Prediction of preterm birth in nulliparous patients

Risk Scoring Systems for Preterm Birth and Their Performance: A Systematic Review

Introduction: Nowadays, the risk stratification of preterm birth (PTB) and its prediction remain a challenge. Many risk factors associated with PTB have been identified, and risk scoring systems (RSSs) have been developed to face this challenge. The objectives of this systematic review were to identify RSSs for PTB, the variables they consist of, and their performance. Materials and methods: Two databases were searched, and two authors independently performed the screening and eligibility phases. Records studying an RSS, based on specified variables, with an evaluation of the predictive value for PTB, were considered eligible. Reference lists of eligible studies and review articles were also searched. Data from the included studies were extracted. Results: A total of 56 studies were included in this review. The most frequently incorporated variables in the RSS included in this review were maternal age, weight, history of smoking, history of previous PTB, and cervical length. The performance measures varied widely among the studies, with sensitivity ranging between 4.2% and 92.0% and area under the curve (AUC) between 0.59 and 0.95. Conclusions: Despite the recent technological and scientifical evolution with a better understanding of variables related to PTB and the definition of new ultrasonographic parameters and biomarkers associated with PTB, the RSS's ability to predict PTB remains poor in most situations, thus compromising the integration of a single RSS in clinical practice. The development of new RSSs, the identification of new variables associated with PTB, and the elaboration of a large reference dataset might be a step forward to tackle the problem of PTB.

Oxidative stress damage as a detrimental factor in preterm birth pathology

Normal term and spontaneous preterm births (PTB) are documented to be associated with oxidative stress (OS), and imbalances in the redox system (balance between pro- and antioxidant) have been reported in the maternal-fetal intrauterine compartments. The exact mechanism of labor initiation either at term or preterm by OS is still unclear, and this lack of understanding can partially be blamed for failure of antioxidant supplementation trials in PTB prevention. Based on recent findings from our laboratory, we postulate heterogeneity in host OS response. The physiologic (at term) and pathophysiologic (preterm) pathways of labor are not mediated by OS alone but by OS-induced damage to intrauterine tissues, especially fetal membranes of the placenta. OS damage affects all major cellular elements in the fetal cells, and this damage promotes fetal cell senescence (aging). The aging of the fetal cells is predominated by p38 mitogen activated kinase (p38MAPK) pathways. Senescing cells generate biomolecular signals that are uterotonic, triggering labor process. The aging of fetal cells is normal at term. However, aging is premature in PTB, especially in those PTBs complicated by preterm premature rupture of the membranes, where elements of redox imbalances and OS damage are more dominant. We postulate that fetal cell senescence signals generated by OS damage are likely triggers for labor. This review highlights the mechanisms involved in senescence development at term and preterm by OS damage and provides insight into novel fetal signals of labor initiation pathways.

Triggers of spontaneous preterm delivery--why today?

BACKGROUND

Our goal is to study the triggers of spontaneous preterm delivery using a case-crossover design.

METHODS

In a pilot study, we enrolled 50 women with spontaneous preterm labour (PTL) and 50 with preterm premature rupture of membranes (PPROM) between 2011 and 2012. To assess non-transient risk factors, we also enrolled a control group of 158 pregnant women at their regular prenatal care visits matched to cases by gestational age and calendar time. The index time was defined as the onset of PTL/PPROM (for cases) or interview (for controls). Detailed data were collected through structured interviews regarding factors of interest during the 72 h that preceded the index time. Within case subjects, we compared the frequency of transient factors from 0 to 24 h before index time with that from 48 to 72 h before index time, and estimated matched odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Previously hypothesised chronic risk factors for spontaneous preterm delivery, including mood disorders and stressful events, were more common among cases than among controls. Within cases, skipped meals [OR 4.3, 95% CI 1.2, 15.2], disturbed sleep [OR 4.5, 95% CI 1.5, 13.3], sexual activity [OR 6.0, 95% CI 0.7, 69.8], and intake of spicy foods [OR 7.0, 95% CI 1.6, 30.8] were associated with an increased risk for PTL/PPROM within the subsequent 24 h. For physical exertion and other potential risk factors evaluated, the OR was close to the null.

CONCLUSION

Skipping meals and disturbed sleep may be associated with imminent PTL/PPROM; sexual activity and spicy food may trigger PTL/PPROM in susceptible women. Larger case-crossover studies will be able to evaluate the impact of modifiable risk factors and acute predictors of PTL/PPROM, and might help guide obstetrical management.

Preventing low birth weight: is prenatal care the answer?

OBJECTIVES

To review the evidence of effectiveness of prenatal care for preventing low birth weight (LBW).

METHODS

We reviewed original research, systematic reviews, meta-analyses and commentaries for evidence of effectiveness of the three core components of prenatal care--risk assessment, health promotion and medical and psychosocial interventions--for preventing the two constituents of LBW: preterm birth and intrauterine growth restriction (IUGR).

RESULTS

Clinical risk assessment will fail to identify the majority of pregnancies at risk for preterm delivery or IUGR. While biophysical and biochemical modalities appear promising, their cost-effectiveness has not been demonstrated, nor can their routine use be recommended in the absence of effective interventions. Smoking cessation programs appear to be modestly effective. There is insufficient evidence to conclude a benefit for nutrition interventions, work counseling or preterm birth education. Only antenatal corticosteroid therapy has demonstrated a clear benefit in the tertiary prevention of preterm delivery. Interventions for which there is insufficient evidence to conclude a benefit include bed rest, hydration, sedation, cerclage, progesterone supplementation, antibiotic treatment, tocolysis without concomitant use of corticosteroids, thyrotropin-releasing hormone, psychosocial support and home visitation. Additionally, there is a paucity of evidence supporting the effectiveness of prenatal interventions, such as low-dose aspirin, bed rest, maternal hyperoxygenation, plasma volume expansion and antenatal fetal assessment, in preventing IUGR or its associated morbidity and mortality.

CONCLUSIONS

Neither preterm birth nor IUGR can be effectively prevented by prenatal care in its present form. Preventing LBW will require reconceptualization of prenatal care as part of a longitudinally and contextually integrated strategy to promote optimal development of women's reproductive health not only during pregnancy, but over the life course.

Patients with an ultrasonographic cervical length < or =15 mm have nearly a 50% risk of early spontaneous preterm delivery

OBJECTIVE

The aim of this study was to determine the value in the prediction of spontaneous preterm delivery of ultrasonographically measured cervical length measured between 14 and 24 weeks' gestation.

STUDY DESIGN

A retrospective cohort study examined cervical length by means of a two-stage procedure, transabdominal ultrasonography followed by transvaginal ultrasonography if cervical length was <30 mm.

RESULTS

A total of 6877 patients met inclusion criteria. Mean cervical length was 37.5 mm. Odds ratios for early preterm delivery (< or =32 weeks' gestation) for patients with cervical lengths < or =10, < or =15, < or = 20, < or =25, and < or =30 mm were, respectively, 29.3 (95% confidence interval, 11.3-75.8), 24.3 (95% confidence interval, 12. 9-45.9), 18.3 (95% confidence interval, 10.8-31.0), 13.4 (95% confidence interval, 8.8-20.6), and 3.2 (95% confidence interval, 2. 4-4.4). For early preterm delivery a cervical length of < or =15 mm had a positive predictive value of 47.6%, a negative predictive value of 96.7%, a sensitivity of 8.2%, and a specificity of 99.7%.

CONCLUSIONS

A short cervix seen on a second-trimester sonogram was a powerful predictor of early spontaneous preterm delivery (< or =32 weeks' gestation). Nearly 50% of patients with a cervical length < or =15 mm had an early spontaneous preterm delivery, which suggests that clinical trials of interventions (eg, cerclage) in this population are urgently needed.

Bacteriuria in pregnancy: a comparison of Bangladeshi and Caucasian women

During a 5-year period all urine culture results from pregnant Caucasian and Bangladeshi women booked for confinement at the Royal London Hospital, London, UK, were reviewed to determine race-specific rates of bacteriuria. The results showed that the overall prevalence of bacteriuria in the Caucasian group was 6.3% compared to 2.0% for the Bangladeshi women. Caucasian women were found to be at significantly greater risk across all pregnancy outcome and history categories, with the greatest risk observed in grand multiparous women (RR: 4.7, 95% CI: 2.8-8.3). Pregnancies that resulted in preterm delivery showed a strong association of bacteriuria in Caucasian women which was not seen in the Bangladeshi women (RR: 4.4, 95% CI: 2.0-8.7). The data suggest that Caucasian women have a significantly higher prevalence of bacteriuria in pregnancy than their Bangladeshi neighbors. Differences in hygiene practices and clothing may explain the observed differences in the bacteriuria rates.