The Valentine's Day , a date that lovers around the world commemorate the mutual expression of love is also the time chosen by women to give birth to their children , according to a study that analyzes the influence of beliefs in human body functions. Evidenced by a recent investigation by the Yale University performed on millions of birth certificates in recent years in America. On 14 February the natural births rose by 3.6 percent and cesarean at 12.1 percent. Instead, the day that we celebrate Halloween (witches night, Oct. 31) natural births fell by 5.3 percent and caesarean sections showed a decrease of 16.9 percent. "The partnership between the two dates has never been investigated so far. Our research suggests that beliefs derived from our culture can have a major impact on body functions, to the point of influencing not only scheduled deliveries but also the natural birth, "said Becca Levy, director of the study published in the journal Social Science & Medicine and professor of epidemiology and psychology at Yale Medical School. The research confirms "that women are not taxable at the time of the happy event but assume a decisive role which can facilitate the birth or postpone it." "The symbolism of the two dates is the opposite. Halloween Day is associated with witches and death and is considered an unfavorable time to be born. Instead, Valentine flowers and symbol of love, is considered an auspicious day, "said Levy. On this subject, also said Gilberto Corbellini, philosopher and historian of medicine at the University of Rome Sapienza. "Today we have a technology that allows a certain margin of freedom to plan and control the date of births with deliveries scheduled but the medicine is, as always, strictly linked to the environment and the cultural and social context. To this point, which may influence the response of patients sick, "he said. According to the philosopher, cultural representations and stereotypes "affect the birth, on the health and even death." "The pagan religious dates can also develop the famous" placebo effect "facilitating the relaxation of pregnant women or, conversely, increasing the level of stress," he said. Beyond indicating the research to Corbellini "it is not surprising that culture influences the preferences and that women are more affected contexts better and to prefer an atmosphere of celebration to bring the world to their children."