[Maternal age as a risk factor for congenital malformations]. / Edad materna como factor de riesgo para malformaciones congénitas.

We studied 131,899 consecutive births at the Maternity of the University of Chile Clinical Hospital, finding 4887 newborns with congenital malformations (representing a rate of 37.05 per 1000 alive newborns). Between January 1982 and December 1992 there were 41,344 births and 295 stillbirths (0.7%). Among the latter, 41 were malformed (13.9%). A graphic comparing the mean annual rates of malformations and maternal ages, shows a sustained increase in malformations form 1972 to 1988, that decreases thereafter and stabilizes since 1982. There is a marked parallelism between the curves of malformation rates and maternal age (t21 = 1.057, p < 0.1). It is concluded that the risk of congenital malformations increases along with maternal ages.

[MN blood group and congenital malformations]. / Grupo sanguíneo MN y malformaciones congénitas.

This work analyzes the mother-son segregation of MN blood group in malformed and normal newborns. MN blood group was measured in 90 malformed, 70 paired normal newborns and their respective mothers, at the Maternity of the University of Chile Clinical Hospital. The expected values for the different mother-child pairs were calculated according to the ITO matrix method, using maximally probable appraisers. Among malformed newborns, there was an excess of heterozygous sons when the mother was homozygous for the MN system. Among malformed males, there was an excess of MM-MN and MN-MM mother-son pairs. Among control newborns, no distortions were found. These results suggest that there is a strong association between MN heterozygosis, sex and congenital malformations.

[Epidemiologic study of factors associated with hypospadias]. / Estudio epidemiol ogico de factores asociados a hipospadias.

From August 60 to December 90, 103 male newborns with hypospadias were diagnosed among 124 588 consecutive newborns examined (8.3 per 10,000). Mortality among them was 1.94%. The annual incidence rate increased significantly over the study period (p < 0.001. Hypospadias was an isolated finding in 92% of cases, and its was associated to other non genital malformation in 8.7%. Location of hypospadias was distal in 73% and proximal in 15.5%. There was no seasonal variation in the incidence rate. Weight of affected individuals did not differ from that of controls. Older age of parents among affected individuals was not statistically significant.

[Incidence of malformations of the central nervous system: 1978-1988]. / Incidencia de las malformaciones del sistema nervioso central: período 1978-1988.

During the period Jan 1978 to Dec 1988, 41,867 deliveries took place at the University of Chile Hospital. Among them, 148 babies were found to have malformations of the central nervous system, an incidence of 3.6 per 1000 live births. A longitudinal study from 1969 to 1988 suggests a yearly increment of 0.1% in the incidence rate of these malformations. The comparison of some quantitative variables, such as gestational age, birthweight, number of previous abortions and some risk factors like maternal illness, bleeding, radiation exposure, drug ingestion during the first trimester of pregnancy and instructional level of both parents show significant differences between the malformed and the control newborns. No significant differences were found for maternal age, sex nor seasonal variation.

[Incidence of congenital malformations among stillborns]. / Incidencia de malformaciones congénitas en mortinatos.

During the period 1982-1986 there were 168 stillbirths out of 20,669 consecutive deliveries (0.81%) at the University of Chile's Clinical Hospital. The incidence of congenital malformation was 6.26% in the liveborn population and 14.29% in the stillborns. There was a significant statistical difference between these two groups of malformed newborns regarding maternal age, parity and birthweight. The incidence rate of ten selected major congenital anomalies in the two groups showed highly significant differences, being higher among stillborns.

[Incidence of congenital malformations in Chile from 1969 to 1986. Results of a Latin-American collaborative study]. / Frecuencia de malformaciones congénitas en Chile en el período 1969-1986. Resultados de un estudio colaborativo latinoamericano.

At present, congenital malformations contribute more to infant mortality, given the significant decrease in overall infant mortality rate observed in Chile. A significant and steady increase in the prevalence of congenital malformations was demonstrated at the Clinical Hospital, University of Chile, from 1969 to 1986. Better epidemiologic surveillance is needed to accurately estimate the magnitude of this problem and give orientation for preventive measures.