RESUMEN
Through participation of ten hospital institutions in the city of San Luis Potosí, which systematically take care of newborns, the present collaborative study was performed; this includes all births during the period from january 1st. to december 31st., 1988. The births taken place at home and other sites such as the "Hospital Materno Infantil" during the last six months, were excluded from the study; they accounted approximately 10%. We registered 17,092 births including 204 mortinates. Based on the upper data, the following chart is given, stating weight as well as gestation rates. Precocious fetal mortality (500 to 999 g)--391.30 by thousand; Precocious fetal mortality (20 to 27 weeks)--140.40 by thousand; Late fetal mortality (1,000 g or more)--9.25 by thousand; Late fetal mortality (28 weeks or more)--9.89 by thousand; Hebdomadal mortality (500 to 999 g)--571.40 by thousand; Hebdomadal mortality (20 to 27 weeks)--159.40 by thousand; Hebdomadal mortality (1,000 g or more)--11.96 by thousand; Hebdomadal mortality (28 weeks or more)--12.62 by thousand; Perinatal mortality (1,000 g or more)--21.10 by thousand; Perinatal mortality (28 weeks or more)--22.38 by thousand. The IMSS sent for registration 8,710 births which accounted 51% of the total. Their data revealed the highest values in all rates. In precocious fetal mortality (products between 20 and 27 weeks), the rate value was 543.9 against 140.4 globally counted. Hebdomadal mortality for this 20 to 27 weeks group showed 730.8 against 159.4 globally reported. In 199 out the 204 mortinates, cause of death was registered; 49.7% of these causes was reported as placental circulation insufficiency and 17.1% as major congenital abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)