The Risk of Preterm Birth in Women with Three Consecutive Deliveries-The Effect of Number and Type of Prior Preterm Births

Recurrent preterm birth: data from the study "Birth in Brazil"

OBJECTIVE

Describe and estimate the rate of recurrent preterm birth in Brazil according to the type of delivery, weighted by associated factors.

METHODS

We obtained data from the national hospital-based study "Birth in Brazil", conducted in 2011 and 2012, from interviews with 23,894 women. Initially, we used the chi-square test to verify the differences between newborns according to previous prematurity and type of recurrent prematurity. Sequentially, we applied the propensity score method to balance the groups according to the following covariates: maternal age, socio-economic status, smoking during pregnancy, parity, previous cesarean section, previous stillbirth or neonatal death, chronic hypertension and chronic diabetes. Finally, we performed multiple logistic regression to estimate the recorrence.

RESULTS

We analyzed 6,701 newborns. The rate of recurrence was 42.0%, considering all women with previous prematurity. Among the recurrent premature births, 62.2% were spontaneous and 37.8% were provider-initiated. After weighting by propensity score, we found that women with prematurity have 3.89 times the chance of having spontaneous recurrent preterm birth (ORaj = 3.89; 95%CI 3.01-5.03) and 3.47 times the chance of having provider-initiated recurrent preterm birth (ORaj = 3.47; 95%CI 2.59-4.66), compared to women who had full-term newborns.

CONCLUSIONS

Previous prematurity showed to be a strong predictor for its recurrence. Thus, expanding and improving the monitoring and management of pregnant women who had occurrence of prematurity strongly influence the reduction of rates and, consequently, the reduction of infant morbidity and mortality risks in the country.

Recurrent preterm birth risk assessment for two delivery subtypes: A multivariable analysis

OBJECTIVE

The study sought to develop and apply a framework that uses a clinical phenotyping tool to assess risk for recurrent preterm birth.

MATERIALS AND METHODS

We extended an existing clinical phenotyping tool and applied a 4-step framework for our retrospective cohort study. The study was based on data collected in the Genomic and Proteomic Network for Preterm Birth Research Longitudinal Cohort Study (GPN-PBR LS). A total of 52 sociodemographic, clinical and obstetric history-related risk factors were selected for the analysis. Spontaneous and indicated delivery subtypes were analyzed both individually and in combination. Chi-square analysis and Kaplan-Meier estimate were used for univariate analysis. A Cox proportional hazards model was used for multivariable analysis.

RESULTS

: A total of 428 women with a history of spontaneous preterm birth qualified for our analysis. The predictors of preterm delivery used in multivariable model were maternal age, maternal race, household income, marital status, previous caesarean section, number of previous deliveries, number of previous abortions, previous birth weight, cervical insufficiency, decidual hemorrhage, and placental dysfunction. The models stratified by delivery subtype performed better than the naïve model (concordance 0.76 for the spontaneous model, 0.87 for the indicated model, and 0.72 for the naïve model).

DISCUSSION

The proposed 4-step framework is effective to analyze risk factors for recurrent preterm birth in a retrospective cohort and possesses practical features for future analyses with other data sources (eg, electronic health record data).

CONCLUSIONS

We developed an analytical framework that utilizes a clinical phenotyping tool and performed a survival analysis to analyze risk for recurrent preterm birth.

Recurrent short interpregnancy interval: Maternal and neonatal outcomes

OBJECTIVE

To evaluate maternal and neonatal outcomes associated with recurrent short interpregnancy interval (IPI) in women in their third delivery.

METHODS

A retrospective computerized database study of all women who delivered their first three consecutive deliveries in a single tertiary medical center over 20 years (1999-2019). Maternal and neonatal outcomes of women with recurrent short IPI (<6 months between the 1st and 2nd pregnancy and the 2nd and 3rd pregnancy) were compared to women with recurrent optimal IPI (18-48 months), and to women with a single short IPI (<6 months between the 1st and 2nd pregnancy followed by an optimal IPI of 18-48 months between the 2nd and 3rd pregnancy). Additionally, in the recurrent short IPI groups, outcomes of the 2nd and 3rd pregnancies were compared in order to achieve an ideal adjustment to background characteristics. Univariate analysis was followed by multiple logistic regression models; adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

During the study period 10,569 women had three consecutive deliveries at our medical center, of those 338 (3.2%) women had recurrent short IPIs, and 1,021 (9.7%) had recurrent optimal IPIs. Recurrent short IPI was associated with a significantly higher risk of maternal anemia (Hb < 10gr%) on admission to labor (aOR 3.4 [95% CI 1.09-10.65], p = 0.04) and higher risk of small for gestational age neonates (aOR 10.4 [95% CI 2.32-46.93], p < 0.01), as compared with women with recurrent optimal IPI and significantly higher rates of low neonatal birth weights (2500 gr) and anemia (Hb < 10gr%) alongside lower rates of operative vaginal deliveries as compared with women with single short IPI followed by an optimal IPI. In the recurrent short IPI groups, the 3rd deliveries had significantly higher rates of in-labor cesarean and anemia (Hb < 10gr%) on admission as compared to their 2nd deliveries.

CONCLUSION

Recurrent short IPI is associated with maternal anemia and small for gestational age neonates. Guiding patients towards prolongation of the IPI should include explanatory comments on these outcomes.

Early term birth is associated with the risk of preterm and recurrent early term birth in women with 3 consecutive deliveries

BACKGROUND

We assessed the association of early term at first birth (ETB) with the risk of preterm birth (PTB) and ETB in women with 3 consecutive deliveries.

METHODS

We conducted a retrospective cohort study of all women with 3 consecutive singleton births at a single institute from 1994 to 2013. The risk of PTB (<37 weeks), spontaneous PTB and ETB (37-38 weeks) in the 3^rd delivery was explored.

RESULTS

Of 49,259 women delivered in our center during the study period, 4038 met inclusion criteria. The rate for subsequent PTB, spontaneous PTB and recurrent ETB in the 3^rd delivery significantly increased as the number of prior ETBs increased. The order of a single prior ETB in one of the first two deliveries was differently associated with the risk of complications in the 3^rd delivery, which was higher when the prior ETB was more recent to the third delivery.

CONCLUSION

A history of ETB is associated with the risk of future PTB and recurrent ETB. The risk is related to the number and order of prior ETBs.