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OBJECTIVE: This study aimed to examine the association between cervical length and the risk of adverse outcomes in placenta previa pregnancies. In addition, the diagnostic accuracy of cervical length in predicting emergency cesarean delivery due to hemorrhage was evaluated. DATA SOURCES: PubMed, Web of Science, and Embase were systematically searched up to January 21, 2023. STUDY ELIGIBILITY CRITERIA: Observational studies investigating the relationship between cervical length and maternal adverse outcomes in patients with placenta previa were considered eligible. The primary outcome was the diagnostic accuracy of cervical length measured at 28 to 34 weeks of gestation for the prediction of emergency cesarean delivery due to hemorrhage. The secondary outcomes were the probability of antenatal bleeding, preterm birth (both iatrogenic and spontaneous), and postpartum hemorrhage >2000 mL. Insufficient data were available on the transfusion procedure in cases where the cervical length was <30 mm. METHODS: For prognostic analysis, the random-effects model was used to pool the odds ratios and the corresponding 95% confidence intervals. For the diagnostic part, we used a summary receiver-operating characteristic curve, pooled sensitivities and specificities, area under the curve, and summary likelihood ratios. RESULTS: A total of 13 studies presenting data on 1462 pregnancies with placenta previa were included. Cervical length ≤30 mm at 28 to 34 weeks of gestation had a sensitivity of 61% (95% confidence interval, 43-77), specificity of 83% (95% confidence interval, 76-88), and area under the curve of 0.83 (95% confidence interval, 0.80-0.86) for the prediction of emergency cesarean delivery. Furthermore, cervical length ≤30 mm was associated with antenatal bleeding (odds ratio, 3.62; 95% confidence interval, 2.09-6.26; P<.001; I2=54.8%), preterm birth (odds ratio, 8.46; 95% confidence interval, 3.05-23.44; P<.001; I2=83.6%), and postpartum hemorrhage (odds ratio, 6.89; 95% confidence interval, 4.51-10.53; P<.001; I2=0.00%). CONCLUSION: Short cervical length (≤30 mm) measured at 28 to 34 weeks of gestation can assist in predicting the risk of emergency cesarean delivery due to hemorrhage in pregnancies with placenta previa. Furthermore, short cervical length is significantly associated with the risk of antenatal bleeding, preterm birth, and postpartum hemorrhage in pregnancies with placenta previa.
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INTRODUCTION: Caesarean section (C/S) rates have significantly increased across the world over the past decades. In the present population-based study, we sought to evaluate the association between C/S and neonatal mortality rates. MATERIAL AND METHODS: This retrospective ecological study included longitudinal data of 166 countries from 2000 to 2015. We evaluated the association between C/S rates and neonatal mortality rate (NMR), adjusting for total fertility rate, human development index (HDI), gross domestic product (GDP) percentage, and maternal age at first childbearing. The examinations were also performed considering different geographical regions as well as regions with different income levels. RESULTS: The C/S rate and NMR in the 166 included countries were 19.97% ± 10.56% and 10 ± 10.27 per 1000 live birth, respectively. After adjustment for confounding variables, C/S rate and NMR were found correlated (r = -1.1, p < 0.001). Examination of the relationship between C/S rate and NMR in each WHO region resulted in an inverse correlation in Africa (r = -0.75, p = 0.005), Europe (r = -0.12, p < 0.001), South-East Asia (r = -0.41, p = 0.01), and Western Pacific (r = -0.13, p = 0.02), a direct correlation in America (r = 0.06, p = 0.04), and no correlation in Eastern Mediterranean (r = 0.01, p = 0.88). Meanwhile, C/S rate and NMR were inversely associated in regions with upper-middle (r = -0.15, p < 0.001) and lower-middle (r = -0.24, p < 0.001) income levels, directly associated in high-income regions (r = 0.02, p = 0.001), and not associated in low-income regions (p = 0.13). In countries with HDI below the centralized value of 1 (the real value of 0.9), the correlation between C/S rate and NMR was negative while it was found positive in countries with HDI higher than the mentioned cut-off. CONCLUSIONS: This study indicated that NMR associated with C/S is dependent on various socioeconomic factors such as total fertility rate, HDI, GDP percentage, and maternal age at first childbearing. Further attentions to the socioeconomic status are warranted to minimize the NMR by modifying the C/S rate to the optimum cut-off.