Some healthcare superstitions may be rooted in truth. But most of these hand-me-down stories are myths that persist, despite being repeatedly proven invalid, causing undue stress for expecting parents.
One such myth is that a baby with hiccups in the womb may indicate potential danger in utero.
Concerns over fetal hiccups may be based on old animal studies. According to one researcher’s 2012 article in BMC Pregnancy and Childbirth, it’s suggested that hiccups in utero might be caused by compression of the umbilical cord. His possible explanation is that hiccupping might make a fetus move away from the cord, which would relieve the compression and return blood flow to normal.
However, I couldn’t find the study, which involved fetal sheep, that he quoted.
Much like the “vaccines cause autism” lie, which has been perpetuated since a now-discredited study in the late 1990s, people grabbed onto the idea that fetal hiccups could cause problems like preterm birth or stillbirth – none of which has ever been scientifically studied in human fetuses.
I can understand why patients might be worried about hiccups. It looks strange on ultrasound to see your baby jerking around in the womb. It’s only natural to Google the phenomenon, only to find article after article suggesting that your pregnancy may be at risk.
Fetal hiccups are normal. Having hiccups does not mean something is wrong with your baby, and you don’t need to try to get rid of the condition. Let’s look at the data to prove it and discuss what’s really going on in your belly with every hic, hic, hiccup.
What happens during fetal hiccups?
In the fetus, the diaphragm acts similarly to how it will when the baby is born. The diaphragm controls breathing, which is a rhythmic, intermittent movement. The fetus isn’t breathing air, but amniotic fluid – the liquid that surrounds the fetus during pregnancy.
With each inhalation, the diaphragm – a muscle below the lungs – moves down. This causes a downward and outward displacement of the abdomen. Instead of the chest rising and falling with breaths like an adult’s would, fetuses and babies tend to involve their bellies more. This gentle movement is undetectable by the pregnant patient.
Hiccups follow that same, rhythmic motion as breathing, but more forcefully. The entire fetal body moves in a jerking motion with each hiccup, which many pregnant patients can feel. Just like in babies and adults, fetal hiccups occur for a short, consistent period of time, then go away on their own.
A closer look at fetal hiccups
Ultrasounds show normal fetal breathing and fetal hiccups, which are not a danger to the fetus or the pregnancy.
What does the science say?
There are several problems with the study that suggests hiccups are associated with potentially dangerous umbilical cord compression. The researcher speculates that hiccups are a hyper-reactive response to reduce blood flow from a knotted or compressed umbilical cord.
Umbilical cord problems are always high on our radar. Patients worry about this, and we are always on top of the latest research and data on the topic. That said, I’ve never encountered any data that suggest fetal hiccups are associated with poor pregnancy outcomes – either in published research or anecdotally in the clinics at UT Southwestern.
When we see cord compression, it’s usually in the presence of other events, such as:
- When the patient’s water breaks early. Less fluid around the umbilical cord means there’s a chance the baby could roll onto it, reducing blood flow. We typically put patients in the hospital after their water breaks to monitor the fetal heart rate as an indicator of potential issues.
- Labor and delivery. This happens fairly often. When the uterus contracts, it can compress the umbilical cord. When the uterus relaxes, the compression usually goes away. This appears as variable decelerations on the fetal heart monitor and is no cause for alarm.
If we are to believe that hiccups are a result of cord compression, it would stand to reason that fetuses would develop hiccups in these instances. But I’ve never seen this reported from any institution, and I’ve never seen it happen in my many years as a clinician.
Fetal heart rate is a known marker of well-being, as is being able to feel the baby move. In a 2017 study published in BMC Pregnancy and Childbirth, 150 women who had stillbirths in the third trimester responded to a poll regarding their memories around fetal movement, including fetal hiccups. The researchers compared these women’s responses with those of 500 women who had live births or were still pregnant in the same timeframe.
Approximately 80 percent of women in both groups remembered experiencing fetal hiccups – there was no significant difference between the responses of either group of women, suggesting that fetal hiccups are not associated with adverse pregnancy outcomes. The same was true when the data were adjusted by maternal age, body mass index, smoking, or whether the patient felt daily or prolonged hiccups.
Slightly more women who had a stillbirth recalled daily fetal hiccups than those in the control group – 58% vs. 44% – but when this many report daily hiccups, it can’t be used as a marker for a fetal problem.
How can I tell hiccups from fetal kicks?
Hiccups typically have a regular rhythm and occur in the same part of the belly over and over for a few minutes. Hiccups will feel like a jerking or pulsing jump, which may move your belly a bit.
Kicks typically are not rhythmic and will occur all around the belly. “Kicks” may be the baby’s head, arms, bottom, or feet bumping against your insides, and they sometimes feel and look like a rolling movement rather than a quick jab.
What if I’m worried about the baby’s movements?
Anytime you are concerned, reach out to your Ob/Gyn or certified nurse-midwife. We would rather you call us than sit and worry about something that may not be cause for alarm. It’s important to call your prenatal care provider if you notice negative changes in fetal activity, such as drastically reduced movement during typically high-activity times.
However, we encourage you to take episodes of fetal hiccups for what they are – normal, non-harmful, and pretty cute! – bursts of fetal movement.