According to the results, music is a very special stimulus for pregnant women, to which they react strongly.
"Every acoustic manipulation of music affects blood pressure in pregnant women far more intensely than in non-pregnant women," says Fritz.
Why music has such a strong physiological influence on a pregnant woman is still unknown.
Originally, the scientists suspected the hormone estrogen to play a major part in this process.
This is because it has an influence on the brain's reward system, which is responsible for the pleasant sensations experienced while listening to music.
However, non-pregnant women showed constant physiological responses throughout the contraceptive cycle, which made them subject to fluctuations in estrogen levels.
From 28 weeks, i.e. at the start of the third trimester of pregnancy, the heart rate of the fetus already changes when it hears a familiar song. From 35 weeks, there is even a change in its movement patterns.
The researchers suspect that fetuses are conditioned to music perception while still in the womb by the observed intense physiological music responses of the mothers.
"Either estrogen levels are generally too low in non-pregnant women, or other physiological changes during pregnancy are responsible for this effect," Fritz said.
Another study suggests through a song, the infants are provided with much-needed sensory stimulation that can focus their attention and modulate their arousal.
Simultaneously, mothers experience a much-needed distraction from the negative emotions and thoughts associated with depression, while also feeling empowered as a parent.
"Mothers around the world sing to their infants in remarkably similar ways, and infants prefer these specialized songs," the researchers said.
"The tempo and key certainly don't need to be perfect or professional for mothers and infants to interact through song. In fact, infants may be drawn to the personalized tempo and pitch of their mother, which encourages them to direct their gaze toward and ultimately communicate through this gaze.”