Gastrosquisis: ¿una pandemia con tasas en aumento? Experiencia del estudio colaborativo latino americano de malformaciones congénitas (ECLAMC) en Chile. Período 1982-2014 / Gastroschisis: A pandemic with increasing rates? ECLAMC experience in Chile 1982-2015

Introducción: Numerosas publicaciones han alertado sobre el aumento sostenido de las tasas de prevalencia al nacimiento de gastrosquisis en todo el mundo, catalogado este hecho como una «pandemia¼ fuertemente asociada a edad materna baja. Objetivos: Comprobar si en Chile se ha producido también un aumento significativo de la tasa de prevalencia al nacimiento de gastrosquisis y si se relaciona con edad materna baja. Pacientes y método: Se usó la base de datos ECLAMC de 26 hospitales chilenos participantes. Las tasas de prevalencia entre hospitales y las categorías de edad materna se compararon con prueba de Chi cuadrado o prueba exacta de Fisher. Se estudió la serie temporal mediante comparación de tendencias lineales, usando comparaciones de medias vía t-test y Wilcoxon-test. Resultados: En el período 1982-2014 nacieron 721.901 niños, entre los que se encontró 107 casos de gastrosquisis (1,49/10.000), el 75,7% de ellos eran hijos de mujeres menores de 25 años. El promedio de edad materna de los casos fue de 21,6 años, y el promedio nacional es cercano a 28 años, según el Ministerio de Salud. A partir de 1995 esta tasa mostró una tendencia ascendente significativamente distinta de cero (p = 0,00714), con un aumento de 0,1591 cada año. Este incremento fue alrededor del 300% entre 1995 y 2014, respecto del período anterior (p < 0,00001). Conclusión: En Chile se ha producido un aumento significativo de las tasas de gastrosquisis después del año 1995, y esta anomalía se asocia fuertemente con baja edad materna.

Introduction: Several communications have reported a significant increase in the prevalence of gastroschisis at birth in the last three decades. In many Countries it is referred to as "a pandemic strongly associated to low maternal age". Objective: To verify if there has been a significant increase in the prevalence of gastroschisis at birth in Chile, and if this rate is associated with a low maternal age. Patients and methods: The study was performed using the ECLAMC data base from 26 Chilean Hospitals. Comparison between prevalence rates and maternal age categories were made using the X² test or Fisher exact Test. The time series was studied comparing average tendencies using the Student t test and Wilcoxon-test. Results: There were 721,901 newborns in the period 1982-2014, among which 107 were diagnosed with gastroschisis (1.48/10,000). Around three-quarters (75.7%) of them were born from mothers younger than 25. The mean maternal age was 21.6 years in mothers of children with gastroschisis, while the mean maternal age of all mothers from Chile was almost 28 years old. The gastroschisis prevalence at birth rate was constant at around 1/10,000 until 1994. From 1995 this rate has a significant increasing tendency of 0.1591 by year (P = .00714). This increase is about a 300% on average for the 1995-2014 period, compared with the previous one (P < .00001). Conclusion: There has been a significant increase in the gastroschisis prevalence at birth in Chile from 1995, and this anomaly is associated with a low maternal age.

ECLAMC: 41 años de vigilancia de la holoprosencefalia en Chile. Período 1972-2012 / Frequency of holoprosencephaly in Chile

Background: Holoprosencephaly is a structural anomaly of the brain that consists in a defect of the prosencephalon development that leads to face and neurological defects of variable intensity. Aim: To estimate holoprosencephaly prevalence at birth. Patients and Methods: All cases of holoprosencephaly, born alive or stillbirths, registered in the 15 Chilean Hospitals of the Latin American Collaborative Study of Congenital Malformations (ECLAMC) between 1972 and 2012, were studied. Craniofacial and other anomalies found in newborns affected by holoprosencephaly are described. Results: Fifty five cases of holoprosencephaly (58% males) were found among the 798.222 registered births (rendering a prevalence at birth of 0.69 per 10.000 newborns). The most common cranial defect was medial cleft lip with cleft palate (27.3%), bilateral cleft lip (11%) or both (38.2%), cyclopia (14%), single nostril (10.9%) and proboscis (9.1%). Eleven percent cases had a trisomy 13. A slight increase in prevalence over time was observed. Conclusions: Holoprosencephaly has a low frequency in Chile and is associated to trisomy 13. The increase in prevalence could be explained by a better prenatal diagnosis (ultrasonography).

Prevalencia de malformaciones congénitas en hijos de madres mayores de 34 años y adolescentes: Hospital Clínico de la Universidad de Chile, 2002-2011 / prevalence rate of congenital malformations among newborn of teenagers mothers and older than 34 years old: Hospital Clínico de la Universidad de Chile, 2002-2011

Antecedentes: Las madres mayores de 34 años han aumentado en Chile. La mayor edad materna aumenta el riesgo de malformaciones congénitas (MFC) Objetivos: Determinar la tasa de prevalencia de MFC entre adolescentes y mayores de 34 años. Método: Se utilizó la base de datos de la Maternidad del Hospital Clínico Universidad de Chile (2002-2011). Se estudió todos los nacimientos, vivos, mortinatos y malformados de 500 gramos o más, de madres menores de 20 y mayores de 34 años. Se calculó y comparó las tasas de prevalencia al nacer de todas las malformaciones de cada grupo etario. Resultados: Hubo 15.636 nacimientos, 0,98 por ciento fueron mortinatos, 7,5 por ciento hijos de madres menores de 20 años y 27,7 por ciento de mayores de 34 años. La tasa global de MFC fue 8,8 por ciento; 7 por ciento en menores de 20 años y 9,6 por ciento en mayores de 34 años (p=0,007). Síndrome de Down fue 12 veces más frecuente en los hijos de madres mayores de 34 años que en las adolescentes. Las mayores de 34 años presentaron significativamente más mortineonatalidad en sus hijos malformados que las adolescentes, pero menor frecuencia de bajo peso, menor consumo de tabaco, alcohol y mariguana. Conclusión: El grupo de madres mayores de 34 años es significativamente diferente al grupo de adolescentes, tanto en prevalencia de MFC como en mortalidad neonatal de malformados, bajo peso al nacer y hábitos de vida...

Background: Mothers older than 34 years have increased trend in Chile. The maternal age increases the risk of congenital malformations (CMF). Objectives: Determine the prevalence rate of CMF among newborn of teenagers mothers and older than 34 years old. Method: We used the database of the Maternity Hospital, University of Chile (2002-2011). We studied all births, live, stillbirths and malformed newborn of 500 grams or more, from mothers under 20 and over 34 years. We calculated and compared the birth prevalence rates of all malformations for each age group. Results: There were 15,636 births, 0.98 percent were stillbirths, 7.5 percent children of mothers under 20 years and 27.7 percent older than 34 years. The overall rate of CMF was 8.8 percent; 7 percent in under 20 years and 9.6 percent in mothers over 34 years (p=0.007). Down syndrome was 12 times more common in children of mothers older than 34 years than in adolescents. The older than 34 years had significantly more neonatal mortality in malformed children than adolescents, but lower frequency of low birth weight, lower consumption of snuff, alcohol and marijuana. Conclusion: The group of mothers older than 34 years is significantly different from the group of teenagers, both in prevalence of CMF as neonatal mortality, low birth weight and lifestyle habits...

Malformaciones congénitas en hijos de madres con diabetes gestacional / Congenital malformations among offspring of diabetic women

Background: The risk of congenital malformations is two to three times higher among women with diabetes mellitus before pregnancy. Gestacional diabetes is emerging as a risk factor for malformations. Aim: To study the rate and type of congenital malformations among offspring of women with pre-gestational or gestational diabetes. Material and methods: A search in the databases of the Collaborative Latin American Study for Congenital Malformations and of the Neonatology Unity of The University of Chile Clinical Hospital. All births from January 1998 through June 2004 were investigated. Results: In the study period, 13,965 births occurred, of which 0.7% were stillbirths and 8.1% had malformations. A total of 295 women (2.1%) had diabetes (gestational diabetes in 1.8% and pre gestational diabetes in 0.3%). The prevalence of congenital malformations was 14% and 18.3% among offspring of mothers with pre-gestational and gestational diabetes, respectively (p=NS). The prevalence of congenital malformations among offspring of non diabetic women was 7.9% (p <0.001 with respect to diabetic women). Major malformations were found in 83% and 70% of malformed offspring of women with pre-gestational and gestational diabetes, respectively. Conclusions: Pregnant women with pre-existing or gestational diabetes have a higher risk of giving birth a child with malformations.

Malformaciones congénitas y patología crónica de la madre: estudio ECLAMC 1971-1999 / Association between congenital malformations and chronic diseases of the mother

Background: Several maternal diseases, such as diabetes mellitus or high blood pressure, are associated with a higher risk for fetal or neonatal problems. Aim: To study the association between chronic diseases of the mother and congenital malformations. Material and methods: Review of the records of the Latin American Collaborative Study of Congenital Malformations (ECLAMC) at the University of Chile Clinical Hospital. A sample of 383 mothers with a chronic disease was compared with 297 healthy mothers. The presence of congenital malformations in the newborns was studied. The odds ratio (OR) of a mother to have a child with a congenital malformation was calculated. Results: Mothers with bronchial asthma, diabetes mellitus, hypertension and hypothyroidism had an OR over 1 of having a child with a congenital malformation. No association between maternal obesity and offspring malformations was observed. Offspring of diabetic mothers had 8.95 times more probabilities of having a major malformation and 4.95 times more probabilities of having a minor defect. Conclusions: Offspring of mothers with diabetes mellitus, bronchial asthma, hypertension or hypothyroidism have a higher risk of presenting a congenital malformation, when compared with offspring of healthy mothers

Malformaciones congénicas del sistema digestivo: maternidad Hospital Clínico de la Universidad de Chile: período 1991-2001 / Frequency of digestive system congenital malformations detected at the University of Chile hospital in the period 1991-2001

There were 26,617 births attended at the University of Chile Clinical Hospital, of which 0.63 percent were stillborn. A frequency of malformations of 7.2 per born alive and of 22.1 per stillborn was detected in this population. Aim: To report the frequency of digestive system congenital malformations in this population. Material and methods: Analysis of data from the births that occurred at the University of Chile Hospital, that was gathered using codified form for the Latin American Collaborative Study for Congenital Malformations. Results: Ninety seven digestive congenital malformations were detected, with a rate of 26.4 per 10,000 born alive and 12.2 per 10,000 stillborn. Diaphragmatic hernia was the most frequent malformation found, followed by imperforated anus, onphalocele and esophageal atresia. There was a secular increase in the frequency of these malformations. Conclusions: The frequency of digestive system malformations is higher than in the rest of hospitals participating in the Latin American Collaborative Study for Congenital Malformations

Malformaciones del sistema nervioso central en el Hospital Clínico de la Universidad de Chile y maternidades chilenas participantes en el estudio colaborativo lationamericano de malformaciones congénitas, ECLAMC / Central nervous system malformations in Chilean hospitals participating in the Latin American collaborative study of congenital malformations, 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 per cent had a malformed relative and, of these, 66 per cent had the same malformation. Conclusions: Family clustering of neural tube defects, supports the influence of a genetic factor influencing their appearance

Malformaciones congénitas en Chile: un problema emergente período 1995-1999 / Congenital malformations in Chile: an emergent problem at 1995-1999 period

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. Anencephalia 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

Sexo ambiguo: prevalencia al nacimiento en la maternidad del Hospital Clínico de la Universidad de Chile / Ambiguous sex: prevalence at birth in a university obstetric service in Santiago, 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 percent 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 percent) and cardiovascular systems (60.7 percent). 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 10000)

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 / Incidence of orofacial cleft at Universidad de Chile maternity hospital and other hospitals participating in the Latin American collaborative study of congenital malformations, ECLAMC

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 10000 (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 percent 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

Malformaciones invalidantes en Chile: estudio ECLAMC 1982-1997 / Disabling congenital defects in Chile: 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

Estudio de tres loci hipervariables en población mixta chilena / Study of 3 hypervariable loci in a mixed chilean population

Background: Genetic markers are useful to study evolution parameters in populations and to determine kinship. Aim: To characterize three short tandem repeat loci in a sample of Chilean subjects and compare them with Caucasian and Hispanic populations. Material and methods: Three hundred ninety three unrelated subjects that were sent for genetic studies from courts of justice, were studied. The loci FESFPS, F13A01 and vWA in blood samples, were typified amplifying DNA by polymerase chain reactions. Results: The three studied loci were highly polymorphic. F13A01 and FESFPS were in Hardy-Weinberg genetic equilibrium. A significant excess of heterozygotes was detected for vWA locus. There were no differences in allele frequencies, according to ethnic origins of last names. Allele frequencies for F13A01 and vWA loci were similar to those of Hispanic populations of Unites States and FESFPS loci was different. Conclusions: All three loci had a high efficiency for genetic identification tests according to the estimated a priory exclusion probability

Malformaciones congénitas anorrectales y sus asociaciones preferentes: experiencia del Hospital Clínico de la Universidad de Chile, período 1979-1999 / Anorectal congenital malformations and their associations in a Chilean University Hospital between 1979 and 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 percent, skeletal in 26 percent and cardiovascular in 18.5 percent). Five stillborn babies had other severe malformations. Twenty one children had a fistula. Forty three percent were male, 39 percent female and 18 percent 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

Prevalencia de malformaciones congénitas al nacer y factores asociados en Isla de Pascua, Chile: 1988-1998 / Prevalence of congenital malformations and associated factors in Easter Island, Chile

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

Análisis de paternidad utilizando cuatro marcadores de DNA amplificados mediante la reacción en cadena de polimerasa / Paternity analysis using 4 DNA markers amplified by polymerase chain reaction

Background: DNA typing in forensic analysis is a useful tool to analyze paternity due to its high discrimination power. Aim: To report the experience of Servicio Medico Legal in Santiago, resolving cases of dubious paternity. Subjects and methods: Four highly polymorphic loci, amplified by polymerase chain reactions, were analyzed in 153 cases of uncertain paternity. The paternity index was calculated for each case. Results: The four genetic markers analyzed provided an exclusion probability of 0.933 for the general population in Santiago. Thirty seven cases were excluded as parents. In 31 cases, the paternity index ranged from 19 to 100, considered as probable paternity and 77 cases had an index of over 100, considered as almost certain paternity. Eight cases had an index between 0.5 and 19, considered as inconclusive. All loci met Hardy-Weinberg expectations and their frequencies were similar to other data from people living in Santiago. Conclusions: The use of these genetic markers proved to be very useful, reliable and with a high exclusion power for paternity analysis

Atresia esofágica y malformaciones asociadas / Esophageal atresia and associated malformations

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 percent. Survival among children classified in Waterson groups A and B was 100 percent and 50 percent 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 percent 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)

Malformaciones congénitas en gemelos / Congenital malformations in twins

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 percent 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 percent of single newborns had a congenital malformation. The prevalence of malformations in twins and single stillbirths was 35.2 and 17.2 percent 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 percent versus 35.2 percent, respectively, p <0.05)

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

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