Introduction content of metals in hair is considered a good biomarker to determine the nutritional status and chronic exposure to metals in occupationally and environmentally exposed populations, however, there is not enough information on exposure to essential and non-essential metals in populations vulnerable as are women in pregnancy. Objective: in the present study was to evaluate the concentration of the main metals (essential and non-essential) in hair samples that are transferred from the mother to the newborn during pregnancy. Method: carried out a cross-sectional pilot study from August to October 2015 at the General Hospital “Dr. José María Rodríguez “, located in the municipality of Ecatepec de Morelos, State of Mexico, place with high traffic flow and industries (11,12), in 96 mothers with a geometric mean of 22 years (95% CI 21.99 - 23.45) and their newborns of 39 weeks (IC 95% 39.03 - 39.49) of gestation, inhabitants of said municipality. After the birth, hair samples were obtained from the mother-neonate pairs within a period no longer than 24 hours after delivery. To determine the concentration of metals in these samples, the method of pre-treatment of acid digestion in microwave was implemented and validated for 25 mg of hair sample for newborns and 100 mg for mothers. This allowed to quantify 21 elements (including rare earths) of the reference sample of trace elements in human hair (NCS DC73347A); however, for the samples of this study, the quantification of rare earths was not performed because they were not of interest for the study objectives. Once the pre-treatment was standardized, the hair samples were digested and the metals were quantified by mass spectrometry with source of inductively coupled plasma (ICP-MS). Results: The results showed metal concentrations from 8 ppb to 1190 ppm in the mothers in the following order: Cd <As <Sb <U <Hg <Pb<V <B <Cu <Zn <Ca, while newborns presented concentrations of 3.4 ppb at 1856 ppm in the following order U <As <Cd <Pb <V <Sb <Hg <B<Cu <Zn <Ca. Analysis: The concentrations of some elements were higher in newborns than in mothers, as is the case of Ca (56% higher), Zn (7%), B (66%) and Sb (26). %), the other elements were found in greater proportion in the mother than in the newborn. On the other hand, a positive correlation was observed between the concentrations of Ca, Cu, Zn, As, B, Hg and U in the hair of the mother and that of the newborn. Conclusions: Our data suggest that some metals can be transferred to the fetus during pregnancy, indicating a similar level of exposure between mothers and newborns. Additionally, some metals are able to cross the placenta more easily, which is why they are found in a greater proportion in newborns, possibly due to the characteristics of each metal. Comment, the hair can be a good indicator of the exposure during pregnancy for at least seven elements that correlated positively in the newborn mother binomial; offering the advantage that by knowing the concentration of elements in the hair of the pregnant mother, the exposure of the developing child can be estimated