We did a case-control study to verify if the birthweight, forceps delivery or perinatal asphyxia have any significant effect on the prognosis of obstetrical brachial plexopathy. Group A was composed of 25 infants who completely recovered at the age of 6 months. Group B was composed of 21 infants who were still not able to remove a blindfold from the face with the affected limb in the sitting position at the age of 12 months. There was no statistical difference of the median birthweight or median first minute Apgar score between the groups. There was also no relation between birthweight higher than 4000 g, first minute Apgar score lower than 6 or forceps delivery with a poor prognosis.