Lethality of Birth Defects in Live Born Infants Categorized by Gestational Age and Birth Weight.

OBJECTIVE: This study aimed to describe lethality of birth defects (BDs) in newborns categorized by gestational age and birth weight and to identify BDs associated with prematurity. STUDY DESIGN: Live born infants (n = 16,452) with isolated BDs classified by severity, and 42,511 healthy controls were assigned to categories: adequate growth, preterm, or small for gestational age (SGA). Proportion of cases and BDs' lethality rates were obtained by category and compared with controls. RESULTS: Overall fewer malformed than nonmalformed infants were of adequate growth, while the opposite occurred in the preterm and SGA categories where gastroschisis and esophageal atresia were among the most outstanding defects. For most severe BDs, the early neonatal death rate was higher than control values in all categories; for mild defects, except cleft lip in the preterm category, they did not differ. Diaphragmatic hernia showed the highest lethality values, while those of spina bifida were among the lowest. Talipes, hypospadias, and septal heart defects were mild defects significantly associated with prematurity. CONCLUSION: Although reasons, such as induced preterm delivery of fetuses with certain anomalies, could partially account for their high prematurity rates, susceptibility to preterm birth might exist through underlying mechanisms related with the defects. The identification of BDs associated with prematurity should serve to improve measures that prevent preterm birth especially of fetuses at risk. KEY POINTS: · Some BDs predispose to prematurity.. · Prematurity is an additional risk factor for mortality in infants with mild defects.. · Lethality values should be adjusted by gestational age and birth weight..

Preterm birth etiological pathways: a Bayesian networks and mediation analysis approach.

BACKGROUND: The aim of this study was to determine the mediating effect of spontaneous preterm birth (PTB) main predictors that would allow to suggest etiological pathways. METHODS: We carried out a case-control study, including sociodemographic characteristics, habits, health care, and obstetric data of multiparous women who gave birth at a maternity hospital from Tucumán, Argentina, between 2005 and 2010: 998 women without previous PTB who delivered at term and 562 who delivered preterm. We selected factors with the greatest predictive power using a penalized logistic regression model. A data-driven Bayesian network including the selected factors was created where we identified pathways and performed mediation analyses. RESULTS: We identified three PTB pathways whose natural indirect effect was greater than zero with a 95% confidence interval: maternal age less than 20 years mediated by few prenatal visits, vaginal bleeding in the first trimester mediated by vaginal bleeding in the second trimester, and urinary tract infection mediated by vaginal bleeding in the second trimester. The effect mediated in these pathways showed greater sensitivity to confounders affecting the variables mediator-outcome and exposure-mediator in the same direction. CONCLUSION: The identified pathways suggest PTB etiological lines related to social disparities and exposure to genitourinary tract infections. IMPACT: Few prenatal visits (<5) and vaginal bleeding are two of the main predictors for spontaneous preterm birth in the studied population. Few prenatal visits mediates part of the risk associated with maternal age less than 20 years and vaginal bleeding in the second trimester mediates part of the risk associated with vaginal bleeding in the first trimester and with urinary tract infection. Social disparities and exposure to genitourinary tract infections would be etiological lines of spontaneous preterm birth.

Preterm birth and genitourinary tract infections: assessing gene-environment interaction.

BACKGROUND: Preterm birth (PTB) is the leading cause of perinatal morbimortality worldwide. Genetic and environmental factors could raise PTB risk. The aim of this study was to analyze the contribution of the statistical interaction between genes and vaginal-urinary tract infections (VI-UTI) to the risk of PTB by clinical subtype. METHODS: Twenty-four SNPs were genotyped in 18 candidate genes from 352 fetal triads and 106 maternal triads. Statistical interactions were evaluated with conditional logistic regression models based on genotypic transmission/disequilibrium test. RESULTS: In PTB-idiopathic subtype mothers exposed to UTI, fetal SNPs rs11686474 (FSHR), rs4458044 (CRHR1, allele G), rs883319 (KCNN3), and maternal SNP rs1882435 (COL4A3) showed a nominal significant increment in prematurity risk. In preterm premature rupture of membranes (PPROM), fetal SNP rs2277698 (TIMP2) showed a nominal significant risk increment. In mothers exposed to VI, fetal SNP rs5742612 (IGF1) in PTB-PPROM and maternal SNP rs4458044 (CRHR1, allele C) in spontaneous PTB showed nominal significant increment in prematurity risk. CONCLUSIONS: Certain maternal and fetal genes linked to infectious/inflammatory and hormonal regulation processes increase prematurity risk according to clinical subtype when mothers are exposed to UTI or VI. These findings may help in the understanding of PTB etiology and PTB prevention. IMPACT: Preterm birth is a major cause of perinatal morbimortality worldwide and its etiology remains unknown. This work provides evidence on the statistical interaction of six genes with gestational vaginal or urinary infections leading to the occurrence of preterm births. Statistical interactions vary according to infection type, genotype (maternal and fetal), and clinical subtype of prematurity. Certain maternal and fetal genetic variants of genes linked to infectious/inflammatory and hormonal regulation processes would increase the risk of prematurity according to clinical subtype and infection type. Our findings may help in the study of etiology of preterm birth and its prevention.

Individual deprivation, regional deprivation, and risk for oral clefts in Argentina.

OBJECTIVE: The aim of this study was to analyze the effects of individual low socioeconomic status (SES) and deprived geographical area (GA) on the occurrence of isolated cleft lip with or without cleft palate (CL±P) in Argentina. METHODS: This case-control study included 577 newborns with isolated CL±P and 13 344 healthy controls, born between 1992 and 2001, from a total population of 546 129 births in 39 hospitals in Argentina. Census data on unsatisfied basic needs were used to establish the degree of geographical area deprivation. An SES index for each individual was established, using maternal age, gravidity, low paternal and maternal education, and low-level paternal occupation. Logistic regression was used to assess the effects of low SES and of deprived GA on CL±P. RESULTS: A slightly increased risk of CL±P was observed in mothers with a low SES, while a deprived GA showed no effect. Native ancestry, acute maternal illnesses, and poor prenatal care were significant risk factors for CL±P for the mothers with low SES, after using propensity scores to adjust for the demographic characteristics in cases and controls. CONCLUSIONS: Low individual SES slightly increased the risk for CL±P, but a deprived GA did not have that effect. There was no interaction between individual SES and deprived GA. Factors related to low individual SES-including poor prenatal care, low parental education, lack of information, and lifestyle factors-should be primarily targeted as risk factors for CL±P rather than factors related to a deprived place of residence.

Association of candidate gene polymorphisms with clinical subtypes of preterm birth in a Latin American population.

BackgroundPreterm birth (PTB) is the leading cause of neonatal mortality and morbidity. PTB is often classified according to clinical presentation as follows: idiopathic (PTB-I), preterm premature rupture of membranes (PTB-PPROM), and medically induced (PTB-M). The aim of this study was to evaluate the associations between specific candidate genes and clinical subtypes of PTB.MethodsTwenty-four single-nucleotide polymorphisms (SNPs) were genotyped in 18 candidate genes in 709 infant triads. Of them, 243 were PTB-I, 256 were PTB-PPROM, and 210 were PTB-M. These data were analyzed with a Family-Based Association.ResultsPTB was nominally associated with rs2272365 in PON1, rs883319 in KCNN3, rs4458044 in CRHR1, and rs610277 in F3. Regarding clinical subtypes analysis, three SNPs were associated with PTB-I (rs2272365 in PON1, rs10178458 in COL4A3, and rs4458044 in CRHR1), rs610277 in F3 was associated with PTB-PPROM, and rs883319 in KCNN3 and rs610277 in F3 were associated with PTB-M.ConclusionOur study identified polymorphisms potentially associated with specific clinical subtypes of PTB in this Latin American population. These results could suggest a specific role of such genes in the mechanisms involved in each clinical subtype. Further studies are required to confirm our results and to determine the role of these genes in the pathophysiology of clinical subtypes.

Descriptive analysis of high birth prevalence rate geographical clusters of congenital anomalies in South America.

BACKGROUND: The birth prevalence rate (BPR) of congenital anomalies (CAs) is heterogeneous and exhibits geographical and sociocultural variations throughout the world. In South America (SA), high birth prevalence regions of congenital anomalies have been observed. The aim of this study was to identify, describe, and characterize geographical clusters of congenital anomalies in SA. METHODS: This observational descriptive study is based on clinical epidemiological data registered by the Latin-American Collaborative Study of Congenital Malformations network. Between 1995 and 2012, a total of 25,082 malformed newborns were ascertained from 2,557,424 births at 129 hospitals in SA. The spatial scan statistic was used to determine geographical regions with high BPR of CAs. The BPR was obtained with a Poisson regression model. Odds ratios were estimated for several risk factors inside the geographical clusters. RESULTS: We confirmed the existence of high BPR regions of CAs in SA. Indicators of low socioeconomic conditions, such as a low maternal education, extreme age childbearing, infectious diseases, and medicine use during pregnancy were detected as risk factors inside these regions. Native and African ancestries with high frequency of consanguineous marriages could explain partially these high BPR clusters. CONCLUSION: The recognition of clusters could be a starting point in the identification of susceptibility genes associated with the occurrence of CA in high BPR regions.

Gastroschisis and young mothers: What makes them different from other mothers of the same age?

BACKGROUND: Although young maternal age has been identified as a risk factor for gastroschisis, its role remains undisclosed. To our knowledge, the differences between young mothers of infants with gastroschisis and young mothers of infants with other pregnancy outcomes have not been established. The aim of this work was to compare characteristics of young mothers whose newborn had gastroschisis with same aged mothers of malformed and nonmalformed control infants, diagnosed within the ECLAMC maternity hospital network. METHODS: Data base records of live and stillborn infants of one of three groups (with isolated gastroschisis, with 1 of 5 other isolated birth defects, and nonmalformed), and whose mothers were younger than 20 years, were selected. Secular trends were obtained for all birth defects; frequencies and odds ratios (OR) of demographic and reproductive variables were compared among the 3 groups. Significantly associated variables were adjusted with a multivariate regression. RESULTS: The association was higher with gastroschisis 1) than with other birth defects for African ancestry, smoking, adequate prenatal control and diagnosis 2) than with nonmalformed controls for maternal illnesses and alcohol 3) and than both for previous pregnancy loss and medication, mainly sex hormones. After adjustment, only previous pregnancy loss maintained its significance when compared with malformed (OR = 2.34; 1.37-3.97; P = 0.002), as well as with nonmalformed (OR = 3.43; 2.07-5.66; P < 0.001) controls. CONCLUSION: A previous pregnancy loss was identified as the main risk factor for gastroschisis, while an increased use of sex hormones, perhaps related to the previous loss, could trigger a disruptive mechanism, due to their thrombophilic effect.

Minor anomalies: can they predict specific major defects? A study based on 23 major and 14 minor anomalies in over 25,000 newborns with birth defects.

BACKGROUND: Minor anomalies (mAs) are morphological features with little clinical relevance that have been mentioned as possible predictors of major defects (MDs). OBJECTIVES: To identify the preferential associations between selected MDs and mAs and to establish if mAs can serve as predictors for specific MDs. STUDY DESIGN: Information of newborns with birth defects was obtained from the ECLAMC (Latin American Collaborative Study of Congenital Malformations) database. The sample consisted of 27,247 live- and stillborn newborns with multiple malformations that included at least one of the selected MDs or mAs. The odds ratio and predictive values were calculated for significant associations, and concurrence rates in first degree relatives. RESULTS: A total of 33 significant minor-major associations were identified. Single umbilical artery (SUA) and preauricular tags were the most frequent mAs; the former was associated with 10 MDs, the latter only with microtia. The highest positive predictive value was shown by SUA for anal atresia. Newborns with preauricular tags had significantly more relatives with microtia than expected. CONCLUSIONS: No new relevant associations between MDs and mAs were identified and few mAs seem to serve as predictors for specific MDs in the same newborn. However, preauricular tags can predict the occurrence of microtia in other family members.

Is gravidity 4+ a risk factor for oral clefts? A case-control study in eight South american countries using structural equation modeling.

Background : There is disagreement about the association between cleft lip with or without cleft palate and multigravidity, which could be explained by differences of adjusting for maternal age, Amerindian ancestry, and socioeconomic status. Objective : The aim was to evaluate gravidity 4+ (four or more gestations) as a risk factor for cleft lip with or without cleft palate in South America. Design : We used a matched (1:1) case-control study with structural equation modeling for related causes. Data were obtained from 1,371,575 consecutive newborn infants weighing ≥500 g who were born in the hospitals of the Estudio Colaborativo Latinoamericano de Malformaciones Congénitas (ECLAMC) network between 1982 and 1999. There were a total of 1,271 cases with cleft lip with or without cleft palate (excluding midline and atypical cleft lip with or without cleft palate). A total of 1,227 case-control pairs were obtained, matched by maternal age, newborn gender, and year and place of birth. Potential confounders and intermediary variables were analyzed with structural equation modeling. Results : The crude risk of gravidity 4+ was 1.41 and the 95% confidence interval was 1.14 to 1.61. When applying structural equation modeling, the effect of multigravidity on the risk of cleft lip with or without cleft palate was 1.22 and the 95% confidence interval was 0.91 to 1.39. Conclusions : Multigravid mothers (more than four gestations) showed no greater risk of bearing children who had cleft lip with or without cleft palate than mothers with two or three births. Therefore, the often observed and reported association between multigravidity and oral clefts likely reflects the effect of other risk factors related to low socioeconomic status in South American populations.

[Social inequities in teenage mothers and the relationship to adverse perinatal outcomes in South American populations]. / Inequidades sociales en madres adolescentes y la relación con resultados perinatales adversos en poblaciones sudamericanas.

The aim was to explain differences in the rates of adverse perinatal events in teenage mothers with low and high schooling. The sample was collected from the Latin American Colaborative Study of Congenital Malformations (ECLAMC) database. From a total of 2,443,747 births in 93 hospitals, 66,755 live newborns without congenital malformations were recruited from 2000 to 2017. Teenage mothers were classified according to low, medium, and high schooling. A multivariate model was used that included reproductive history, access to health services, demographic and socioeconomic variables, and ethnic group. The Fairlie decomposition model was applied to quantify the contribution of explanatory variables to the adverse perinatal event rates. Of the 66,755 newborns analyzed, 21.1% (n = 14,078) were born to teenage mothers. Distribution of maternal schooling was 24.2%, 59.8%, and 16% for low, medium, and high schooling, respectively. The highest rates of adverse perinatal events were seen in teenage mothers with low schooling. The variable "access to health services" explained 35%, 37%, and 23% of the disparities in low birthweight, prematurity, and intrauterine growth restriction, respectively, among teenage mother with low and high schooling. Low number of prenatal visits was the only risk factor for the two levels of schooling and the variable that best explained the differences between the rates of adverse perinatal events. From the public health perspective, prenatal care represents a low-cost intervention with the possibility of increased implementation through adequate information for the population and systematic measures in primary care.

El objetivo fue explicar las diferencias en la frecuencia de eventos perinatales adversos entre madres adolescentes con baja y alta escolaridad. La muestra poblacional se recogió en la base de datos del Estudio Colaborativo Latinoamericano de Malformaciones Congénitas (ECLAMC). Entre 2.443.747 nacimientos ocurridos en 93 hospitales, se reclutaron 66.755 recién nacidos vivos, sin defectos congénitos, durante el período 2000-2017. Las madres adolescentes se clasificaron según su escolaridad en: baja, media y alta. Se utilizó un modelo multivariado, que incluyó efectos reproductivos, acceso a servicios de salud, variables demográficas-socioeconómicas, así como de grupo étnico. El modelo de descomposición de Fairlie se aplicó para cuantificar la contribución de variables explicativas en las frecuencias de eventos perinatales adversos. De los 66.755 recién nacidos investigados, el 21,1% (n = 14.078) fue primigrávida de madres adolescentes. La distribución por escolaridad materna fue de 24,2%, 59,8% y 16% para baja, media y alta escolaridad, respectivamente. Las mayores frecuencias de eventos perinatales adversos se observaron en madres adolescentes con baja escolaridad. La variable "acceso a servicios de salud" explicó un 35%, 37% y 23% de las disparidades en el bajo peso al nacimiento, prematuridad y retardo de crecimiento intrauterino, respectivamente, entre madres adolescentes con baja y alta escolaridad. El bajo número de consultas prenatales fue el único factor de riesgo para los dos niveles de escolaridad y la variable que mejor explica las diferencias entre las frecuencias de eventos perinatales adversos. Desde el punto de vista de la salud pública, ellos representan una intervención de bajo coste, con posibilidad de que se incrementen mediante información adecuada para la población y medidas sistemáticas en los niveles de atención primaria.

O objetivo foi explicar as diferenças na frequência de eventos perinatais adversos entre mães adolescentes com baixa e alta escolaridade. A amostra populacional foi coletada na base de dados do Estudo Colaborativo Latino-Americano de Malformações Congênitas (ECLAMC). Entre 2.443.747 nascimentos ocorridos em 93 hospitais, 66.755 recém-nascidos vivos sem defeitos congênitos foram recrutados no período 2000-2017. As mães adolescentes foram classificadas segundo sua escolaridade em: baixa, média e alta. Foi utilizado um modelo multivariado que incluiu efeitos reprodutivos, acesso a serviços de saúde, variáveis demográficas-socioeconômicas e de grupo étnico. O modelo de decomposição de Fairlie foi aplicado para quantificar a contribuição de variáveis explicativas nas frequências de eventos perinatais adversos. Dos 66.755 recém-nascidos pesquisados, o 21,1% (n = 14.078) foi a mãe adolescente. A distribuição por escolaridade materna foi de 24,2%, 59,8% e 16% para baixa escolaridade, média escolaridade e alta escolaridade, respectivamente. As maiores frequências de eventos perinatais adversos foram observadas em mães adolescentes com baixa escolaridade. A variável "acesso a serviços de saúde"; explicou 35%, 37% e 23% das disparidades no baixo peso ao nascer, prematuridade e retardo de crescimento intrauterino, respectivamente, entre mães adolescentes com baixa e alta escolaridades. O baixo número de consultas pré-natais foi o único fator de risco para os dois níveis de escolaridade e a variável que melhor explica as diferenças entre as frequências de eventos perinatais adversos. Do ponto de vista da saúde pública, eles representam uma intervenção de baixo custo, com possibilidade de ser incrementadas por meio de informações adequadas à população e medidas sistemáticas nos níveis de atenção primária.

A graph theory approach to analyze birth defect associations.

Birth defects are prenatal morphological or functional anomalies. Associations among them are studied to identify their etiopathogenesis. The graph theory methods allow analyzing relationships among a complete set of anomalies. A graph consists of nodes which represent the entities (birth defects in the present work), and edges that join nodes indicating the relationships among them. The aim of the present study was to validate the graph theory methods to study birth defect associations. All birth defects monitoring records from the Estudio Colaborativo Latino Americano de Malformaciones Congénitas gathered between 1967 and 2017 were used. From around 5 million live and stillborn infants, 170,430 had one or more birth defects. Volume-adjusted Chi-Square was used to determine the association strength between two birth defects and to weight the graph edges. The complete birth defect graph showed a Log-Normal degree distribution and its characteristics differed from random, scale-free and small-world graphs. The graph comprised 118 nodes and 550 edges. Birth defects with the highest centrality values were nonspecific codes such as Other upper limb anomalies. After partition, the graph yielded 12 groups; most of them were recognizable and included conditions such as VATER and OEIS associations, and Patau syndrome. Our findings validate the graph theory methods to study birth defect associations. This method may contribute to identify underlying etiopathogeneses as well as to improve coding systems.

Limb body wall complex: Its delineation and relationship with amniotic bands using clustering methods.

BACKGROUND: Despite the numerous reports on the limb body wall complex (LBWC), this association has never been adequately defined. Amniotic bands (AB) are frequently present but their role remains unclear. Since most reports were based on clinical and often subjective diagnoses, the aim of this work was to define LBWC and the role of AB, minimizing subjectivity. METHODS: Data were obtained from the ECLAMC maternity hospitals network database. A total of 450 live and stillborn infants, born during 1967-2013, with AB or the LBWC were selected. A hierarchical cluster analysis was used to classify cases into homogeneous groups (sharing similar associated defects); robustness of the classification was confirmed with a discriminant analysis. The frequency of associated defects was compared among groups; those whose frequency differed significantly were included in a logistic regression to establish their association within each group. RESULTS: The cluster analysis identified two groups: a body wall defect (BWD) predominating in one, AB in the other. These groups were further divided into: BWD (cases with only BWD), AB (with only AB), BWD + AB, and NONE (with neither). Association with caudal defects and lower limb amelia was observed for BWD, with cephalic defects and upper limb amputations for BWD + AB. CONCLUSIONS: The results, obtained with the least possible subjectivity, indicated that BWD and BWD + AB are different conditions. Since BWD specifically associates with amelia, we propose that this defect and not any limb deficiency should be considered as inclusion criterium and that it should be included in the BWD acronym as LBWC.

Explaining ethnic disparities in preterm birth in Argentina and Ecuador.

Little is understood about racial/ethnic disparities in infant health in South America. We quantified the extent to which the disparity in preterm birth (PTB; <37 gestational weeks) rate between infants of Native only ancestry and those of European only ancestry in Argentina and Ecuador are explained by household socio-economic, demographic, healthcare use, and geographic location indicators. The samples included 5199 infants born between 2000 and 2011 from Argentina and 1579 infants born between 2001 and 2011 from Ecuador. An Oaxaca-Blinder type decomposition model adapted to binary outcomes was estimated to explain the disparity in PTB risk across groups of variables and specific variables. Maternal use of prenatal care services significantly explained the PTB disparity, by nearly 57% and 30% in Argentina and Ecuador, respectively. Household socio-economic status explained an additional 26% of the PTB disparity in Argentina. Differences in maternal use of prenatal care may partly explain ethnic disparities in PTB in Argentina and Ecuador. Improving access to prenatal care may reduce ethnic disparities in PTB risk in these countries.

Prevalence of low birth weight in a scenario of economic depression in Argentina. / Prevalencia del bajo peso al nacer en un escenario de depresión económica en Argentina.

INTRODUCTION: Low birth weight (LBW) is considered a general indicator of health because it is related to complications in the life of a newborn infant and is one of the leading causes of infant mortality. It is a multifactorial indicator, and its determinants include socioeconomic factors. OBJECTIVE: To assess the impact of economic inequality on the prevalence of LBW by quantifying its differential effect by maternal age, level of maternal education, and level of care. POPULATION AND METHODS: Epidemiological, cross-sectional study that analyzed all births occurred in Argentina between 2001 and 2013 based on data provided by the National Registry of births, corresponding to the Health Statistics and Information Department. The temporal variation in the prevalence of LBW newborn infants (< 2500 grams) and its relation to demographic and socioeconomic indicators were studied. Its association was assessed using logistic regression models. RESULTS: A total of 9 001 960births were included. The prevalence of LBW newborn infants during the 2001 economic crisis increased -6% in 2002 and 7% in 2003- The impact was heterogeneous and higher on public hospitals (|-1;PR|-3; = 1.03) and adolescent mothers (PR=1.07), but no impact was observed on a low level of maternal education (PR= 0.99). CONCLUSIONS: The impact of socioeconomic inequality on the prevalence of LBW was significant and heterogeneous, especially on public hospitals and mothers at the extremes of maternal age.

Introducción. El bajo peso al nacer (BPN) es considerado un indicador general de salud por su relación con complicaciones en la vida del recién nacido y por ser una de las primeras causas de mortalidad infantil. Es multifactorial y, entre sus determinantes, se incluyen los socioeconómicos. Objetivo. Evaluar el impacto de la desigualdad económica sobre la prevalencia del BPN, cuantificando el efecto diferencial según edad y educación materna y nivel de atención. Población y métodos. Estudio epidemiológico de diseño transversal, en el cual se analizaron los nacimientos ocurridos en Argentina desde 2001 a 2013 con datos obtenidos del Registro Nacional de los nacimientos, perteneciente a la Dirección de Estadísticas e Información en Salud (DEIS). Se estudió la variación temporal de la prevalencia de recién nacidos con BPN (< 2500 gramos) y su relación con indicadores demográficos y socioeconómicos. Se evaluó su asociación a través de modelos de regresión logística. Resultados. Se incluyeron 9 001 960 nacimientos. Se observó un incremento en la prevalencia de recién nacidos con BPN durante la crisis económica de 2001 -de un 6% en 2002 y un 7% en 2003-. Fue heterogéneo y tuvo mayor impacto en hospitales públicos (razón de prevalencia -RP-= 1,03) y madres adolescentes (RP= 1,07) y ningún impacto sobre la educación materna baja (RP= 0,99). Conclusiones. El impacto de la desigualdad socioeconómica sobre la prevalencia de bajo peso fue significativo y heterogéneo, más importante en hospitales públicos y madres en edades extremas.

Neural tube defects: Sex ratio changes after fortification with folic acid.

BACKGROUND: Historically, neural tube defects (NTDs) have predominated in female infants but the reasons remain unclear. In South America, the pre- folic acid fortification (FAF) rates of NTDs were around 18/10,000 births for females and 12/10,000 births for males, with an estimated sex ratio (male/female) of 0.67. During the post- FAF period, unpublished routine reports have indicated changes in the sex ratio for these defects while some descriptive reports are controversial. To date and to our knowledge, however, no studies specifically focusing on these changes to test this hypothesis directly have been undertaken. The aim of this study was to analyze changes in the sex ratio of infants with NTDs after FAF in South American countries. MATERIALS AND METHODS: With a descriptive cross-sectional study design, 2,597 infants with isolated NTDs born between 1990 and 2013 in 3 countries participating in the Latin American Collaborative Study of Congenital Malformations (ECLAMC) network were included: (Chile N = 521 and Argentina N = 1,619 [with FAF policies]; Venezuela N = 457 [without FAF policies; used as control]; total births = 2,229,561). The differences-in-differences method and Poisson regressions were used to evaluate the sex ratio shift from female to male before vs. after FAF, and to assess whether these differences were related to the fortification. RESULTS AND CONCLUSIONS: In Chile and Argentina the prevalence of NTDs, particularly anencephaly and cervico-thoracic spina bifida, showed a greater reduction rate in females than in males after FAF, resulting in a change of the sex ratio of infants with NTDs. Some mechanisms possibly involved in this differential reduction are proposed which might be useful to identify the pathogenesis of NTDs as a whole and specifically of those susceptible to the protective effect of folic acid.

Association between a Maternal History of Miscarriages and Birth Defects.

BACKGROUND: Some studies, mainly in the older literature, observed a significant association between miscarriages and birth defects (BDs) occurring in the same sibship. However, few studies examined the BD/miscarriage relationship in depth. In addition nothing has been added to the underlying mechanisms possibly linking both events. The purpose of this work was to identify specific BDs associated with maternal miscarriages. In particular, it examined whether the risk depended on the number of losses, and to suggest the existence of specific factors for each BD/miscarriage association observed. METHODS: The study relied on the Latin American Collaborative Study on Congenital Malformations (ECLAMC) database registries including 26,906 live and stillborn infants with one of 19 selected isolated BDs and 93,853 normal controls. Infants born to primigravid mothers were excluded from the present study. Demographic and reproductive variables were compared between control mothers With and Without previous miscarriages. The number, frequency, and distribution of miscarriages were observed for each BD and controls. A conditional logistic regression was applied to evaluate the miscarriage risk for each BD. RESULTS: Control mothers with previous miscarriages were older, had had more pregnancies, and were less educated. Three risk patterns of miscarriages were observed: a very high risk of miscarriages associated with gastroschisis, omphalocele, and talipes; only one miscarriage associated with spina bifida, and two or more miscarriages associated with hypospadias. CONCLUSION: These three patterns suggest that different factors underly each BD/miscarriage association: infertility for hypospadias, vascular disruption for gastroschisis and talipes, while for spina bifida, the much debated trophoblastic cell residue theory could not be discarded. Birth Defects Research 109:254-261, 2017. © 2017 Wiley Periodicals, Inc.

Maternal and neonatal epidemiological features in clinical subtypes of preterm birth.

OBJECTIVE: This study was designed to characterize and compare the maternal and newborn epidemiological characteristics through analysis of environmental factors, sociodemographic characteristics and clinical characteristics between the different clinical subtypes of preterm birth (PTB): Idiopathic (PTB-I), premature rupture of the membranes (PTB-PPROM) and medically indicated (PTB-M). The two subtypes PTB-I and PTB-PPROM grouped are called spontaneous preterm births (PTB-S). METHODS: A retrospective, observational study was conducted in 1.291 preterm nonmalformed singleton live-born children to nulliparous and multiparous mother's in Tucumán-Argentina between 2005 and 2010. Over 50 maternal variables and 10 newborn variables were compared between the different clinical subtypes. The comparisons were done to identify heterogeneity between subtypes of preterm birth: (PTB-S) versus (PTB-M), and within spontaneous subtype: (PTB-I) versus (PTB-PPROM). In the same way, two conditional logistic multivariate regressions were used to compare the odds ratio (OR) between PTB-S and PTB-M, as well as PTB-I and PTB-PPROM. We matched for maternal age when comparing maternal variables and gestational age when comparing infant variables. RESULTS: The PTB-I subtype was characterized by younger mothers of lower socio-economic status, PTB-PPROM was characterized by environmental factors resulting from inflammatory processes, and PTB-M was characterized by increased maternal or fetal risk pregnancies. CONCLUSIONS: The main risk factor for PTB-I and PTB-M was having had a prior preterm delivery; however, previous spontaneous abortion was not a risk factor, suggesting a reproductive selection mechanism.

Disparities in birth weight and gestational age by ethnic ancestry in South American countries.

OBJECTIVES: We examine disparities in birth weight and gestational age by ethnic ancestry in 2000-2011 in eight South American countries. METHODS: The sample included 60,480 singleton live births. Regression models were estimated to evaluate differences in birth outcomes by ethnic ancestry controlling for time trends. RESULTS: Significant disparities were found in seven countries. In four countries-Brazil, Ecuador, Uruguay, and Venezuela-we found significant disparities in both low birth weight and preterm birth. Disparities in preterm birth alone were observed in Argentina, Bolivia, and Colombia. Several differences in continuous birth weight, gestational age, and fetal growth rate were also observed. There were no systematic patterns of disparities between the evaluated ethnic ancestry groups across the study countries, in that no racial/ethnic group consistently had the best or worst outcomes in all countries. CONCLUSIONS: Racial/ethnic disparities in infant health are common in several South American countries. Differences across countries suggest that racial/ethnic disparities are driven by social and economic mechanisms. Researchers and policymakers should acknowledge these disparities and develop research and policy programs to effectively target them.

Inequidades sociales en madres adolescentes y la relación con resultados perinatales adversos en poblaciones sudamericanas / Social inequities in teenage mothers and the relationship to adverse perinatal outcomes in South American populations / Iniquidades sociais em mães adolescentes e sua relação com resultados perinatais adversos em populações sul-americanas

Resumen: El objetivo fue explicar las diferencias en la frecuencia de eventos perinatales adversos entre madres adolescentes con baja y alta escolaridad. La muestra poblacional se recogió en la base de datos del Estudio Colaborativo Latinoamericano de Malformaciones Congénitas (ECLAMC). Entre 2.443.747 nacimientos ocurridos en 93 hospitales, se reclutaron 66.755 recién nacidos vivos, sin defectos congénitos, durante el período 2000-2017. Las madres adolescentes se clasificaron según su escolaridad en: baja, media y alta. Se utilizó un modelo multivariado, que incluyó efectos reproductivos, acceso a servicios de salud, variables demográficas-socioeconómicas, así como de grupo étnico. El modelo de descomposición de Fairlie se aplicó para cuantificar la contribución de variables explicativas en las frecuencias de eventos perinatales adversos. De los 66.755 recién nacidos investigados, el 21,1% (n = 14.078) fue primigrávida de madres adolescentes. La distribución por escolaridad materna fue de 24,2%, 59,8% y 16% para baja, media y alta escolaridad, respectivamente. Las mayores frecuencias de eventos perinatales adversos se observaron en madres adolescentes con baja escolaridad. La variable "acceso a servicios de salud" explicó un 35%, 37% y 23% de las disparidades en el bajo peso al nacimiento, prematuridad y retardo de crecimiento intrauterino, respectivamente, entre madres adolescentes con baja y alta escolaridad. El bajo número de consultas prenatales fue el único factor de riesgo para los dos niveles de escolaridad y la variable que mejor explica las diferencias entre las frecuencias de eventos perinatales adversos. Desde el punto de vista de la salud pública, ellos representan una intervención de bajo coste, con posibilidad de que se incrementen mediante información adecuada para la población y medidas sistemáticas en los niveles de atención primaria.

Abstract: The aim was to explain differences in the rates of adverse perinatal events in teenage mothers with low and high schooling. The sample was collected from the Latin American Colaborative Study of Congenital Malformations (ECLAMC) database. From a total of 2,443,747 births in 93 hospitals, 66,755 live newborns without congenital malformations were recruited from 2000 to 2017. Teenage mothers were classified according to low, medium, and high schooling. A multivariate model was used that included reproductive history, access to health services, demographic and socioeconomic variables, and ethnic group. The Fairlie decomposition model was applied to quantify the contribution of explanatory variables to the adverse perinatal event rates. Of the 66,755 newborns analyzed, 21.1% (n = 14,078) were born to teenage mothers. Distribution of maternal schooling was 24.2%, 59.8%, and 16% for low, medium, and high schooling, respectively. The highest rates of adverse perinatal events were seen in teenage mothers with low schooling. The variable "access to health services" explained 35%, 37%, and 23% of the disparities in low birthweight, prematurity, and intrauterine growth restriction, respectively, among teenage mother with low and high schooling. Low number of prenatal visits was the only risk factor for the two levels of schooling and the variable that best explained the differences between the rates of adverse perinatal events. From the public health perspective, prenatal care represents a low-cost intervention with the possibility of increased implementation through adequate information for the population and systematic measures in primary care.

Resumo: O objetivo foi explicar as diferenças na frequência de eventos perinatais adversos entre mães adolescentes com baixa e alta escolaridade. A amostra populacional foi coletada na base de dados do Estudo Colaborativo Latino-Americano de Malformações Congênitas (ECLAMC). Entre 2.443.747 nascimentos ocorridos em 93 hospitais, 66.755 recém-nascidos vivos sem defeitos congênitos foram recrutados no período 2000-2017. As mães adolescentes foram classificadas segundo sua escolaridade em: baixa, média e alta. Foi utilizado um modelo multivariado que incluiu efeitos reprodutivos, acesso a serviços de saúde, variáveis demográficas-socioeconômicas e de grupo étnico. O modelo de decomposição de Fairlie foi aplicado para quantificar a contribuição de variáveis explicativas nas frequências de eventos perinatais adversos. Dos 66.755 recém-nascidos pesquisados, o 21,1% (n = 14.078) foi a mãe adolescente. A distribuição por escolaridade materna foi de 24,2%, 59,8% e 16% para baixa escolaridade, média escolaridade e alta escolaridade, respectivamente. As maiores frequências de eventos perinatais adversos foram observadas em mães adolescentes com baixa escolaridade. A variável "acesso a serviços de saúde"; explicou 35%, 37% e 23% das disparidades no baixo peso ao nascer, prematuridade e retardo de crescimento intrauterino, respectivamente, entre mães adolescentes com baixa e alta escolaridades. O baixo número de consultas pré-natais foi o único fator de risco para os dois níveis de escolaridade e a variável que melhor explica as diferenças entre as frequências de eventos perinatais adversos. Do ponto de vista da saúde pública, eles representam uma intervenção de baixo custo, com possibilidade de ser incrementadas por meio de informações adequadas à população e medidas sistemáticas nos níveis de atenção primária.