

There is no foolproof trick to distinguish fetal movement from gas in those early weeks, but a few patterns help. Gas bubbles tend to feel irregular and scattered around different parts of your abdomen, and they often accompany bloating, mild cramping, or the urge to pass gas. Fetal movement, once you get used to it, tends to recur in roughly the same spot, often low in the pelvis initially, and it is not accompanied by other digestive symptoms. Over the following weeks, the movements become stronger and more obviously kick-like, removing the ambiguity entirely.

How the Growing Uterus Compounds the Problem

Progesterone handles the chemical side of the digestive slowdown, but the physical side matters too. As the uterus expands through the second and third trimesters, it pushes the stomach, intestines, and other abdominal organs upward and to the sides. This compression reduces the space available for your bowel to expand and move gas along. The stomach itself gets crowded, which is why large meals become increasingly uncomfortable and why many people shift to smaller, more frequent meals as pregnancy progresses.

The mechanical pressure also changes the character of the sensations you feel. A pocket of gas that would have passed unremarkably through a non-compressed intestine can produce a more pronounced bubble or gurgle when the surrounding space is tight. Some people report that the bubbling becomes more noticeable when they change position, lie on one side, or wear clothing that presses on their abdomen. This is consistent with gas and fluid being redistributed under pressure.

Why Some People Feel More Than Others

Pregnant people vary widely in how intensely they perceive abdominal sensations, and several factors account for this. One is placental position. When the placenta attaches to the front wall of the uterus, called an anterior placenta, it acts as a cushion between the baby and your abdominal wall. Research has found that an anterior placenta is significantly associated with reduced perception of fetal movement.³ If you have an anterior placenta, the bubbles you feel are more likely to be gas than the baby, at least until the baby grows large enough for kicks to transmit through the placental cushion. This can delay the recognition of quickening by several weeks.

Body composition also plays a role. A thicker layer of abdominal tissue can muffle the subtler fetal movements, making gas sensations comparatively more prominent. First-time parents tend to perceive movement later and with less certainty than those who have been pregnant before, partly because the uterine muscle is firmer in a first pregnancy and partly because the sensation is entirely new.

Individual variation in gut bacteria matters as well. A prospective study of pregnant people found that those with greater microbial diversity in their gut experienced fewer bowel symptoms, while those with less diverse gut communities reported more bowel symptoms and more perceived stress.⁴ The connection between stress and gut symptoms during pregnancy is bidirectional: stress can worsen digestive discomfort, and persistent digestive discomfort can increase stress. This means that two people at the same gestational age, eating similar diets, can have meaningfully different experiences of abdominal bubbling.

Trimester-by-Trimester Pattern

The bubbling sensation follows a rough arc across pregnancy, though it varies from person to person. In the first trimester, digestive gas is the primary culprit. Progesterone levels are climbing but the uterus is still small, so mechanical compression is minimal. Nausea and food aversions may change what you eat, which in turn changes what your gut bacteria are fermenting. Many people notice increased bloating and gas from very early in pregnancy, sometimes before they even know they are pregnant.

The second trimester introduces the ambiguity discussed above. Gas continues, but fetal movements begin as well. This is the period when the question “is that gas or the baby?” comes up most often. By around 24 to 28 weeks, most people can clearly distinguish the two. The baby’s movements become rhythmic at times, and you may start to feel hiccups, which have a repetitive, pulsing quality nothing like a gas bubble.

In the third trimester, mechanical compression peaks. The uterus is at its largest, and the intestines are squeezed into less space. Gas-related bubbling can become more frequent and more noticeable. Fetal movements, meanwhile, shift in character: fewer dramatic kicks as the baby runs out of room, and more rolling, stretching, and pressing. Some people describe the late-pregnancy combination of gas and fetal movement as an almost constant internal activity, with different kinds of bubbles and shifts happening throughout the day.

Practical Ways to Reduce Gas-Related Bubbling

You cannot override progesterone’s effect on your gut, but you can reduce the amount of gas being produced and help it move through more efficiently.

Eat smaller meals: Spreading food across five or six smaller meals rather than three large ones gives your slowed digestive system less to handle at once and reduces the amount of gas generated per sitting.
Chew slowly: Eating more slowly cuts down on swallowed air and gives digestive enzymes a head start on breaking food down before it reaches the bacteria in your lower gut.
Move after eating: A short walk after a meal stimulates intestinal motility and helps gas pass rather than accumulate. Even 10 to 15 minutes makes a difference when your gut is sluggish.
Limit known gas producers: If beans, cabbage, onions, or carbonated drinks consistently make the bubbling worse, scale them back. You do not need to eliminate entire food groups, just pay attention to your own triggers and adjust.
Stay hydrated: Water helps keep things moving through your intestines. Dehydration, which is easier to slip into during pregnancy, worsens constipation and gas buildup.
Talk to your provider about supplements: Prenatal vitamins containing iron are a common contributor to constipation and gas. Your provider may be able to suggest a formulation that is easier on your gut, or recommend a stool softener.

Over-the-counter simethicone, the active ingredient in many anti-gas products, is generally considered safe during pregnancy and works by breaking large gas bubbles into smaller ones so they pass more easily. That said, always check with your provider before starting anything new during pregnancy.

When to Pay Attention

Routine gas bubbling is harmless, but a few situations warrant a call to your healthcare provider. Severe or persistent abdominal pain that does not resolve with passing gas or changing position is not typical and should be evaluated. The same goes for bubbling or cramping accompanied by vaginal bleeding, especially in the first trimester when ectopic pregnancy is a concern. Sudden, watery gushing or a persistent trickle of fluid from the vagina could indicate ruptured membranes, not intestinal gas, even if you initially mistake the sensation for something moving in your abdomen.

After about 28 weeks, you should become familiar with your baby’s movement patterns. A noticeable decrease in fetal movement is something to report promptly. The concern is not gas but rather the baby’s well-being. If you are used to feeling regular kicks and suddenly only feel occasional gas-like bubbles where strong movements used to be, do not assume it is just the baby resting. Lie on your side, drink something cold, and pay attention for an hour. If movements do not return to their usual pattern, contact your provider.

Phantom Bubbles After Pregnancy

An interesting footnote to the whole experience is that many people continue to feel bubble-like or kick-like sensations in their abdomen after delivery, sometimes for months or even years. These “phantom kicks” have been documented in research but remain poorly understood. One study found that the phenomenon is widely reported among postpartum women and that the mechanism behind it is unknown, though it may involve changes in the brain’s internal map of the body or shifts in how the nervous system processes abdominal sensations after months of pregnancy.⁵

The sensations can be startling, especially if they feel identical to early fetal movement. Some people find them emotionally complicated, triggering either nostalgia or anxiety depending on their circumstances. The phenomenon is benign and not a sign of a new pregnancy or a medical problem, though it does underscore how profoundly pregnancy changes the way your nervous system interprets signals from your abdomen. For many people, those internal bubbles become a kind of sensory echo of the months they spent trying to figure out whether what they felt was gas or a baby.

How Fetal Movements Interact with Amniotic Fluid

If you have ever wondered why certain fetal movements feel liquid or sloshy rather than like a solid kick, the answer involves amniotic fluid. The baby is suspended in fluid throughout pregnancy, and when the baby moves, the fluid shifts around the uterus. Ultrasound research has shown that fetal movement causes a measurable change in the distribution of amniotic fluid, with the fluid index shifting by a couple of centimeters after active movement.⁶ That fluid redistribution is part of why some movements feel like a wave or a bubble rather than a sharp jab. It also explains why the same baby can feel like a gentle swoosh one moment and a firm elbow to the ribs the next: the movement is being transmitted through a liquid medium, and the sensation changes depending on how much fluid is between the baby’s limb and your abdominal wall at that particular moment.

Amniotic fluid volume changes over the course of pregnancy, peaking around 34 to 36 weeks and gradually declining toward term. As the fluid decreases and the baby fills more of the available space, movements tend to feel sharper and more defined. Early in the second trimester, when the baby is small relative to the fluid volume, movements are more likely to feel like soft bubbles. This shifting ratio is another reason why the character of your internal sensations evolves so much from month to month.