Universal Cervical Length Screening and Antenatal Corticosteroid Timing

Routine screening of abnormal vaginal flora during pregnancy reduces the odds of preterm birth: a systematic review and meta-analysis

Prematurity is the leading cause of perinatal mortality and the morbidity among children under the age of 5. The prevalence of preterm birth is between 5 and 18% worldwide. Approximately 30% of preterm deliveries occur as a consequence of fetal or maternal infections. Bacterial vaginosis can increase the risk of ascending infections. However, there is no recommendation or protocol for screening of abnormal vaginal flora. The aim of this systematic review was to investigate the effectiveness of routine screening of abnormal vaginal flora during pregnancy care. We conducted our systematic search in the following databases: MEDLINE via PubMed, Embase, and Cochrane Library. Studies reporting on pregnant women with no symptoms of bacterial vaginosis were included in our analysis if they provided data on the outcome of their pregnancy. The intervention group went through screening of abnormal vaginal flora in addition to routine pregnancy care. Odds ratio (OR) with 95% confidence intervals (CIs) was used as effect size measure. From each study the total number of patients and number of events was extracted in both the intervention and control arm to calculate OR. Altogether we included 13 trials with 143,534 patients. The screening methods were Gram stain, pH screening, pH self-screening and pH screening combined with Gram stain. Regular screening of vaginal flora compared to no screening significantly reduces the odds of preterm birth before 37 weeks (8.98% vs 9.42%; OR 0.71, CI 0.57-0.87), birthweight under 2500 g (6.53% vs 7.24%; OR 0.64, CI 0.50-0.81), preterm birth before 32 weeks (1.35% vs 2.03%; OR 0.51, CI 0.31-0.85) and birthweight under 1000 g (0.86% vs 2.2%; OR 0.33, CI 0.19-0.57). In conclusion, the routine screening of abnormal vaginal flora might prevent preterm birth, extreme preterm birth, low birthweight deliveries and very low birthweight deliveries. Further research is needed to assess the problem more accurately.

Timing of antenatal corticosteroids in relation to clinical indication

PURPOSE

This study aimed at determining the proportion of women who receive antenatal corticosteroids (ACS) within the optimal time window before birth based on the indication for ACS, and to explore in more detail indications that are associated with suboptimal timing.

METHODS

A retrospective cohort study of all women who received ACS in a single tertiary center between 2014 and 2017. The primary outcome was an ACS-to-birth interval ≤ 7 days. Secondary outcomes were ACS-to-birth interval of ≤ 14 days, and the proportion women who received ACS but ultimately gave birth at term (≥ 37^0/7 weeks). The study outcomes were stratified by the clinical indication for ACS.

RESULTS

A total of 1261 women met the study criteria, of whom 401 (31.8%) and 569 (45.1%) received ACS within ≤ 7 days and ≤ 14 days before birth, respectively, and 203 (16.1%) ultimately gave birth at term. The proportion of women who received ACS within 7 days before birth was highest for women with preeclampsia (50.4%), and was lowest for women with an incidental finding of a short cervix (8.4%). In the subgroup of women with an incidental finding of a short cervix, the likelihood of optimal timing was not related to the magnitude of cervical shortening, history of preterm birth, multifetal gestation, presence of cervical funneling, or the presence of cervical cerclage.

CONCLUSION

Over two-thirds of infants who are exposed to ACS do not get the maximal benefit from this intervention. The current study identified clinical indications for ACS that are associated with suboptimal timing of ACS where more research is needed to develop quantitative, indication-specific prediction models to guide the timing of ACS.

Availability and use of fetal fibronectin testing and transvaginal ultrasound for preterm labor evaluation in the United States

OBJECTIVE

Measure availability and use of fetal fibronectin (fFN) testing and transvaginal ultrasound to measure cervical length (TVCL) for symptomatic preterm labor (PTL) patients. Additionally, assess the presence and impact of PTL triage protocols.

STUDY DESIGN

Cross-sectional online survey among clinicians from 255 unique hospitals regarding prior 12-month practices (pre-COVID-19).

RESULTS

fFN testing was always available in 87% (221) of hospitals, while TVCL was always available in 69% (175) of hospitals. Utilization was lower: fFN specimens were often/always collected in 61% (156) of hospitals and TVCL was often/always performed in 43% (110) of hospitals. fFN testing was significantly more likely than TVCL to be available and used (p < .05). Written PTL protocols were available in 47% (121) of hospitals but not consistently followed.

CONCLUSION

The most accurate risk assessment approach for imminent spontaneous preterm birth is the implementation of a universal screening program for symptomatic patients, including fFN testing and TVCL.

The Impact of Previous Obstetric History on the Risk of Spontaneous Preterm Birth in Women with a Sonographic Short Cervix

OBJECTIVE

The natural history of women with a short cervix and a low-risk obstetric history remains poorly defined. In our study, we sought to better characterize the impact of previous obstetric history on the delivery outcomes in women diagnosed with a mid-trimester sonographic short cervix.

STUDY DESIGN

We performed a retrospective cohort study of women with singleton gestations who underwent transvaginal cervical length screening between 16 and 24 weeks at two urban hospitals in Philadelphia between January 2013 and March 2018 and were found to have a short cervix (defined as ≤2 cm). Women were excluded from the cohort if there were major fetal anomalies noted or if delivery outcome information was not available. The cohort was then divided into three groups based on obstetric history: nulliparous, history of full-term birth only, or history of spontaneous preterm birth (sPTB). The primary outcome was sPTB <37 weeks, while the secondary outcome was sPTB <34 weeks.

RESULTS

Our cohort included a total of 384 singleton pregnancies that were diagnosed with a sonographic short cervix: 165 women were nulliparous, 119 women had a history of full-term birth, and 100 women with a history of sPTB. We found that women with a short sonographic cervix had a sPTB rate of 39.6% with no differences found between the three groups. Only two-thirds of nulliparous women and women with a history of full-term birth received the recommended preventative treatment, compared with almost 100% of women with a history of sPTB.

CONCLUSION

Women with and without a history of sPTB are at comparable risk of sPTB in the presence of a sonographically short cervix. Preventative therapies should be recommended to both nulliparous women and women with a history of full-term birth since uptake in this population are not as high.

The utility of fetal fibronectin in asymptomatic singleton and twin pregnancies with a cervical length ≤ 10 mm

Objective: To examine the utility of fetal fibronectin (fFN) for predicting spontaneous preterm birth (PTB) in asymptomatic women with a cervical length (CL) ≤10 mm compared to those with a CL 11-25 mm.Methods: Data was collected on all women with nonanomalous singleton and twin gestations who underwent transvaginal CL at a single institution between 2009 and 2012. Women with an incidental short cervix (CL ≤ 25 mm) between 22 and 32 weeks who had an fFN result within 7 days thereafter were included. Indicated preterm deliveries at <14 days of fFN, women who underwent cerclage placement, and terminations of pregnancy were excluded. The primary outcome was spontaneous PTB within 7 and 14 days of the fFN. Sensitivity, specificity, and positive (PPV) and negative predictive value (NPV) of fFN for a CL ≤ 10 mm was calculated for singletons and twins and compared to those with a CL 11-25 mm.Results: Of the 213 women included, 117 (54.9%) were singletons and 96 (45%) were twins. Baseline characteristics were similar between those with a CL ≤ 10 mm and with a CL 11-25 mm in both singletons and twins. The NPV of fFN for delivery within 7 days in singletons and twins with a CL ≤ 10 mm was 100%, similar to those with a CL 11-25 mm (93-100%). The NPV of fFN for delivery within 14 days in singletons and twins with a CL ≤ 10 mm remained high (87.5-100%) when compared to those with a CL 11-25 mm (93-100%). The PPV of fFN for delivery within 7 and 14 days in both singletons and twins with a CL ≤ 10 mm was low (10-25%) and similar to those with a CL 11-25 mm (7.1-24.4%).Conclusions: The NPV of fFN in asymptomatic singleton and twin pregnancies with a CL ≤ 10 mm is high and comparable to the NPV of fFN in women with a longer CL. Routine fFN collection in this select population should be considered as it may avoid unnecessary and costly admissions, as well as assist with timing of antenatal corticosteroids.

The risk of spontaneous preterm birth in asymptomatic women with a short cervix (≤25 mm) at 23-28 weeks' gestation

BACKGROUND

Asymptomatic short cervical length is an independent risk factor for spontaneous preterm birth. However, most studies have focused on the associated risk of a short cervical length when encountered between 16 and 23 weeks' gestation. The relationship between cervical length and risk of spontaneous preterm birth after 23 weeks is not well known.

OBJECTIVE

To evaluate the risk of spontaneous preterm birth in asymptomatic women with a short cervix (≤25 mm) at 23-28 weeks' gestation.

MATERIALS AND METHODS

A retrospective cohort study of women with asymptomatic short cervix (cervical length ≤25 mm) at extreme prematurity, defined as 23-28 weeks' gestation, was performed at a single center from January 2015 to March 2018. Women with symptoms of preterm labor, multiple gestations, fetal or uterine anomalies, cervical cerclage, or those with incomplete data were excluded from the study. Demographic information as well as data on risk factors for spontaneous preterm birth were collected. Patients were divided into 4 groups based on the cervical length measurement (≤10 mm, 11-15 mm, 16-20 mm, and 21-25 mm). The primary outcome was time interval from enrollment to delivery. Secondary outcomes included delivery within 1 and 2 weeks of enrollment, gestational age at delivery, and delivery prior to 32, 34, and 37 weeks, respectively. Continuous variables were compared using Kruskal-Wallis test, whereas categorical variables were compared using the χ² or Fisher exact test as appropriate. The Wilcoxon test for difference in survival time was used to compare gestational age at delivery among the 4 cervical length groups, with data stratified based on gestational age at enrollment.

RESULTS

Of the 126 pregnancies that met inclusion criteria, 22 (17.4%) had a cervical length of ≤10 mm, 23 (18.3%) had a cervical length of 11-15 mm, 37 (29.4%) had a cervical length of 16-20 mm, and 44 (34.9%) had a cervical length of 21-25 mm. Baseline characteristics were similar among all 4 groups. The shorter cervical length group was associated with a shorter time interval from enrollment to delivery (cervical length ≤10 mm, 10 weeks; cervical length 11-15 mm, 12.7 weeks; cervical length of 16-20 mm, 13 weeks; cervical length of 21-25 mm, 13.2 weeks; P = .006). Regardless of the cervical length measurement, delivery within 2 weeks was extremely uncommon (1 patient; 0.8%). The prevalence of spontaneous preterm birth at <32 weeks or <34 weeks was higher in women with a cervical length of ≤10 mm compared to those with a longer cervical length (P < .001).

CONCLUSIONS

The risk of spontaneous preterm birth in asymptomatic women with a sonographic short cervix increases as cervical length decreases. The risk is substantially higher in women with a cervical length of ≤10 mm. Women with a cervical length of ≤10 mm also had the shortest time interval to delivery. Nevertheless, delivery within 1 or 2 weeks is highly unlikely, regardless of the cervical length at the time of enrollment. Therefore, based on our data, we suggest that management decisions such as timing of administration of antenatal corticosteroids in asymptomatic patients with a cervical length of ≤25 mm at 23-28 weeks' gestation may be delayed until additional indications are present.

Missed opportunities for optimal antenatal corticosteroid timing in medically indicated preterm births

OBJECTIVE

Although delivery timing is physician dictated in indicated preterm births, suboptimal antenatal corticosteroids (ACS) administration occurs in most cases. We aimed to characterize the patterns of use of ACS in indicated preterm births and identify missed opportunities of optimal ACS administration.

METHODS

We reviewed the records of women who received ACS and were delivered due to maternal or fetal indications at 24-34 weeks of gestation during 2015-2017 at a university hospital. Optimal ACS timing was defined as delivery ≥24 h ≤7 d from the previous ACS course.

RESULTS

Overall, 188 pregnancies were included. The median gestational age at delivery was 32 weeks. Considering only the initial ACS course, the rate of optimal timing was 32.4%. Of 105 (55.8%) women eligible (delivery >7 d since the initial ACS course), only a third (n = 38) received a rescue ACS course. Among women who did not receive rescue ACS course despite their eligibility (n = 67), the decision-to-delivery was ≥3 h in 36 (53.7%), and ≥24 h in 20 (29.9%), representing 19.1 and 10.6% of the entire cohort, respectively. The urgency of the decision to deliver (i.e. in the upcoming 24 h and later) and allowing a trial of labor, were both positively associated with decision-to-delivery interval ≥3 h and ≥24 h. The rate of delivery within any optimal window (either initial or rescue course) was 40.4%, with gestational hypertensive disorders (OR [95% CI]: 2.40 (1.23, 4.72), p = .01) and decision to deliver made at first hospitalization (OR [95% CI]: 2.27 (1.04, 4.76), p = .04) as independent positive predictors of optimal ACS timing. The rate of composite adverse neonatal outcome was significantly lower in those with optimal ACS administration as compared to those with suboptimal timing (32.9 versus 50.9%, OR [95% CI]: 0.47 (0.26, 0.87), p = .02).

CONCLUSIONS

Suboptimal ACS administration occurred in most indicated preterm births. Underutilization of rescue ACS course and a substantial rate of missed opportunities for optimal ACS administration were identified as potentially modifiable contributors to improve ACS timing.

Labor estimation by informational objective assessment (LEIOA) for preterm delivery prediction

PURPOSE

To introduce LEIOA, a new screening method to forecast which patients admitted to the hospital because of suspected threatened premature delivery will give birth in < 7 days, so that it can be used to assist in the prognosis and treatment jointly with other clinical tools.

METHODS

From 2010 to 2013, 286 tocographies from women with gestational ages comprehended between 24 and 37 weeks were collected and studied. Then, we developed a new predictive model based on uterine contractions which combine the Generalized Hurst Exponent and the Approximate Entropy by logistic regression (LEIOA model). We compared it with a model using exclusively obstetric variables, and afterwards, we joined both to evaluate the gain. Finally, a cross validation was performed.

RESULTS

The combination of LEIOA with the medical model resulted in an increase (in average) of predictive values of 12% with respect to the medical model alone, giving a sensitivity of 0.937, a specificity of 0.747, a positive predictive value of 0.907 and a negative predictive value of 0.819. Besides, adding LEIOA reduced the percentage of incorrectly classified cases by the medical model by almost 50%.

CONCLUSIONS

Due to the significant increase in predictive parameters and the reduction of incorrectly classified cases when LEIOA was combined with the medical variables, we conclude that it could be a very useful tool to improve the estimation of the immediacy of preterm delivery.