Your baby gets hiccups in the womb because their diaphragm contracts in quick, rhythmic spasms, just like it does when you hiccup after birth. This is completely normal and, for most of pregnancy, actually serves a developmental purpose. You can typically start feeling these little jolts between 21 and 24 weeks, though they’ve been happening since well before you could notice them.
What Triggers Fetal Hiccups
Hiccups are a reflex controlled by the brainstem, specifically a region called the medulla. Even in a developing fetus, this reflex arc is already wired and active. When the diaphragm (the thin muscle beneath the lungs that powers breathing) contracts involuntarily, it creates a quick intake of amniotic fluid rather than air, producing the rhythmic twitching you feel from the outside.
One hypothesis is that changes in amniotic fluid pressure may trigger hiccup episodes. As your baby swallows amniotic fluid and moves around, shifts in pressure could stimulate the reflex. This fits with the broader pattern: fetal hiccups appear to be closely tied to how your baby interacts with the fluid environment around them.
Why Hiccups May Help Your Baby Develop
Hiccups aren’t just a quirky side effect of having a diaphragm. Researchers believe they serve at least two purposes during pregnancy.
The first involves fluid regulation. A leading hypothesis proposes that hiccups help move amniotic fluid into your baby’s primitive gut during the first half of pregnancy, when hiccups are most frequent. This allows fluid to be absorbed into the fetal bloodstream and eventually cycled back through the maternal circulation. In other words, hiccups may be part of how your baby’s body learns to manage the fluid it’s floating in.
The second involves the diaphragm itself. Studies tracking fetal movements across the second and third trimesters found that hiccups were the dominant type of diaphragmatic movement before 26 weeks. That’s significant because during this stage, the lungs aren’t yet mature enough for breathing practice. Hiccups may essentially give the diaphragm a workout before the more complex breathing movements take over later in pregnancy.
When Hiccups Are Most Common
Fetal hiccups follow a clear pattern across pregnancy. They’re most frequent in the second trimester, peaking before 26 weeks. After that, there’s a pronounced drop, not because each episode gets shorter, but because the episodes happen less often. By the third trimester, your baby is spending more time practicing actual breathing movements, and hiccups become less dominant.
That said, you’ll probably notice hiccups more in the third trimester simply because your baby is bigger and stronger. Earlier episodes may have been too subtle to feel. Once you do notice them, episodes can last anywhere from a minute to an hour, and they may happen several times a day. This is all within the range of normal.
How to Tell Hiccups From Kicks
Fetal hiccups feel distinctly different from kicks, rolls, or stretches. The key feature is rhythm. Hiccups produce a repeating, evenly spaced jerking sensation, almost like a tiny pulse in the same spot. Kicks and punches tend to be irregular, stronger, and come from different angles as your baby shifts position.
You might even see hiccups from the outside as small, rhythmic jumps on your belly. They tend to be felt lower in the abdomen, near where your baby’s chest is positioned. If you’re unsure, place your hand on the spot. A steady, metronome-like tapping is almost certainly hiccups.
When Frequent Hiccups Deserve Attention
For the vast majority of pregnancies, fetal hiccups are harmless and expected. However, research in animal models has found that intermittent compression of the umbilical cord can trigger hiccups. Because of this, a specific pattern has been flagged as worth mentioning to your provider: hiccups that occur daily after 28 weeks and happen more than four times per day.
This doesn’t mean frequent hiccups are dangerous. Most of the time, a baby who hiccups a lot is simply a baby who hiccups a lot. But because fetal jerking movements and hiccups can occasionally be related to blood flow disturbances, particularly cord compression, some clinicians recommend an ultrasound to check on things if the pattern is unusually persistent. The goal isn’t to cause alarm but to rule out a rare complication.
Outside of that specific pattern, occasional daily hiccups, even long episodes, are a sign that your baby’s nervous system and diaphragm are developing exactly as they should.