Why do babies hiccup in utero?

There is not a great deal written in the medical resources about foetal hiccuping even though it is such a common feature during a pregnancy, and usually experienced at least once by most mums as distinct, episodic movements of their foetus. It is certainly a foetal reflex similar to our own. In this reflex (which is an involuntary movement in an area) there is a sudden spasmodic contraction of the diaphragm and closure of the sound-producing folds at the upper end of the windpipe. Usually, of course, there is a sudden drawing in of breath, and we make an accompanying noise. Thank goodness that doesn’t happen in utero – could be quite disturbing!

In the case of the foetus there has been shown to be a drawing in of some of the amniotic fluid in which it floats. It seems that it is only the more mature foetuses that show this (because of the development of the central nervous system at that time). Some think that the ‘hiccup reflex’ is a response to foetal drinking or foetal breathing which causes this flow of amniotic fluid in and out of the lungs, thus stimulating the diaphragm to contract, just as it does in the normal hiccup situation.

Thanks for asking, it’s an interesting question.