At this time no one can deny anymore the ability of the fetus to respond to external physical stimuli. We have previously demonstrated that :1) Fetuses respond to vocal stimulation 2) The reaction is stronger if the stimulus comes from their mother 3) And even more important, if the speech is addressed to them 4) And / or has an emotional content 5) Neonates and fetuses respond in the same way whether mothers address them vocally or "silently". Aim of the study: We tested the individual response of twins in utero to a silent communication specifically addressed to each one. Methods: Eighty seven (87) women participated in the study. They were tested between 28 and 39 weeks of amenorrhea. A total of 349 tests comprise the study. In the experimental group, mothers were instructed to read a text in silence and to communicate silently (without speaking aloud) with one twin and subsequently with the other twin. In the control group, mothers were reading a text in silence during 30 minutes.Measures During the test, heart rate of the mother and that of each fetus were recorded as well as the maternal uterin tonus and number of contractions. The number of twins whose heart rate was modified during silent communication were counted in the control and the experimental group. Results: In 33% of the tests, there is a change in the fetal heart rate of the targeted twin towards which the mother's attention is directed (silent communication). In some cases, the answer was not the one expected (the heart rate of both twins changed 16%, a change in the heart rate of the non-targeted twin occurred 9%, the heart rates of both twins did not change 41%). The experimental data differ significantly from those obtained in the control data. Conclusion: this study demonstrates that silent communication with one twin changes the fetus’s heart rate significantly when compared to the non-targeted twin as well as when compared with controls. These new findings raise fundamental questions about the nature of a stimulus and about the development of these finely-tuned responses in the fetus. Further longitudinal studies of the mother-twin pairs should characterize mother-fetus interactions and the different modalities of the silent communication in early life.