From the Research
Fetal hiccups in utero are caused by the involuntary contraction of the baby's diaphragm, which is a normal part of fetal development, as evidenced by a study published in 2007 1. This phenomenon is considered a programmed isometric inspiratory muscle exercise of the fetus in preparation for post-natal respiratory function. Some key points to consider about fetal hiccups include:
- They emerge as early as nine weeks post-conception and are the predominant diaphragmatic movement before 26 weeks of gestation 1
- Fetal hiccups serve important developmental purposes, such as strengthening the diaphragm muscle and preparing the respiratory system for breathing after birth
- They also help regulate amniotic fluid levels as the baby practices breathing movements
- Hiccups may stimulate nerve pathways that control breathing, contributing to the maturation of the baby's central nervous system
- Most fetal hiccups last only a few minutes and occur several times a day, which is completely normal
- Mothers typically feel these hiccups as rhythmic, consistent movements that differ from regular kicks or movements It's worth noting that while fetal hiccups are generally a normal and harmless phenomenon, excessive or prolonged fetal movements can be a sign of fetal compromise and may require further examination, as suggested by a study published in 2018 2. However, this is not directly related to the cause of fetal hiccups, but rather a potential concern that may arise in certain cases. In terms of the underlying mechanisms, a study published in 2015 proposed that hiccups may serve a purpose in regulating amniotic fluid influx to the primitive gut 3. Additionally, research on fetal breathing and development of control of breathing has shown that breathing movements are an important part of fetal development, and that the control of breathing in utero differs from that after birth 4. However, the most recent and highest quality study on the topic of fetal hiccups is the 2007 study published in Physiological measurement 1, which provides the most relevant evidence for understanding the cause of fetal hiccups.