According to Med-Health.net, fetal hiccups occur for several reasons, including a contracting diaphragm, cord compression and reflex development. Hiccupping in the womb is normal and should not be a cause for concern.
As Med-Health.net explains, when the central nervous system is developing, it sends signals to the brain to contract the diaphragm so that the baby may begin breathing. The sudden contraction creates a sensation that feels like a hiccup. In rare cases, hiccups may indicate that the umbilical cord is wrapped around the baby's neck. If the doctor considers this a possibility, he will perform an ultrasound. Babies begin to practice the rooting reflex inside the womb; the suckling creates a sensation that emulates hiccups.