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OBJECTIVES: To evaluate the association between absence of nasal bone on ultrasound and Down syndrome in fetuses at 11-14 weeks of pregnancy. METHODS: One hundred and ninety-four consecutive fetuses from singleton pregnancies undergoing chorionic villi sampling (CVS) were evaluated by transabdominal ultrasound. A sagittal view of the fetal face was obtained and the absence or presence of nasal bone was recorded and correlated with the fetal karyotype. RESULTS: A successful view of the fetal profile was possible in 183 of 194 (94%) fetuses. The nasal bone was absent in three of five fetuses with Down syndrome, and in one of 175 (0.6%) chromosomally normal fetuses. CONCLUSION: Absence of nasal bone by first trimester ultrasound was significantly associated with Down syndrome. When a proper view of the fetal face was obtained, the nasal bone was visible in more than 99% of karyotypically normal fetuses.

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This investigation analyzed social and demographic characteristics of women having an unwanted or mistimed pregnancy (unintended pregnancies at the current time) in South America. A sample of 5135 women having had a normal non-malformed live-born infant were interviewed immediately postpartum at 18 hospitals participating in the Latin American Collaborative Study of Congenital Malformations (Spanish acronym: ECLAMC). Half (2568/5135 = 50%) reported that their pregnancies had been unintended, and, of those, 59.3% (1522/2568 = 59.3%) declared that they were trying to avoid conception. The latter group (n = 1522) was the main sample for this study. Patients were asked about their knowledge of when during the menstrual cycle conception is most likely to occur, their biomedical and social characteristics, the type of contraceptive methods used, their opinion of reasons for contraceptive failure, and their reasons for not using contraceptive methods. Among women with unintended pregnancies who attempted to avoid conception, only 61.6% were using contraceptive methods. Reasons given for not using contraceptives included health problems, lack of knowledge and lack of access to contraception. Women with unintended pregnancies who had not attempted to avoid conception were younger, often primigravid, less educated, and less knowledgeable concerning when during the cycle pregnancy is most likely to occur. Thus, reproductive health policies should be aimed at this target group.

PIP: This study analyzes the social and demographic characteristics of women having an unwanted or unintended pregnancy in South America between 1992 and 1994. The study was conducted among 5135 women who had a normal non-malformed live-born infant and were interviewed at 18 hospitals participating in the Latin American Collaborative Study of Congenital Malformations. Patients were asked about their knowledge of when conception is most likely to occur during the menstrual cycle, their biomedical and social characteristics, the type of contraceptive methods used, their opinion and reasons for contraceptive failure, and their reasons for failing to use contraceptive methods. Results indicate that 50% of the respondents had unintended pregnancies, and about 59% declared that they were trying to avoid conception. However, among women with unintended pregnancies who attempted to avoid conception, only 61.6% were using contraceptive methods. Reasons for failure to use contraceptives include health problems, lack of knowledge, and lack of access to contraception. Meanwhile, women with unintended pregnancies who had not attempted to avoid conception were younger, often primigravid, less educated, and less knowledgeable concerning the likelihood that pregnancy will occur during menstrual cycle. This study implies that reproductive health policies should be aimed at this target group.

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Unintended pregnancies are accepted as associated with social, maternal and perinatal risks, but few data exist in South America. In a selected network of hospitals participating in the ECLAMC (Spanish acronym for Latin American Collaborative Study of Congenital Malformations), the frequency of unintended pregnancies was 49.8% in 5155 mothers of normal liveborns, as interviewed in the post-partum period (1992-1994). Compared with the intended pregnancy group, these mothers were more frequently multiparous, conceived easily, had a surprisingly higher mean maternal age, lower educational level, and Black ancestors. The frequency of mistimed pregnancies was the highest among primiparae. No adverse perinatal outcome could be found with regard to low birthweight (< 2500 g), prematurity (< 37 weeks), and early neonatal death. The rates of Caesarean delivery, twinning and sex ratio were similar in intended and unintended groups. Logistic regression analysis showed that maternal education could be a confounding factor associated with other maternal variables. The rate of unintended pregnancies in the present study is significantly higher than that described for other regions. Knowledge of the characteristics of women experiencing unintended pregnancies would allow proper public health strategies.

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Obstetricians' epidemiological knowledge and their awareness of associated risk factors are essential for the primary prevention of birth defects. Screening and early diagnosis of congenital malformations is an expanding field in general obstetrics. Cardiac defects are the most frequent type of congenital malformation, and early detection is possible.

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Desde el episodio de la talidomida en los 50, un número creciente de medicamentos y agentes químicos han sido imputados como agentes causales en la producción de teratogénesis y toxicidad fetal, situación que es conocida cada vez más por la opinión pública. Actulamente se recomienda evitar el uso de medicamentos durante el embarazo, mientras que aquellos que sean prescriptos necesariamente deben ser evaluados con respecto a sus potenciales beneficios y riesgos, tanto para la madre como para el feto. No obstante, distintos estudios indican que entre el 40 por ciento y el 90 por ciento de las mujeres embarazadas están expuestas a uno o más medicamentos durante el embarazo. Estos estudios están realizados sobre poblaciones con características socioculturales diferentes a la población hospitalaria latinoamericana, por lo que los resultados no son extrapolables. Una gran cantidad de fármacos se usan cuando se piensa que ésto potencialmente beneficiará a la madre y que este fármaco se encuentra en el mercado con suficiente tiempo para que se hubiesen producido un número importante de exposiciones no intencionadas. Esto puede producir en los médicos una falsa sensación de seguridad, especialmente con respecto a los medicamentos que producen efectos infrecuentes como los defectos congénitos. Los programas de monitoreo de defectos congénitos son una fuente importante de información sobre exposición a agentes ambientales y defectos presentes al nacimiento. Estos programas vigilan la variación de la frecuencia de base de defectos congénitos para detectar la aparición de nuevos teratógenos, y son útiles para dar algunas pistas en la asociación entre exposición a madicamentos y malformaciones. El objetivo de este trabajo es el de establecer la frecuencia y tipo de medicamentos a la que está expuesta la población en nuestro medio, y describir algunos de los datos contenidos en la base de datos del ECLAMC sobre exposición a medicamentos de uso común, usando métodos simples para buscar asociaciones entre medicamentos y malformaciones (AU)

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Desde el episodio de la talidomida en los '50, un número creciente de medicamentos y agentes químicos han sido imputados como agentes causales en la producción de teratogénesis y toxicidad fetal, situación que es conocida cada vez más por la opinión pública. Actulamente se recomienda evitar el uso de medicamentos durante el embarazo, mientras que aquellos que sean prescriptos necesariamente deben ser evaluados con respecto a sus potenciales beneficios y riesgos, tanto para la madre como para el feto. No obstante, distintos estudios indican que entre el 40 por ciento y el 90 por ciento de las mujeres embarazadas están expuestas a uno o más medicamentos durante el embarazo. Estos estudios están realizados sobre poblaciones con características socioculturales diferentes a la población hospitalaria latinoamericana, por lo que los resultados no son extrapolables. Una gran cantidad de fármacos se usan cuando se piensa que ésto potencialmente beneficiará a la madre y que este fármaco se encuentra en el mercado con suficiente tiempo para que se hubiesen producido un número importante de exposiciones no intencionadas. Esto puede producir en los médicos una falsa sensación de seguridad, especialmente con respecto a los medicamentos que producen efectos infrecuentes como los defectos congénitos. Los programas de monitoreo de defectos congénitos son una fuente importante de información sobre exposición a agentes ambientales y defectos presentes al nacimiento. Estos programas vigilan la variación de la frecuencia de base de defectos congénitos para detectar la aparición de nuevos teratógenos, y son útiles para dar algunas pistas en la asociación entre exposición a madicamentos y malformaciones. El objetivo de este trabajo es el de establecer la frecuencia y tipo de medicamentos a la que está expuesta la población en nuestro medio, y describir algunos de los datos contenidos en la base de datos del ECLAMC sobre exposición a medicamentos de uso común, usando métodos simples para buscar asociaciones entre medicamentos y malformaciones

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OBJECTIVE: Limb reduction defects were considered as possible indicators of environmental teratogenesis; it was suggested that also invasive prenatal procedures could increase the risk for limb reduction defects. The purpose of this work is to give a baseline frequency for limb reduction defects, using data from a population not exposed to prenatal diagnosis procedures. DESIGN: Using data collected in the period 1967 to 1992 within the frame of the Latin American Collaborative Study of Congenital Malformations which clinically examined 2,917,074 newborn infants, a total of 1715 with limb reduction defects were found. All cases were classified and analysed in 25 categories. Geographic differences in recorded rates were tested by chi 2 for homogeneity. Secular trends were analysed using chi 2 test for linear trends. RESULTS: The overall birth prevalence rate of limb reduction defects among liveborn infants was 4.91(per 10,000 births) (3.05 for isolated and 1.85 for associated cases). For stillbirths, the total prevalence was 26.73/10,000 (5.53 for isolated and 21.20 for associated cases). The inclusion of the brachydactylies increased those figures to 5.55/10,000 (3.39 for isolated and 2.16 for associated cases), and 27.42, respectively, (5.53 for isolated and 21.89 for associated cases). When isolated and associated cases were considered together, a geographic heterogeneity was found in pre-axial limb reduction defects; there was also some heterogeneity for amputations. A maternal age effect was found for the isolated hypoplasias. Standardising by maternal age, the overall prevalence of limb reduction in liveborn infants was 5.66 per 10,000 (95% CI = 5.38-5.93). An increasing trend was suggested by the isolated form of distal amputations which involved hands, feet, or digits. CONCLUSIONS: Our data suggest that clustering limb reduction defects in wide groups as transverse and longitudinal may lead to heterogeneous entities. When a possible association is suspected, it would be preferable to present and analyse data in the most discriminant form available. Due to the maternal age effect, it would be advisable to standardise the rates of transversal limb reduction defects by this variable.

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We report on a case of Fryns' syndrome diagnosed prenatally in a woman with no family history of this disorder. A computerized database was used for the differential diagnosis. Intensive perinatal care resulted in prolonged survival, which is unusual in individuals with Fryns' syndrome. This case provides further delineation of the developmental course in patients with this condition.

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OBJECTIVE: To look for associations between previous fetal loss and fetal malformation or low birthweight in a subsequent pregnancy. DESIGN: A case-control study with place of birth, time and sex matched controls. SETTING: 72 South American maternity hospitals. SUBJECTS: 18,534 malformed, 1150 non-malformed babies of low birthweight and 16,394 controls. All babies were from mothers with at least one previous pregnancy. MAIN OUTCOME MEASURES: Frequency of stillbirths and miscarriages in the previous pregnancy and outcome of the index pregnancy. RESULTS: Multiple malformation, Down's syndrome, anencephaly, spina bifida, pes equinovarus, congenital dislocation of the hip and low birthweight are associated with previous fetal loss. CONCLUSION: A miscarriage or a stillbirth in a previous pregnancy should be taken into account when the risk of malformations or low birthweight in a subsequent pregnancy is assessed.

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During the years 1975-1987, 1,364 cytogenetic studies were performed in 682 couples with history of adverse pregnancy outcome. Thirty-six balanced translocations were detected, 24 (3.5%) in women and 12 (1.7%) in men. Before 1982, all 234 couples studied had 2 or more spontaneous abortions with unknown pedigrees, with an incidence of 6.8% of balanced translocations. During 1982-1987, complete pedigree analysis was performed on a subset of 448 couples, who were then classified into 3 groups. Group I; 321 couples with 2 or more spontaneous abortions, but no other adverse outcome; group II; 37 couples with at least one or more spontaneous abortions plus a malformed child or stillbirth; and group III; 90 couples with one or more spontaneous abortions plus a sib having at least a malformed child or repetitive spontaneous abortions. The incidence of balanced translocations in these 3 groups was 2.8%, 5.4%, and 10.0%, respectively. When group III was compared with group I, the frequency of translocations was significantly different (P less than 0.02). Robertsonian translocations were predominantly detected in women, raising the possibility that prezygotic failure producing primary sterility may occur in men with such translocations.

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Fetal death is essential to evaluate perinatal outcome. Accurate stillbirth rate however is difficult to obtain; this is especially so in developing countries. Current information was obtained through a clinical-epidemiological study, ECLAMC, during the 1982-1986 period for a total sample of 869 750 births in 102 hospitals belonging to 11 Latin American countries. The overall stillbirth rate was 2.0%, the highest being in Bolivian (4.4%) and the lowest in Chilean hospitals (0.9%). In all countries there was a high mortality rate among male fetuses. The incidence of stillbirth in multiple pregnancies almost doubled that for singletons. A steady increase with increasing maternal age was observed. The proportion of all births in mothers 35 years of age or older was 10.1%, while the stillbirth proportion among all stillbirths in the same maternal age group was 18.8%. As expected, a higher fetal mortality rate (10.7%) was found in the low birthweight group (less than or equal to 2500 g) than in the group with birthweight greater than 2500 g (0.6%). One out of ten births occurred in the former group. A striking difference was observed in the stillbirth rate between hospitals with free obstetrical care (2.5%) and those in which any type of payment was required (1.4%). Although socioeconomical factors are probably the main factors responsible for fetal death, increased maternal age and a high incidence of low birthweight also contributed greatly to fetal mortality. These risk factors for fetal mortality should be the target of public health actions in these countries.

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La disgenesia gonadal producto de una anomalía en la diferenciación de la gónada primitiva puede estar asociada tanto a factores genéticos como ambientales. En los últimos años el aumento en el conocimiento del primero de estos mecanismos etiológicos así como del proceso normal de diferenciación, desarrollo y mantenimiendo de la gónada, junto con una mayor precisión diagnóstica de este cuadro, ha posibilitado establecer el origen del mismo en la mayoría de los casos, permitiendo evaluar el pronóstico y posibles recursos terapéuticos. Inicialmente la disgenesia gonadal fue considerada prácticamente sinónimo de síndrome de Ullrich-Turner, asociado con la ausencia de un cromosoma X (pese a que la primera ilustración de una gónada acintada fue realizada por Bauks en 1805). Actualmente la aplicación sistemática de las distintas técnicas de estudio citogenético permitieron establecer la frecuencia real de esta anomalía tanto en su forma única como cuando se asocia con otras líneas celulares. Pese a que las anomalías estructurales del cromosoma X son menos frecuentes, el análisis de la relación fenotipo cariotipo ha posibilitado establecer la existencia y localización de las determinantes gonadales. La aplicación de las nuevas técnicas de genética molecular permitirá aclarar aún más estos mecanismos. Uno de los más importantes adelantos en el conocimientos etiológico de la disgenesia gonadal fue también la demostración de su asociación con la mutación de un gen único con mecanismo de herencia mendeliana. Esto fue resultado del análisis genealógico en pacientes con disgenesia gonadal cuyo motivo de consulta en muchos casos, era amenorrea secundaria, retardo puberal o irregularidad menstrual junto con otras anomalías fenotípicas comprobándose así la expresividad variable y heterogeneidad genética del cuadro y enfatizando la importancia de ampliar el estudio a nivel familiar. El complemento sexual en estos casos es normal con cariotipo 46,KX o 46,XY,... (AU)

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La disgenesia gonadal producto de una anomalía en la diferenciación de la gónada primitiva puede estar asociada tanto a factores genéticos como ambientales. En los últimos años el aumento en el conocimiento del primero de estos mecanismos etiológicos así como del proceso normal de diferenciación, desarrollo y mantenimiendo de la gónada, junto con una mayor precisión diagnóstica de este cuadro, ha posibilitado establecer el origen del mismo en la mayoría de los casos, permitiendo evaluar el pronóstico y posibles recursos terapéuticos. Inicialmente la disgenesia gonadal fue considerada prácticamente sinónimo de síndrome de Ullrich-Turner, asociado con la ausencia de un cromosoma X (pese a que la primera ilustración de una gónada acintada fue realizada por Bauks en 1805). Actualmente la aplicación sistemática de las distintas técnicas de estudio citogenético permitieron establecer la frecuencia real de esta anomalía tanto en su forma única como cuando se asocia con otras líneas celulares. Pese a que las anomalías estructurales del cromosoma X son menos frecuentes, el análisis de la relación fenotipo cariotipo ha posibilitado establecer la existencia y localización de las determinantes gonadales. La aplicación de las nuevas técnicas de genética molecular permitirá aclarar aún más estos mecanismos. Uno de los más importantes adelantos en el conocimientos etiológico de la disgenesia gonadal fue también la demostración de su asociación con la mutación de un gen único con mecanismo de herencia mendeliana. Esto fue resultado del análisis genealógico en pacientes con disgenesia gonadal cuyo motivo de consulta en muchos casos, era amenorrea secundaria, retardo puberal o irregularidad menstrual junto con otras anomalías fenotípicas comprobándose así la expresividad variable y heterogeneidad genética del cuadro y enfatizando la importancia de ampliar el estudio a nivel familiar. El complemento sexual en estos casos es normal con cariotipo 46,KX o 46,XY,...

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