Genetic susceptibility for retinopathy of prematurity and its associated comorbidities.

BACKGROUND: Retinopathy of prematurity (ROP) is one of the leading cause of child blindness. Preterm newborns of very low gestational age (GA) and very low birth weight are at the greatest risk. Our objective was to evaluate the role of genetic variants associated with ROP risk and its comorbidities in an Argentinian sample of premature infants. METHODS: A sample of 437 preterm infants <33 weeks GA, born at a maternity hospital in Tucumán, Argentina, 2005-2010, was analyzed. Environmental factors, perinatal outcomes, and fourteen single nucleotide polymorphisms associated with ROP were evaluated, comparing ROP with non-ROP newborns. A lasso logistic regression was performed to select variables; then, a conditional logistic regression was used to identify ROP maternal and perinatal risk factors adjusting by maternal and gestational ages, respectively. RESULTS: ROP maternal risk factors were alcohol intake, periodontal infections, and severe stress. Respiratory distress, sepsis, and intracranial hemorrhage were the ROP perinatal risk factors. Markers rs186085 of EPAS1 and rs427832 of AGTR1 were significantly associated with ROP newborns. CONCLUSION: We identified three maternal and three perinatal risk factors associated with ROP. Genes EPAS1 and AGTR1, involved in angiogenesis and vascularization, were identified to be of risk for ROP. IMPACT: Genetic and environmental risk factors associated with ROP and its comorbidities are evaluated in a Latin American population. Genes EPAS1 and AGTR1, involved in angiogenesis and vascularization, were identified to be of risk for ROP. Three maternal and three perinatal risk factors associated with ROP were also identified. A matrix of significant relationships among genetic markers and comorbidities is presented. Reported data may help develop more effective preventive measures for ROP in the Latin American region.

Gene-environment interactions and preterm birth predictors: A Bayesian network approach.

Preterm birth (PTB) is the main condition related to perinatal morbimortality worldwide. The aim of this study was to identify gene-environment interactions associated with spontaneous PTB or its predictors. We carried out a retrospective case-control study including parental sociodemographic and obstetric data as well as newborn genetic variants of 69 preterm and 61 at term newborns born at a maternity hospital from Tucumán, Argentina, between 2005 and 2010. A data-driven Bayesian network including the main PTB predictors was created where we identified gene-environment interactions. We used logistic regressions to calculate the odds ratios and confidence intervals of the interactions. From the main PTB predictors (nine exposures and six genetic variants) we identified an interaction between low neighbourhood socioeconomic status and rs2074351 (PON1, genotype GG) variant that was associated with an increased risk of toxoplasmosis (odds ratio 12.51, confidence interval 95%: 1.71 - 91.36). The results of this exploratory study suggest that structural social disparities could influence the PTB risk by increasing the frequency of exposures that potentiate the risk associated with individual characteristics such as genetic traits. Future studies with larger sample sizes are necessary to confirm these findings.

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.

Genetic Imbalances in Argentinean Patients with Congenital Conotruncal Heart Defects.

Congenital conotruncal heart defects (CCHD) are a subset of serious congenital heart defects (CHD) of the cardiac outflow tracts or great arteries. Its frequency is estimated in 1/1000 live births, accounting for approximately 10⁻30% of all CHD cases. Chromosomal abnormalities and copy number variants (CNVs) contribute to the disease risk in patients with syndromic and/or non-syndromic forms. Although largely studied in several populations, their frequencies are barely reported for Latin American countries. The aim of this study was to analyze chromosomal abnormalities, 22q11 deletions, and other genomic imbalances in a group of Argentinean patients with CCHD of unknown etiology. A cohort of 219 patients with isolated CCHD or associated with other major anomalies were referred from different provinces of Argentina. Cytogenetic studies, Multiplex-Ligation-Probe-Amplification (MLPA) and fluorescent in situ hybridization (FISH) analysis were performed. No cytogenetic abnormalities were found. 22q11 deletion was found in 23.5% of the patients from our cohort, 66% only had CHD with no other major anomalies. None of the patients with transposition of the great vessels (TGV) carried the 22q11 deletion. Other 4 clinically relevant CNVs were also observed: a distal low copy repeat (LCR)D-E 22q11 duplication, and 17p13.3, 4q35 and TBX1 deletions. In summary, 25.8% of CCHD patients presented imbalances associated with the disease.

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.

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.

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.

Objetivo. Analizar los efectos de un bajo nivel socioeconómico individual y una zona geográfica desfavorable en la aparición del labio leporino aislado con o sin paladar hendido (LL ± P) en Argentina. Métodos. En este estudio de casos y controles se incluyeron 577 recién nacidos con LL ± P aislado y 13 344 controles sanos nacidos entre 1992 y 2001, de un total de 546 129 nacimientos ocurridos en 39 hospitales de Argentina. Para identificar las zonas geográficas desfavorables se utilizaron datos del Índice de Necesidades Básicas Insatisfechas. Se calculó un índice de nivel socioeconómico para cada participante usando la edad materna, el número de embarazos, el nivel de instrucción bajo del padre y la madre, y el nivel de ocupación bajo del padre. Se usó regresión logística para evaluar los efectos de un bajo nivel socioeconómico y una zona geográfica desfavorable en la ocurrencia de LL ± P. Resultados. Se observó un riesgo levemente mayor de LL ± P en madres con bajo nivel socioeconómico, mientras que una zona geográfica desfavorable no mostró ningún efecto. La ascendencia indígena, las enfermedades agudas maternas y una atención prenatal deficiente fueron factores de riesgo significativos para LL ± P en madres con bajo nivel socioeconómico, después de ajustar las características demográficas de casos y controles mediante análisis de propensión. Conclusiones. Un bajo nivel socioeconómico aumentó levemente el riesgo de LL ± P, pero una zona geográfica desfavorable no mostró ese efecto. No hubo interacción entre un bajo nivel socioeconómico individual y una zona geográfica desfavorable. Los factores relacionados con un bajo nivel socioeconómico individual —inclusive una atención prenatal deficiente, la baja educación de los padres, la falta de información y el estilo de vida— deben abordarse principalmente como factores de riesgo de LL ± P más que los factores relacionados con una zona de residencia desfavorable.

Objetivo. Examinar os efeitos do baixo nível socioeconômico individual e área geográfica em situação de carência na ocorrência de fissura labial isolada com ou sem fissura palatina (FL ± P) na Argentina. Métodos. Estudo de caso-controle que compreendeu 577 recém-nascidos com FL isolada ± P e 13 344 controles saudáveis, nascidos entre 1992 e 2001, de uma população total de 546 129 nascimentos em 39 hospitais na Argentina. Foram usados dados censitários sobre necessidades básicas existentes para estabelecer o grau de carência das áreas geográficas. Foi determinado um índice de nível socioeconômico para cada indivíduo baseado na idade materna, número de gestações, baixa escolaridade materna e paterna e ocupação paterna de baixo nível. Foi realizada uma regressão logística para avaliar os efeitos do baixo nível socioeconômico e área geográfica em situação de carência na ocorrência de FL ± P. Resultados. Observou-se um risco discretamente aumentado de FL ± P em mães com baixo nível socioeconômico, mas nenhum efeito foi verificado quanto à área geográfica em situação de carência. Descendência indígena, doença materna aguda e assistência pré-natal precária foram fatores de risco importantes para FL ± P nas mães com baixo nível socioeconômico, após o uso de escores de propensão para ajustar as características demográficas em casos e controles. Conclusões. O baixo nível socioeconômico individual foi associado a um discreto aumento do risco de FL ± P, mas este efeito não foi observado para área geográfica em situação de carência. Não houve interação entre nível socioeconômico individual e área geográfica em situação de carência. Fatores relacionados ao baixo nível socioeconômico individual, como assistência pré-natal precária, baixa escolaridade dos pais, falta de informação e fatores relacionados aos hábitos de vida, devem ser o foco principal porque eles são os fatores de risco para FL ± P, não fatores relacionados ao domicílio em área carente.

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.

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.

Individual deprivation, regional deprivation, and risk for oral clefts in Argentina / Privación económica individual y regional, y riesgo de hendiduras orofaciales en Argentina / Carência individual, carência regional e risco de fissuras orais na Argentina

ABSTRACT 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.

RESUMEN Objetivo Analizar los efectos de un bajo nivel socioeconómico individual y una zona geográfica desfavorable en la aparición del labio leporino aislado con o sin paladar hendido (LL ± P) en Argentina. Métodos En este estudio de casos y controles se incluyeron 577 recién nacidos con LL ± P aislado y 13 344 controles sanos nacidos entre 1992 y 2001, de un total de 546 129 nacimientos ocurridos en 39 hospitales de Argentina. Para identificar las zonas geográficas desfavorables se utilizaron datos del Índice de Necesidades Básicas Insatisfechas. Se calculó un índice de nivel socioeconómico para cada participante usando la edad materna, el número de embarazos, el nivel de instrucción bajo del padre y la madre, y el nivel de ocupación bajo del padre. Se usó regresión logística para evaluar los efectos de un bajo nivel socioeconómico y una zona geográfica desfavorable en la ocurrencia de LL ± P. Resultados Se observó un riesgo levemente mayor de LL ± P en madres con bajo nivel socioeconómico, mientras que una zona geográfica desfavorable no mostró ningún efecto. La ascendencia indígena, las enfermedades agudas maternas y una atención prenatal deficiente fueron factores de riesgo significativos para LL ± P en madres con bajo nivel socioeconómico, después de ajustar las características demográficas de casos y controles mediante análisis de propensión. Conclusiones Un bajo nivel socioeconómico aumentó levemente el riesgo de LL ± P, pero una zona geográfica desfavorable no mostró ese efecto. No hubo interacción entre un bajo nivel socioeconómico individual y una zona geográfica desfavorable. Los factores relacionados con un bajo nivel socioeconómico individual —inclusive una atención prenatal deficiente, la baja educación de los padres, la falta de información y el estilo de vida— deben abordarse principalmente como factores de riesgo de LL ± P más que los factores relacionados con una zona de residencia desfavorable.

RESUMO Objetivo Examinar os efeitos do baixo nível socioeconômico individual e área geográfica em situação de carência na ocorrência de fissura labial isolada com ou sem fissura palatina (FL ± P) na Argentina. Métodos Estudo de caso-controle que compreendeu 577 recém-nascidos com FL isolada ± P e 13 344 controles saudáveis, nascidos entre 1992 e 2001, de uma população total de 546 129 nascimentos em 39 hospitais na Argentina. Foram usados dados censitários sobre necessidades básicas existentes para estabelecer o grau de carência das áreas geográficas. Foi determinado um índice de nível socioeconômico para cada indivíduo baseado na idade materna, número de gestações, baixa escolaridade materna e paterna e ocupação paterna de baixo nível. Foi realizada uma regressão logística para avaliar os efeitos do baixo nível socioeconômico e área geográfica em situação de carência na ocorrência de FL ± P. Resultados Observou-se um risco discretamente aumentado de FL ± P em mães com baixo nível socioeconômico, mas nenhum efeito foi verificado quanto à área geográfica em situação de carência. Descendência indígena, doença materna aguda e assistência pré-natal precária foram fatores de risco importantes para FL ± P nas mães com baixo nível socioeconômico, após o uso de escores de propensão para ajustar as características demográficas em casos e controles. Conclusões O baixo nível socioeconômico individual foi associado a um discreto aumento do risco de FL ± P, mas este efeito não foi observado para área geográfica em situação de carência. Não houve interação entre nível socioeconômico individual e área geográfica em situação de carência. Fatores relacionados ao baixo nível socioeconômico individual, como assistência pré-natal precária, baixa escolaridade dos pais, falta de informação e fatores relacionados aos hábitos de vida, devem ser o foco principal porque eles são os fatores de risco para FL ± P, não fatores relacionados ao domicílio em área carente.

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.

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.

Environmental risk factors and perinatal outcomes in preterm newborns, according to family recurrence of prematurity.

OBJECTIVE: We analyzed the role of environmental risk factors, sociodemographic characteristics, clinical characteristics, and reproductive history in preterm births and their associated perinatal outcomes in families classified according to their histories of preterm recurrence among siblings. STUDY DESIGN: A retrospective study was conducted at Nuestra Señora de la Merced Maternity Hospital in the city of Tucumán, Argentina. A total of 348 preterm, non-malformed, singleton children born to multipara women were reviewed. The family history score described by Khoury was applied, and families were classified as having no, medium, or high genetic aggregation. RESULTS: Families with no familial aggregation showed a higher rate of short length of cohabitation, maternal urinary tract infections during the current pregnancy, and maternal history of miscarriage during the previous pregnancy. Families with a high level of aggregation had a significantly higher incidence of pregnancy complications, such as diabetes, hypertension, and immunologic disorders. CONCLUSION: Reproductive histories clearly differed between the groups, suggesting both a different response to environmental challenges based on genetic susceptibility and the activation of different pathophysiological pathways to determine the duration of pregnancy in each woman.