Talking to the baby or rubbing an expectant mother’s stomach is common throughout pregnancy. However, researchers have found that fetuses respond more to their mother’s touch than to her voice, according to a study published earlier this June in PLoS ONE.

Newborn children respond well to female voices after birth, leading researchers to believe that fetuses may be able to react to sound and touch. Fetuses in previous recordings have responded to these stimuli as early as 16 weeks old. Previous attempts to measure fetal ability to react to stimuli have resulted in inconclusive results, possibly due to different methodologies.

For this study at the University of Dundee, 23 mothers were selected. The expecting mothers in the study did not smoke, drink, or use drugs during their pregnancies, and did not report any major stressors during their pregnancies.

The fetuses were between the 21st and 33rd week of gestation. All expecting mothers participated in three conditions — voice, touch, and control. For the voice condition, the mothers read a story to their fetus, either Three Little Pigs or Jack and the Beanstalk. For touch, mothers rubbed and stroked their stomachs. The researchers made note that the ‘touch’ stimulus was not direct contact, but instead “indirect stimulation of the fetus via stroking the abdomen applying slight pressure.” Finally, for control, the mothers laid silently with their hands by their sides.

Not only did fetuses respond more to touch, but older fetuses showed more movement than younger fetuses. The older fetuses showed more self-touch, like hands touching their body, than the younger fetuses. Older fetuses have decreased movement due to their growing size, but were more active than the younger fetuses in the study. Younger fetuses, however, responded to touch earlier in gestation than originally thought, a difference of five weeks.

“Overall results suggest that maternal touch of the abdomen was a powerful stimulus, producing a range of fetal behavioural responses. Fetuses displayed more arm, head, and mouth movements when the mother touched her abdomen as compared to maternal voice in situ,” the researchers wrote in their study.

“In summary, the results from this study suggest that fetuses selectively respond to external stimulation earlier than previously reported, fetuses actively regulate their behaviours as a response to the external stimulation, and that fetal maturation affects the emergence of such differential responses to the environment.”

These movements responses may indicate that fetuses are trying to communicate with their mothers, fathers, and family members. Further research is necessary to truly determine the intent of fetal responses to touch and sound.