[Prevalence of low weight at birth and related factors].

Objective: To measure the prevalence of low birth weight and its possible association with risk characteristics at an international level.

Patients And Methods: An analytical and transversal study was performed during 2003. Newborns attended at the gynecological unit of the Hospital General de Zona Num. 35 in Cosamaloapan, Veracruz, were selected. The neonates included had a neonatal screening for hypothyroidism, as well as a newborn registration format. Pediatricians and pre-graduate interns evaluated: weight at birth, sex, maternal age, weeks of gestation, number of pregnancies, place of residence and the mother's occupation. Low birth weight was defined as the newborns that weighed less than 2,500 g.

Results: A total of 751 newborns were evaluated. In accordance to the characteristics of the mother, the mean age was of 25.9 +/- 5.9 years, 104 (13.8%) were adolescents, and 256 (35.3%) were first time mothers. The low birth weight existed in 43 (5.7%) of the newborns, and the birth weight of 708 (94.3%) was > or = 2,500 g. The maternal age, the number of pregnancies, the place of residence and the mother's occupation were not statistically related with the low birth weight.

Conclusions: The prevalence of low birth weight is lower than the data reported internationally, and it could be explained by the period in which the study was performed. None of the characteristics assessed as risk factors demonstrated to be associated.