Hiccups are a common occurrence for babies in the womb. Some pregnant women can feel their baby’s hiccups as early as the second trimester. While hiccups may seem like fetal movement to the mother, they are different from kicks and punches and are technically not considered fetal movement by medical professionals.
What are hiccups?
Hiccups are involuntary contractions of the diaphragm muscle that are triggered by irritation of the nerves that control the diaphragm. The irritation causes the diaphragm to contract rapidly, which results in the “hic” sound that gives hiccups their name.
In babies in the womb, hiccups serve no real purpose. They are thought to be caused by immature central nervous system control of the diaphragm muscle. As the baby’s brain and nervous system continue to develop and gain control over body functions, hiccups usually taper off and disappear by the time the baby is born.
Why do babies get hiccups in the womb?
There are a few theories as to why babies get hiccups before they are born:
- Immature central nervous system – As mentioned, the baby’s brain and nerves are still developing their control over muscles like the diaphragm. The immaturity can result in occasional uncontrolled contractions.
- Breathing practice – Fetal hiccups may help exercise the lungs and diaphragm to get ready for breathing after birth.
- Stimulation – Things that stimulate the baby like the umbilical cord wrapping around their body, loud noises outside the womb, or certain foods the mother eats may irritate the nerves and trigger hiccups.
While the exact causes are unknown, hiccups are very common in fetuses and considered a normal part of development.
How common are fetal hiccups?
Studies show that over 80% of fetuses will get hiccups at some point during the pregnancy. Hiccups tend to be most common during the third trimester between weeks 31-40.
Some studies have found the following about fetal hiccup frequency:
Gestational Age | Percentage of fetuses with hiccups |
---|---|
28-32 weeks | 54% |
33-36 weeks | 74% |
37-40 weeks | 88% |
As you can see, the occurrence of hiccups increases significantly as the due date approaches.
Do hiccups feel like kicks for the mother?
While hiccups are common in the womb, most pregnant women cannot actually feel them. This is because hiccups cause small, subtle repetitive motions rather than the strong kicks and jabs of arms and legs.
However, some women in the late third trimester report feeling a pulsing, rhythmic tapping when their baby gets the hiccups. These sensations are typically intermittent and last only 30 seconds to a few minutes at a time when the baby is hiccuping.
So while some moms can feel hiccups, the sensations are distinct from the larger movements of fetal kicks and stretches. If a pregnant woman feels rhythmic pulsing in her belly, it may be from hiccups rather than kicks.
Why don’t hiccups qualify as fetal movement?
There are a few key reasons why hiccups don’t count as fetal movement from a medical perspective:
- Type of muscle contraction – Hiccups involve involuntary contractions of the diaphragm muscle only. Fetal movement involves purposeful contractions of large muscle groups like arms and legs.
- Strength of motion – The muscle spasms of hiccups create subtle motions rather than strong kicks or punches.
- No central nervous system involvement – Hiccups originate from irritations of the phrenic nerves rather than conscious brain activity like fetal movements do.
- Repetitive nature – Hiccups occur in rhythmic repeats rather than the variable patterns of kicks and movement.
Due to these distinct differences, doctors define fetal movement as voluntary positioning and muscle contractions that require CNS input. The involuntary reflex of hiccups does not qualify.
How are fetal hiccups monitored?
Since hiccups don’t count as fetal movement, they are not specifically monitored by obstetricians. However, fetal hiccups may be observed during certain ultrasound exams:
- Third trimester growth scan – 30-32 weeks. A full anatomical survey that may detect hiccups.
- Biophysical profile – 32+ weeks. 30 minute in-depth exam that includes observation for hiccups.
Doctors do not rely on the presence or absence of hiccups during these exams though. Only purposeful movements, breathing, muscle tone, and amniotic fluid levels are scored.
When should decreased fetal movement be a concern?
Since hiccups are involuntary actions, a change or halt in fetal hiccups is NOT considered decreased fetal movement. Only changes in purposeful kicks and movement should be reported to a doctor.
Signs to report include:
- Less than 10 perceived movements in 2 hours (after 28 weeks)
- Complete absence of perceived movement for 12+ hours
- Significantly slower or less vigorous movement overall
Decreased fetal movement can be a sign of potential problems. But changes in hiccups alone are not cause for concern.
Conclusion
In summary, fetal hiccups are common and normal, but they are not considered true fetal “movement” for medical purposes. While some moms can feel hiccups in late pregnancy, they are distinct from purposeful kicks and stretches. Hiccups originate from nerve irritation rather than CNS input. They also involve only the diaphragm, occur rhythmically, and are subtle. Obstetricians monitor only purposeful fetal activity and movement patterns, not hiccups, to ensure fetal well-being.