Prevalencia al nacimiento de malformaciones congénitas y de menor peso de nacimiento en hijos de madres adolescentes / Prevalence of congenital malformations and low weight at birth among teenage mothers

BACKGROUND: In Chile, 14 to 16 per cent of births occur in teenage mothers. These mothers apparently have a higher frequency of premature labor, low birth weight and congenital malformations. AIM: To assess the frequency of prematurity, congenital malformations and weight at birth among the offspring of adolescent mothers. PATIENTS AND METHODS: The births occurred in a hospital between 1982 and 2001, were analyzed using the Latin American Collaborative Study for Congenital Malformations (ECLAMC) data base. Mothers were classified as teenagers when their age ranged between 10 and 19 years old and older when their age was over 20 years old. All women were subdivided as cases and controls. RESULTS: The sample was formed by 894 teenage and 806 older mothers. Seven percent of both teenage and older mothers had offspring with one or more malformations. The incidence of low birth weight newborns and of prematurity was also similar in both groups of mothers. CONCLUSIONS: In this sample, offspring of teenage mothers do not have a higher frequency of malformations, low birth weight or prematurity.

Quiste ovárico fetal: diagnóstico ecográfico prenatal. Evolución y tratamiento postnatal. Casos clínicos / Fetal ovarian cyst: prenatal echographic diagnosis. Evolution and postnatal treatment. Clinical cases

Ovarian cysts are found in 32 per cent of necropsies performed to neonates. They can also be diagnosed during gestation by ultrasonography. The clinical evolution of these cysts is variable, but in most cases the prognosis is favorable. Some complications such as ovarian torsion, bleeding, rupture and peritonitis have been described. We report two newborn girls with ovarian cysts, diagnosed during gestation. One required an emergency operation due to vomiting and abdominal distension, interpreted as a possible torsion of the cyst. The second girl was operated at the fourth day of life, finding a left ovarian cyst with torsion of the pedicle. Both girls had a favorable postoperative evolution.

Prevalencia al nacimiento de aberraciones cromosómicas en el Hospital Clínico de la Universidad de Chile. Período 1990-2001 / Prevalence of chromosomal aberrations at birth in the Clinical Hospital of Universidad de Chile, 1990-2001

BACKGROUND: A cytogenetical study should be performed to every newborn with malformations. If a chromosomal aberration is found, parents must be studied to give an adequate genetic advise. AIM: To study the frequency of chromosomal aberrations in newborns with malformations. PATIENTS AND METHODS: In the Clinical Hospital of the University of Chile all malformations in newborns are registered, as part of the Collaborative Latin American Study of Congenital Malformations (ECLAMC). The frequency of chromosomal aberrations, determined by cytogenetical studies, was determined in newborns with malformations. RESULTS: In the study period, there were 32,214 births. Of these, 2,268 live newborns and 43 stillbirths had malformations. Ninety nine children with malformations had chromosomal aberrations (4.3 per cent). Trisomy 21 was the most common aberration with a rate of 23/10,000 births, followed by trisomy 18 with a rate of 4/10,000 and trisomy 18 with a rate of 1.2/10,000. Ninety four percent of these children were born alive and 16.1 per cent died before discharge from the hospital. The masculinity indexes for Down syndrome and for trisomy 18 were 0.38 and 0.61 respectively. CONCLUSIONS: A higher frequency of female gender for trisomy 21 and male gender for trisomy 18 has not been reported previously.

[Congenital malformations in Chile. An emerging problem (period 1995-1999)]. / Malformaciones congénitas en Chile. Un problema emergente (período 1995-1999).

BACKGROUND: The Latin American collaborative study of congenital malformations (ECLAMC) is a surveillance program designed to monitor the frequency of congenital malformations and detect abrupt changes in their frequency, look for the cause of such change and implement primary prevention measures. AIM: To construct a secular trend curve with the frequency of congenital malformations in Chile. MATERIAL AND METHODS: Using the ECLAMC protocol, every malformed newborn or stillbirth, weighting more than 500 g at birth is registered using a standard protocol, and the next non malformed child of the same sex born in the same hospital is assigned as control. Using the gathered data, secular trend curves of congenital malformations were constructed. RESULTS: Between 1982 and 1999, there is a secular tendency in the rate of congenital malformations and maternal age, with a correlation coefficient of 0.8 and slope of 13.5 (p < 0.05). The rates of congenital malformations at the moment of birth are higher at the University of Chile Clinical Hospital than in the rest of Chilean hospitals and other Latin American Hospitals. Anencephaly is a defect with a high frequency in Concepción and spina bifida has a high frequency in Rancagua, Viña del Mar, Concepción and Valdivia. There is an impressive increase in malformations dependent on prenatal diagnosis such as kidney agenesis, polycystic kidney and diaphragmatic hernia. CONCLUSIONS: Congenital malformations are having an increasing importance as causes of morbidity or mortality in the newborn.

Identification of novel mutations in SHH and ZIC2 in a South American (ECLAMC) population with holoprosencephaly.

Holoprosencephaly (HPE) is genetically heterogeneous with four genes, SIX3, SHH, TGIF, and ZIC2 that have been identified to date and that are altered in 12% of patients. To analyze this prevalence in a South American population-based sample (57 HPE cases in 244,511 live and still births or 1 in 4300), we performed a mutational study of these genes in 30 unrelated children (26 newborns and 4 non-newborns) with HPE being ascertained by ECLAMC (Latin American Collaborative Study of Congenital Malformations). We identified three novel mutations: two were missense mutations of the SHH gene (Cys183-->Phe; His140-->Pro); the third mutation was a 2-bp deletion in the zinc-finger region of the ZIC2 gene. These molecular results explained 8% (2/26 newborn samples) of the HPE cases in this South American population-based sample, a proportion similar to our previously published data from a collection of cases.

[Ambiguous sex: prevalence at birth in the maternity ward of the clinical hospital of the university of Chile]. / Sexo ambiguo: prevalencia al nacimiento en la maternidad del Hospital Clínico de la Universidad de Chile.

BACKGROUND: Ambiguous sex has a great phenotypic variability and is a serious medical and social problem. AIM: To study the prevalence of ambiguous sex among newborns. MATERIAL AND METHODS: As part of the ECLAMC (Cooperative Latin American Study of Congenital Malformations) all newborns with malformations are registered and the next normal newborn is considered as a control. RESULTS: 50.253 births occurred (between 1982 and 1999) in the University of Chile Maternity Hospital. The rate of congenital malformations was 6.78% and the prevalence of ambiguous sex was 4.7 per 10.000 births. Affected children had a lower birth weight, lower gestational age and a lower maternal age than controls. The most frequent associated malformations were of the urinary (64%) and cardiovascular systems (60.7%). Thirty two percent of affected children had specific syndromes. CONCLUSIONS: The prevalence of ambiguous sex in this study was 4.7 per 10.000 births, which is higher than that reported in the ECLAMC (1.9 per 10,000).

[ECLAMC: 30-year study of epidemiological surveillance of neural tube defects in Chile and Latin America]. / ECLAMC: estudio de 30 años de vigilancia epidemiológica de defectos de tubo neural en Chile y en Latinoamérica.

BACKGROUND: There is an urgent need to assess the impact, on the incidence of neural tube defects, of the recently implanted flour fortification with folic acid in Chile. The Collaborative Study of Congenital Malformations in Latin America (ECLAMC) has carried out an uninterrupted register of congenital malformations in the last thirty years. AIM: To assess the epidemiology of neural tube defects in Chile and determine the most adequate base period to evaluate the effects of Folic acid fortification. MATERIAL AND METHODS: Analysis of ECLAMC database that has registered all births over 500 g from 1967. RESULTS: From 1967 to 1999, there were 434.624 births in 18 hospitals in Chile and 3.586.569 births in 155 hospitals in the rest of Latin America. The rate of neural tube defects in Chile was 17.03 per 10.000, significantly higher than the rest of ECLAMC (14.88 per 10.000). The prevalence of neural tube defects has a statistically significant secular tendency to increase in the study period and is higher among stillbirths, newborns with a birth weight of less than 1500 g, women and offspring of mothers aged less than 19 years old. CONCLUSIONS: The period 1982-1999 is considered the best period for reference comparisons of the effects folic acid supplementation.

[Incidence of the cleft lip and palate in the University of Chile Maternity Hospital and in maternity Chilean participating in the Latin American Collaborative Study of Congenital Malformations (ECLAMC)]. / Incidencia de labio leporino y paladar hendido en la Maternidad del Hospital Clínico de la Universidad de Chile y en las maternidades chilenas participantes en el estudio colaborativo Latino Americano de malformaciones congénitas (ECLAMC) período 1991-1999.

BACKGROUND: ECLAMC is a registry, aimed to assess the incidence of congenital malformations, that started in 1967 and Chile incorporated to it in 1969. AIM: To report the incidence of cleft lip/palate, updated to 1999 in the University of Chile Maternity Hospital and other Chilean hospitals participating in the ECLAMC. PATIENTS AND METHODS: A review of the ECLAMC database that registers all births or stillbirths of more than 500 g. RESULTS: The incidence of orofacial cleft, at the University of Chile Maternity Hospital, in the period 1991-1999 was 17.8 per 10,000 (12.6 for cleft lip and 5.2 for cleft palate). The incidence in the rest of participating hospitals was 12.04 and 4.6 respectively. Males had a higher incidence of cleft lip and 80% of children with cleft palate, had other malformations, most of them as part of a syndrome (13 and 18 trisomy, holoproscencephalia, Pierre Robin, Apert en EE syndromes, anencephaly etc). In three of 12 children with cleft lip but without cleft palate, there was a relative with the same malformation. CONCLUSIONS: It is proposed that both entities, cleft lip with or without cleft palate and cleft palate without cleft lip, are two etiopathogenically different conditions.

[Disabling malformations in Chile. Latin American Cooperative Study of Congenital Malformations (ECLAMC), 1982-1997]. / Malformaciones invalidantes en Chile. Estudio ECLAMC, 1982-1997.

BACKGROUND: The ECLAMC (Estudio Colaborativo Latinoamericano de Malformaciones Congénitas) is an epidemiological surveillance program for congenital defects that operates in Chile since 1969. AIM: To communicate the frequency of disabling congenital defects in Chile in the period 1982-1997. MATERIAL AND METHODS: A review of the ECLAMC registry, choosing 12 congenital defects: amelia, limb amputations, limb reductions, arthrogryposis, hip luxation and subluxation, spina bifida, hydrocephaly, microcephaly, cephalocele, talipes equinovarus, Down syndrome and multiple abnormalities. RESULTS: In the study period, 283,403 births occurred and 7,917 newborns were malformed (7,654 born alive and 263 stillbirths). The congenital defects prevalence rates appeared higher in Chile than in other Latin American countries, specially among stillbirths. Among the studied maternity hospitals, the Clinical Hospital of the University of Chile, showed the higher prevalence of congenital defects. Rancagua and the Navy Hospital in Valparaiso have a high frequency of Down syndrome. Global rates in Chile and in the rest of ECLAMC for specific defects, do not have significant differences, except for hip subluxation, that has a lower incidence in Chile. CONCLUSIONS: The ECLAMC allows to have a good knowledge of the prevalence of congenital malformations in Latin America.

[Central nervous system malformations in a Clinical Hospital of Universidad de Chile and in Chilean maternity hospitals that participated in the Latin American Collaborative Study of Congenital Malformations (ECLAMC)]. / Malformaciones del sistema nervioso central en el Hospital Clínico de la Universidad de Chile y maternidades chilenas participantes en el Estudio Colaborativo Latinoamericano de Malformaciones Congénitas (ECLAMC).

BACKGROUND: In Chile, the rates of central nervous system congenital malformations at birth remain high, when compared with the rest of the world. AIM: To report the rates of central nervous system congenital malformations in Chilean hospitals. MATERIAL AND METHODS: Using the ECLAMC protocol, every malformed newborn or stillbirth, weighing more than 500 g at birth is registered using a standard protocol, and the next non malformed child of the same sex born in the same hospital is assigned as control. RESULTS: The rates of central nervous system congenital malformations are higher at the University of Chile Clinical Hospital than in the rest of Chilean hospitals or Latin American Hospitals. There are significantly higher rates of anencephalia in Concepcion and spina bifida in Valdivia, Rancagua and Concepcion. In the University of Chile Clinical Hospital, global annual rates have a negative slope of -0.0259 per 1000 born alive, with a correlation coefficient of -0.125 (p < 0.05). The slope is positive among children born alive, with an annual rate increase of 0.071. Among stillbirths, the slope is -0.47 per 1000 born alive. Sixty two percent of malformed children were female. Among children with neural tube defects, 30% had a malformed relative and, of these, 66% had the same malformation. CONCLUSIONS: Family clustering of neural tube defects, supports the influence of a genetic factor influencing their appearance.

[Anorectal congenital malformations and their preferential associations. Experience of the Clinical Hospital of the University of Chile. Period 1979-1999]. / Malformaciones congénitas anorrectales y sus asociaciones preferentes. Experiencia del Hospital Clínico de la Universidad de Chile. Período 1979-1999.

BACKGROUND: Anorectal atresia is a relatively frequent malformation in the newborn. According to the Latin American Collaborative Study for Congenital Malformations (ECLAMC), its frequency is 4.1 per 10,000 born alive. AIM: To determine the frequency of anorectal malformations at birth, and compare the figures with those of other maternity hospitals in Chile participating in ECLAMC, with the figures of the whole ECLAMC and with figures from other worldwide monitoring systems. PATIENTS AND METHODS: All births occurred in the University of Chile Clinical Hospital between January 1979 and August 1999, were reviewed. RESULTS: During the study period, 70,242 children were born, 4,486 had a malformation and 54 had an anorectal malformation (7.7 per 10,000 born alive). Fifty nine percent had other associated malformations (of the urinary tract in 42.5%, skeletal in 26% and cardiovascular in 18.5%). Five stillborn babies had other severe malformations. Twenty one children had a fistula. Forty three % were male, 39% female and 18% had ambiguous sex. When compared with normal controls, malformed newborns had a lower birth weight, lower gestational age and a higher mean maternal age, a higher frequency of metrorrhagia during the first trimester of pregnancy, a higher number of siblings with malformations and a higher degree of consanguinity among parents. CONCLUSIONS: The participation of recessive genes in the etiology of anorectal malformations is suggested.

[Prevalence of congenital malformations at birth and associated factors in Easter Island, Chile (1988-1998)]. / Prevalencia de malformaciones congénitas al nacer y factores asociados en Isla de Pascua, Chile (1988-1998).

BACKGROUND: Consanguinity plays an important role in the genetic etiology of congenital malformations. In Easter Island the degree of consanguinity could be higher than in continental Chile. Therefore the study of the prevalence of congenital malformations in this island seems worthwhile. AIM: To study the prevalence of congenital malformations at birth in Easter Island. MATERIAL AND METHODS: A review of personal and family features of all children born alive between 1988 and 1998 in the Rapa Nui Hospital of Easter Island. RESULTS: During the study period, 772 newborns were reviewed and 22 were found to have congenital malformations. Among the latter, birth weight fluctuated between 3001 and 4000 g and the male/female ratio was 0.54. No differences in maternal age between children with and without malformations was observed. Heart and circulatory malformations, hemangiomas and Down syndrome were the predominant malformations. CONCLUSIONS: The prevalence of congenital malformations at birth in Easter Island is similar to that of continental Chile. No neural tube defects were detected in this sample.

[Congenital malformations in the offspring of diabetic mothers]. / Malformaciones congénitas en los hijos de madres diabéticas.

The offspring of diabetic mothers have a 10 times higher frequency of congenital malformations and 5 times higher frequency of spontaneous abortions. Since the discovery of insulin, the prognosis of pregnancies has improved, both for the mother and the offspring. However, the prevalence of congenital malformations at birth has not decreased significantly. The embryological process that leads to anomalies in the offspring of diabetic mothers probably occurs between 6 and 8 weeks of gestation. According to animal experiments, hyperglycemia, ketones and free radicals may be involved in the genesis of malformations, but different strains of rats respond differently to these potential teratogenic agents. Possibly, a higher genetic susceptibility towards congenital malformations also plays a role in diabetic women. Therefore, although the intimate mechanism producing malformations in the offspring of diabetic women is not known, several strategies to decrease the prevalence of malformations in these women, such as the use of antioxidants, are being tested.

[Esophageal atresia and associated malformations]. / Atresia esofágica y malformaciones asociadas.

BACKGROUND: Survival of newborns with esophageal atresia and tracheoesophageal fistula has increased in the last years. AIM: To assess the prevalence of esophageal atresia and describe associated malformations in Chilean newborns. MATERIAL AND METHODS: All births occurring between January 1983 and June 1998 were studied. All malformed children were registered and the next non malformed born child was considered as control. RESULTS: During the study period, 50,965 births occurred and 3,336 malformed children were born. Eighteen (3 stillborn) had esophageal atresia with a rate of 3,53 per 10,000 born alive. Overall survival was 73%. Survival among children classified in Waterson groups A and B was 100% and 50% among those classified in group C. Seventy two percent had associated malformations, being congenital cardiopathies and skeletal malformations the most frequent. VACTERL association was found in 44% of children. All stillborn children had other severe malformations. When compared to controls, malformed children had a lower weight, a lower gestational age, their mothers had a higher age, a higher frequency of relatives with malformations and a higher frequency of maternal diseases during the first trimester of pregnancy. CONCLUSIONS: The rate of esophageal atresia found in this study is similar to that reported in other Chilean obstetrical units as part of the Latin American Study of Congenital Malformations (ECLAMC).

[Congenital malformations in twins]. / Malformaciones congénitas en gemelos.

BACKGROUND: A higher prevalence of congenital malformations among twins than among single has been reported in the literature. AIM: To study the incidence of congenital malformations in twins in the maternity hospital of the University of Chile in the period 1983-1997. MATERIAL AND METHODS: As part of the Latin American Collaborative Study of Congenital Malformations, every newborn in the maternity hospital was examined by a neonatologist and congenital malformations were recorded in a special file. RESULTS: In the study period there were 48.663 deliveries of single pregnancies and 448 deliveries of twin pregnancies, giving birth to 886 twins borns alive and 17 stillbirths (1.9% mortality). Of these, there were 423 twins, 17 triplets, a sextuple delivery and two siamese. Seven point one percent of twins born alive and 6.5% of single newborns had a congenital malformation. The prevalence of malformations in twins and single stillbirths was 35.2 and 17.2% respectively (p < 0.04). In four pairs and siamese newborns, malformations typical of monozygotic twins were present, such as an acardiac fetus with Trap sequence, a papyraceous fetus and two with hydroanencephaly. Twelve twins had malformations attributable to uterine compression. CONCLUSIONS: This study did not find a higher frequency of malformations comparing twins with single babies born alive, but in stillbirths there was a significant difference between single and twin stillbirths (7.1% versus 35.2%, respectively, p < 0.05).

[Incidence of Down syndrome at a University Hospital Maternity of Chile. A 25-year record: 1972-1997]. / Incidencia del sindrome de Down en la maternidad del Hospital Clínico de la Universidad de Chile. Un registro de 25 años: 1972-1997.

BACKGROUND: The main function of ECLAMC (Latin American Congenital Malformations Collaborative Study) is to monitor congenital malformations in Latin American countries. Down syndrome, due to its medical and social importance, has received special concern. AIM: To measure the rates of incidence of Down syndrome in an University hospital maternity and to compare demographic variables of children born with the syndrome and healthy children. MATERIAL AND METHODS: Between 1990 and 1997, all children born with Down syndrome were registered, and the next healthy newborn of the same sex was considered as control. Also, using previous registers, the prevalence of newborns with Down syndrome and the mean maternal age from 1972 to 1997 were compared using regression equations. RESULTS: During the 7 years study period, 53 Down syndrome patients were born (66% female, two stillbirths). Thirty percent had congenital heart disease, forty seven had a regular 21 trisomy, one had a Robertsonian translocation, two had mosaicism for 21 trisomy, one was 48, XXX + 21 and one was 48, XXY + 21. Compared to controls, these children had lower gestational age and birth weight, mean maternal and paternal ages were higher, previous abortions were more frequent and the intergenesic period more prolonged. From 1972 to 1997, both the birth rate of Down syndrome and mean maternal age increased significantly with slopes of 0.13 years of age per year and 0.05/1000 born alive per year, respectively. Comparing both rates, the prevalence rate of Down syndrome increased in 0.31 per 1000 born alive per year of increment in maternal age. Father's age had no influence on this prevalence. CONCLUSIONS: In the period 1990-1197, a higher prevalence rate of Down syndrome than in previous periods in the same maternity, was found. The influence of maternal age on this prevalence was clearly established.

[Association between maternal heterozygosity for five blood groups and reproductive success]. / Asociación entre heterocigocidad materna para cinco grupos sanguíneos y éxito reproductivo.

BACKGROUND: In man, blood groups are polymorphic genetic systems. Maternal fetal incompatibility phenomena should lead to an elimination rather than a maintenance of these polymorphisms. A possible mechanism that could explain the persistence of these polymorphisms in natural populations is a selective reproductive advantage of heterozygous individuals. AIM: To explore the relationship between maternal heterozygosity for five blood groups and some obstetrical variables related to gestational success. MATERIAL AND METHODS: Using a case control design, to every mother giving birth to a malformed child a consecutive mother, whose offspring was normal, was assigned as control. All women were typified for ABO, Rh, Kidd, MNSs and Duffy blood groups. RESULTS: Two hundred two women were studied. There was only one stillbirth, born from a heterozygous mother for all analyzed loci. Mothers that were heterozygous or homozygous for all loci had a higher frequency of malformed children. Women homozygous for all loci had a higher frequency of living offspring than the rest of the sample. CONCLUSIONS: Heterozygous mothers for these genetic systems have a reproductive disadvantage.

[Urinary tract malformations in newborns at the Clinical Maternity Hospital of the University of Chile]. / Malformaciones del aparato urinario en recién nacidos de la Maternidad Hospital Clínico de la Universidad de Chile.

BACKGROUND: The prevalence of urinary malformations at birth is steadily increasing, probably due to the availability of better diagnostic techniques. AIM: To assess the prevalence of renal agenesis, hidroureteronephrosis and polycystic kidney at birth in the obstetric wards of the University of Chile Clinical Hospital. PATIENTS AND METHODS: As a part of the Latin American Collaborative Study of Congenital Malformations, 54.039 consecutive births at the Maternity, between January 1982 and December 1997, were studied. RESULTS: Eighty three newborns had urinary tract malformations (15.3/10,000). Fourteen (2.6/10,000) had renal agenesis, 34 (6.3/10,000) had hidroureteronephrosis and 35 (6.5/10,000) had polycystic kidney. Eleven percent of these children were stillbirths and 35% died in the first days of life. Fifty six percent were male, 34% female and 10% had ambiguous sex. Mean birth weight was 2750 g, mean gestational age was 35.4 weeks and mean maternal age was 28 years old. Twenty three percent of mothers had a history of previous abortions, 8% had a history of stillbirths and 10% a history of metrorrhagia during the first trimester of pregnancy. Twenty five percent of children had a relative with a malformation and 48 children had other associated malformations such as pulmonary hypoplasia, external malformations caused by extreme oligoamnios or internal malformations such as utereral, urinary bladder; uretral or external genitalia agenesis. CONCLUSIONS: The prevalence of urinary malformations in this hospital was higher than in other hospitals participating in the collaborative study. This difference could be due to an under registration of malformations in other hospitals.

[Association between Kidd blood group and congenital malformations]. / Asociación entre grupo sanguíneo kidd y malformaciones congénitas.

BACKGROUND: Since the discovery of blood groups, an association between these genetic polymorphisms and pathological phenotypes has been searched, looking for factors involved in the pathogenesis of diseases or biological population mechanisms that maintain these polymorphisms. In previous reports, we have described some associations between erythrocytic genetic marker segregation and the presence of congenital malformations. AIM: To explore the association between Kidd blood group and congenital malformations. PATIENTS AND METHODS: One hundred twenty two malformed newborns and their mothers and 136 normal newborns, seen at the Clinical Hospital of the University of Chile, were studied. RESULTS: Kidd blood group segregation distortions were found among male malformed newborns, that were not present in normal newborns. Among mothers of both groups of newborns, a paucity of heterozygous for this system was found. CONCLUSIONS: The association found between a blood group and congenital malformations, allows to state that malformed children have a different genetic background, when compared to normal children.

[Incidence of congenital malformations in 10 Chilean maternity hospitals that participate in the ECLAMC. Comparison of 3 periods (1971-1977, 1982-1988, 1989-1994)]. / Incidencia de las malformaciones congénitas en 10 maternidades chilenas participantes en el ECLAMC. Comparación de tres períodos (1971-1977, 1982-1988, 1989-1994).

BACKGROUND: The Latin American Collaborative Study of Congenital Malformations is an epidemiological surveillance system for congenital malformations that operates in 11 Latin American Countries. AIM: To report the incidence of congenital malformations in 8 Chilean maternity hospitals participating in this study, between 1989 and 1994. MATERIAL AND METHODS: During the study period, 133,564 newborns and 1,196 stillbirths from 8 Chilean maternity hospitals were examined. These results were compared with those of a similar survey performed in 1982-1988. RESULTS: The proportion of stillbirths in the study period was 0.88%. There were 3,268 malformed newborns (2.42%) and 125 malformed stillbirths (10.45%). These proportion of malformations among newborns were lower and among stillbirths were higher than those reported for the rest of Latin American countries. When comparing the results with the previous survey, a reduction in the proportion of malformations among newborns was observed. However, in all Latin American countries, the prevalence of malformations in newborns and stillbirths increased in this period. In the period 1969-1995, in one Chilean hospital, maternal ages and the proportion of congenital malformation showed parallel and rising curves. CONCLUSIONS: This survey shows some differences in the prevalence of congenital malformations, when the figures are compared with other Latin American countries and with previous surveys.