Familial Spontaneous Preterm Birth: Further Evidence of a Complex Genetic Disease

Phenotypic Classification of preterm Birth Among Multiparous Women: A Population-Based Cohort Study

OBJECTIVE

The Global Alliance to Prevent Prematurity and Stillbirth developed a phenotypic classification for preterm birth using clinical presentation (rather than risk factors) to improve surveillance. The objective of this study was to determine distributions of preterm birth phenotypes and associations with Caesarean section, low Apgar score, and neonatal death in multiparous women, stratifying by first versus recurrent preterm births.

METHODS

This population-based cohort study used the Better Outcomes Registry and Network (BORN) of multiparous women giving birth in hospital with a singleton after 20 weeks in Ontario from 2012 to 2014 (Canadian Task Force Classification II-2).

RESULTS

In multiparous women with preterm birth, 29.6% had a history of recurrence, of whom 66.2% had at least one clinical condition associated with the phenotypic model, compared with 63.5% of first preterm births. In recurrent preterm births, criteria for maternal, fetal, and placental conditions were met in 44.5%, 37.9%, and 8.2%, respectively, compared with 36.8%, 39.0%, and 10.4%, respectively, of first preterm births. Associations of preterm birth with Caesarean section, low Apgar score, and neonatal death varied across clinical conditions but were similar between first and recurrent preterm births; for example, for recurrent preterm birth, Caesarean section for maternal, fetal, and placental conditions had odds ratios of 1.66 (95% confidence interval [CI] 1.32-2.07), 1.09 (95% CI 0.80-1.49), and 3.92 (95% CI 1.98-7.78), compared with first preterm birth odds ratios of 1.21 (95% CI 1.03-1.41), 0.92 (95% CI 0.77-1.10), and 6.24 (95% CI 4.07-9.56).

CONCLUSION

This study provides novel evidence of the utility of the preterm birth phenotypic classification model by using stratification for previous preterm birth, a robust predictor-with variation in phenotypes in initial and recurrent preterm births.

Prevalence of Autism Spectrum Disorders with and without Intellectual Disability by Gestational Age at Birth in the Stockholm Youth Cohort: a Register Linkage Study

BACKGROUND

Preterm birth has been linked to increased risk of autism spectrum disorders (ASD), but how this risk changes with gestational age at birth has not been well characterised, especially with regard to co-occurring intellectual disability (ID).

METHODS

Register-based cohort study of singleton births in 1984-2007 in Stockholm County, Sweden (N total: 480 728; n ASD: 10 025). We assessed overall and sex-specific, gestational week-specific prevalence estimates and risk ratios of ASD with and without ID.

RESULTS

Preterm and postterm births were associated with elevated risk of ASD, and the relationship between gestational age at birth and ASD with and without ID differed in males and females. Risk of ASD without ID was higher in preterm births among both sexes and decreased continuously with increasing length of gestation. Risk of ASD with ID was higher in both preterm and postterm births among both sexes, with postterm birth in females being more highly associated with ASD with ID than that in males.

CONCLUSIONS

The relationship between gestational age at birth and ASD differs by the presence/absence of co-occurring ID and fetal sex. Both preterm and postterm birth are associated with increased risk of ASD. Risk of ASD is not constant within conventionally defined gestational age at birth periods. Further research on mechanism underlying these associations is needed.

[Association between interleukin-1β C+3953T and genetic susceptibility to spontaneous preterm birth: a case-control study]

OBJECTIVE

To study the association between interleukin-1β (IL-1β) C+3953T and genetic susceptibility to spontaneous preterm birth (SPTB).

METHODS

In this case-control study, 753 SPTB neonates were enrolled in the case group and 681 full-term neonates were enrolled in the control group. The latest Sequenom MassARRAY®SNP detection technique was used for the typing of single nucleotide polymorphisms (SNP) of IL-1β C+3953T.

RESULTS

Compared with those carrying CC genotype of IL-1β C+3953T, the neonates who carried at least one T allele (CT+TT genotype) had significantly increased risks of SPTB, SPTB complicated by premature rupture of membranes, and mild preterm birth.

CONCLUSIONS

In the Chinese population, IL-1β C+3953T has significant genetic association with an increased risk of SPTB. The identification of this SNP helps to prevent SPTB and clarify the causes and pathogenesis of SPTB.

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.