The use of a comparability scoring system in reporting observational studies

Does cervical cerclage decrease preterm birth in twin pregnancies with a short cervix?

PURPOSE

To determine if use of cerclage in twin gestations with mid-trimester short cervix is associated with decreased preterm birth rate.

STUDY DESIGN

This is a retrospective cohort of twin gestations identified with cervical length of ≤2.5 cm before 24 weeks of gestation through the perinatal ultrasound database of two institutions from 2008 to 2014. Patients with and without cerclage were compared for a primary outcome of preterm birth at <35 weeks. A pre-planned sub-group analysis of patients with cervical length ≤1.5 cm was also performed.

RESULTS

Eighty-two patients were included; 43 received cerclage, 39 did not. Mean gestational age at cerclage placement was 20.8 weeks. There was no significant difference in rate of preterm birth <35 weeks between the groups (34.9% versus 48.7%, respectively). In the sub-group analysis of patients with cervical length ≤1.5 cm, there was a significant decreased risk of preterm birth <35 weeks [37% versus 71.4%; adjusted RR 0.49 (0.26-0.93)].

CONCLUSION

Cerclage placement for cervical length ≤2.5 cm in twin gestations did not decrease the rate of preterm birth at <35 weeks; however, cerclage placement for cervical length ≤1.5 cm was associated with a significantly decreased rate of preterm birth <35 weeks when compared to patients managed without cerclage.

Evaluating the impact of the laborist model of obstetric care on maternal and neonatal outcomes

BACKGROUND

The laborist model of obstetric care represents a change in care delivery with the potential of improving maternal and neonatal outcomes.

OBJECTIVE

We evaluated the effectiveness of the laborist model of care compared to the traditional model of obstetric care using specific maternal and neonatal outcome measures.

STUDY DESIGN

This is a population cohort study with laborist and nonlaborist hospitals matched 1:2 on delivery volume, geography, teaching status, and neonatal intensive care unit level using data from the National Perinatal Information Center/Quality Analytic Services database. A before-and-after study design with an untreated comparison group analyzed with the method of difference-in-differences was used to examine the impact of laborists on maternal and neonatal outcome measures within the 3 years after implementing the laborist system, after adjusting for secular trends, sociodemographic factors, and maternal medical conditions. The final outcome measures evaluated included cesarean delivery, chorioamnionitis, induction of labor, preterm birth, prolonged length of stay, Apgar at 5 minutes of <7, birth asphyxia, birth injury, birth trauma, and neonatal death.

RESULTS

We studied nearly 550,000 women from 24 hospitals (8 laborist and 16 nonlaborist hospitals) from 1998 through 2011. Implementation of laborists was associated with fewer labor inductions (adjusted odds ratio, 0.85; 95% confidence interval, 0.71-0.99) and decreased rate of preterm birth (adjusted odds ratio, 0.83; 95% confidence interval, 0.72-0.96) after controlling for confounders. Laborists did not impact the cesarean delivery rate, chorioamnionitis, or prolonged length of stay.

CONCLUSION

Implementation of the laborist model was associated with a significant reduction in labor induction rate and preterm birth without adversely affecting other outcomes.

Vaginal progesterone combined with cervical pessary: A chance for pregnancies at risk for preterm birth?

BACKGROUND

Precocious cervical ripening, as defined by cervical shortening on transvaginal sonography, has prompted a broad evaluation of secondary strategies (such as cerclage, vaginal progesterone, or a cervical pessary) to prevent preterm delivery. However, there is still a lack of direct comparisons between individual treatments or their combinations.

OBJECTIVE

We sought to compare at-risk patients and screening patients who had been treated with cervical pessary alone with patients who had been treated with pessary plus vaginal progesterone.

STUDY DESIGN

This is a pre- and postintervention cohort study from a preterm labor clinic where placement of a cervical pessary has been the standard treatment since 2008 for at-risk women defined by (1) a history of spontaneous preterm birth at <37 weeks of gestation, (2) conization, or (3) a cerclage because of a previous short cervical length of <3rd percentile and, additionally, with a cervical length of <10th percentile in the ongoing pregnancy. Patients who did not meet the criteria for the "at risk" group, but who had a cervical length of <3rd percentile comprised the screening group. From July 2011 onward, vaginal progesterone (200 mg, suppositories) was prescribed in addition to the pessary. Both at-risk patients (n = 55) and screening patients (n = 51) were treated at the time of diagnosis. The primary outcome was the rate of preterm deliveries at <34 weeks of gestation. Secondary outcomes included deliveries at <28, <32, and <37 weeks of gestation, the days from start of therapy until delivery, a composite index of neonatal outcome, and the number of days in the neonatal intensive care unit. Primary and secondary outcomes were compared between groups with the use of multivariable models to adjust for possible confounders.

RESULTS

Delivery at <34 weeks of gestation occurred in 17 of 53 patients (32.1%) who were treated with pessary plus progesterone, compared with 13 of 53 patients (24.5%) who were treated with pessary alone (P = .57). Similarly, there was no difference in the rate of preterm delivery at <28, <32, or <37 weeks of gestation. The composite poor neonatal outcome was 15.1% in the pessary group vs 18.9% in the combined group (P = .96). The mean duration of stay in the neonatal intensive care unit was 46.5 days (range, 9-130 days) in the combined vs 52.0 days (range, 3-151 days) in the pessary group (P < .001).

CONCLUSION

In this cohort study, treatment of precocious cervical ripening with cervical pessary plus vaginal progesterone did not reduce the rates of preterm delivery at <28, <32, <34, or <37 weeks of gestation compared with pessary alone. The neonatal intensive care use was shorter in patients who received additional vaginal progesterone, although there was no difference in composite poor neonatal outcome. These preliminary results may serve as a pilot for future trials and provide a basis for treatment until larger trials are completed.

Risk of Pregnancy Complications in Relation to Maternal Prepregnancy Body Mass Index: Population-Based Study from Finland 2006-10

BACKGROUND

Overweight and obesity are well-known risk factors for several pregnancy-related complications, but the nature of the association between maternal adiposity and these complications has been less studied. The objective of the present study was to examine the shape and the magnitude of the association between maternal prepregnancy body mass index and the risk of gestational diabetes, pre-eclampsia of different severity, gestational hypertension, and obstetric cholestasis among Finnish primiparae women.

METHODS

Data on all primiparae women who delivered a singleton newborn in Finland between 2006 and 2010 were identified from the Finnish Medical Birth Register and the Finnish Hospital Discharge Register (n = 119 485). Associations were analysed using restricted cubic spline regression and logistic regression models.

RESULTS

There was a nonlinear dose-dependent association between body mass index and the risk of gestational diabetes, pre-eclampsia, and gestational hypertension, and the risk was increased already among normal weight primiparae women. However, in the presence of pre-existing hypertension or diabetes body mass index was not associated with the risk of pre-eclampsia.

CONCLUSIONS

Efforts to reduce prepregnancy overweight and obesity need to be intensified, and also, measures to better identify those normal weight women who are at increased risk of gestational diabetes, pre-eclampsia and gestational hypertension should be developed.

Birth Outcomes of Latin Americans in Two Countries with Contrasting Immigration Admission Policies: Canada and Spain

Background

We delved into the selective migration hypothesis on health by comparing birth outcomes of Latin American immigrants giving birth in two receiving countries with dissimilar immigration admission policies: Canada and Spain. We hypothesized that a stronger immigrant selection in Canada will reflect more favourable outcomes among Latin Americans giving birth in Canada than among their counterparts giving birth in Spain.

Materials and Methods

We conducted a cross-sectional bi-national comparative study. We analyzed birth data of singleton infants born in Canada (2000–2005) (N = 31,767) and Spain (1998–2007) (N = 150,405) to mothers born in Spanish-speaking Latin American countries. We compared mean birthweight at 37–41 weeks gestation, and low birthweight and preterm birth rates between Latin American immigrants to Canada vs. Spain. Regression analysis for aggregate data was used to obtain Odds Ratios and Mean birthweight differences adjusted for infant sex, maternal age, parity, marital status, and father born in same source country.

Results

Latin American women in Canada had heavier newborns than their same-country counterparts giving birth in Spain, overall [adjusted mean birthweight difference: 101 grams; 95% confidence interval (CI): 98, 104], and within each maternal country of origin. Latin American women in Canada had fewer low birthweight and preterm infants than those giving birth in Spain [adjusted Odds Ratio: 0.88; 95% CI: 0.82, 0.94 for low birthweight, and 0.88; 95% CI: 0.84, 0.93 for preterm birth, respectively].

Conclusion

Latin American immigrant women had better birth outcomes in Canada than in Spain, suggesting a more selective migration in Canada than in Spain.

The timing of administration of antenatal corticosteroids in women with indicated preterm birth

OBJECTIVE

We sought to determine the timing of administration of antenatal corticosteroids (AS) for indicated preterm births and to identify which indications are associated with the most optimal timing of administration.

STUDY DESIGN

This was a retrospective cohort of patients who received AS in anticipation of indicated preterm birth from 2009 through 2012 at Winthrop University Hospital, Mineola, NY. Medical records of patients who received AS, as identified through the hospital pharmacy database, were reviewed. Patients were included if they had a singleton or twin gestation and they received AS for maternal or fetal indications. Women were excluded if they received AS for spontaneous preterm labor or preterm rupture of membranes. Maternal demographic and obstetrical characteristics were compared between those who received AS≤7 days vs >7 days from delivery using parametric and nonparametric tests with relative risks and 95% confidence intervals. P<.05 was considered significant.

RESULTS

In all, 193 patients were included in this study. Median latency from AS administration to delivery was 9 days (range, 0-83); 93 patients (48%) received AS within 7 days of delivery. There were no significant differences between the 2 groups with regards to baseline maternal characteristics. Those delivering within 7 days of AS administration were more likely to have maternal vs fetal indications (84% vs 16%).

CONCLUSION

Only 48% of patients with an indication for preterm birth received AS within 7 days of its administration. AS appear to be more optimally timed in the presence of maternal rather than fetal indications.

Severe maternal morbidity associated with maternal birthplace in three high-immigration settings

Background: Maternal mortality and morbidity vary substantially worldwide. It is unknown if these geographic differences translate into disparities in severe maternal morbidity among immigrants from various world regions. We assessed disparities in severe maternal morbidity between immigrant women from various world regions giving birth in three high-immigration countries. Methods: We used population-based delivery data from Victoria; Australia and Ontario, Canada and national data from Denmark, in the most recent 10-year period ending in 2010 available to each participating centre. Each centre provided aggregate data according to standardized definitions of the outcome, maternal regions of birth and covariates for pooled analyses. We used random effects and stratified logistic regression to obtain odds ratios (ORs) with 95% confidence intervals (95% CIs), adjusted for maternal age, parity and comparability scores. Results: We retrieved 2,322,907 deliveries in all three receiving countries, of which 479,986 (21%) were to immigrant women. Compared with non-immigrants, only Sub-Saharan African women were consistently at higher risk of severe maternal morbidity in all three receiving countries (pooled adjusted OR: 1.67; 95% CI: 1.43, 1.95). In contrast, both Western and Eastern European immigrants had lower odds (OR: 0.82; 95% CI: 0.70, 0.96 and OR: 0.64; 95% CI: 0.49, 0.83, respectively). The most common diagnosis was severe pre-eclampsia followed by uterine rupture, which was more common among Sub-Saharan Africans in all three settings. Conclusions: Immigrant women from Sub-Saharan Africa have higher rates of severe maternal morbidity. Other immigrant groups had similar or lower rates than the majority locally born populations.

Epidural analgesia in labour and risk of caesarean delivery

BACKGROUND

A Cochrane Systematic Review of randomised controlled trials of epidural analgesia compared with other or no analgesia in labour reported no overall increased risk of caesarean delivery. However, many trials were affected by substantial non-compliance, and there are concerns about the external validity of some trials for contemporary maternity populations. We aimed to explore the association between epidural analgesia in labour and caesarean delivery in clinical practice and compare with findings from randomised controlled trials.

METHODS

Population-based cohort of pregnant women (n = 210 708) without major obstetrical complications who delivered a singleton live infant in hospitals in New South Wales, Australia, 2007-10. Data were obtained from linked, validated population-based data collections. Propensity score matching was used to examine the association between epidural analgesia in labour and caesarean delivery.

RESULTS

Epidural analgesia in labour was used by a third (31.5%, n = 66 317) of the women, and 9.8% (n = 20 531) had a caesarean delivery. Epidural analgesia in labour was associated with increased risk of caesarean delivery {risk ratio [RR] 2.5, [95% confidence interval (CI) 2.5, 2.6]}. The association with epidural analgesia in labour was higher for caesarean delivery for failure to progress {RR 3.0, [95% CI 2.9, 3.0]} than for caesarean delivery for fetal distress {RR 1.9, [95% CI 1.8, 2.0]}.

CONCLUSIONS

Epidural analgesia in labour is associated with caesarean delivery in a large maternity population. Population-based studies contribute important data about obstetrical care, when research settings and participants may not represent the clinical settings or broader population in which obstetrical interventions in labour are applied.