The multiple pregnancy now a days is acquiring epidemic dimensions, mainly due to the induction of the ovulation and the more frequent use of techniques of assisted reproduction. It is known through diverse studies that the fetuses coming from multiple pregnancies possess a risk of fetal death between 5 and 10 times superior to that of simple type and they are also prone to present under weight and a series of morbid episodes comparatively with the unique fetuses. Objective: To determine the risk of mortality and to estimate the level of fetal survival according to pregnancy type and its associate factors. Methodology: The rates of fetal mortality were calculated according to factors like maternal age, number of previous pregnancies, abortions, sex of the fetus and weight at the moment of the expulsion, according to the pregnancy type. Cohorts of pregnancies were also reconstructed with what was possible to apply life table technics in order to estimate the curves of survival of the fetus in uterus. Results: It was confirmed the character of risk of the multiple pregnancy with regard to the simple one, nevertheless a group of paradoxes came out to light like that of the advanced maternal age for multiple pregnancies, which evidences that to more maternal age the risk of experiencing fetal death decreces in the multiple pregnancies. Something similar happened with the number of previous pregnancies had by the pregnants. Another paradoxical fact constituted the weight, for conduit of which was showed that in the inferior categories of weight, the fetus coming from a multiple pregnancy possesses a similar and even smaller risk than the simple one and consequently a superior survival in uterus.
Keywords: Pregnancy type, multiple-simple over risk, fetal survival.