Risk factors for post-partum hemorrhage following vacuum assisted vaginal delivery

Is Grand Multiparity an Independent Risk Factor for Blood Transfusion?

The relation between grand multiparity and poor pregnancy outcome, especially postpartum hemorrhage and blood transfusion, has displayed inconsistent findings. Some studies have identified an increased maternal and neonatal morbidity, but the more recent literature is less clear about the risks. The objective of the study is to determine the association of grand multiparity with postpartum blood transfusion. We conducted a retrospective cohort study in a single tertiary university-affiliated medical center between 2011 and 2019. All women were categorized into one of three groups based on the number of previous deliveries: (a) nulliparous (no previous delivery), (b) multiparous (1-4 previous deliveries), and (c) grand multiparous (≥ 5 previous deliveries). We compared the demographic, clinical, and pregnancy outcomes of the study groups. The primary outcome was the need for red blood cell transfusion during the index admission. During the study period, there were 87,343 deliveries in our center. Among the study population, 36,777 (42.1%) were nulliparous, 49,072 (56.1%) were multipara, and 1494 (1.7%) were grand multiparous. Overall, 1602 women (1.8%) were treated with RBC transfusion. Cesarean delivery, macrosomia, preterm delivery, multiple gestations, antenatal anemia, thrombocytopenia, intrauterine fetal death (IUFD), and prolonged second or third stage of labor were more prevalent among women who were treated with RBC transfusion. After controlling for potential confounders, including maternal age, preterm delivery, IUFD, mode of delivery, and antenatal thrombocytopenia, grand multiparity was found to be an independent protective factor for RBC transfusion (RR = 0.2 (0.007-0.56). After controlling for cofounders, grand multiparity alone is not associated with postpartum blood transfusion.

Induction of labor and risk of postpartum hemorrhage in women with vaginal delivery: A propensity score analysis

OBJECTIVE

To explore the association between induction of labor (IOL) and postpartum hemorrhage (PPH) after vaginal delivery.

METHODS

We included women from the merged database of three randomized prospective trials (TRACOR, CYTOCINON, and TRAAP) that measured postpartum blood loss precisely, with standardized methods. IOL was considered overall and according to its method. The association between IOL and PPH was tested by multivariate logistic regression modeling, adjusted for confounders, and by propensity score matching. The role of potential intermediate factors, i.e. estimated quantity of oxytocin administered during labor and operative vaginal delivery, was assessed with structural equation modeling.

RESULTS

Labor was induced for 1809 of the 9209 (19.6%) women. IOL was associated with a significantly higher risk of PPH of 500 mL or more (adjusted odds ratio 1.56, 95% confidence interval 1.42-1.70) and PPH of 1000 mL or more (adjusted odds ratio 1.51, 95% confidence interval 1.16-1.96). The risk of PPH increased similarly regardless of the method of induction. The results were similar after propensity score matching (odds ratio for PPH ≥500 mL 1.57, 95% confidence interval 1.33-1.87, odds ratio for PPH ≥1000 mL 1.57, 95% confidence interval 1.06-2.07). Structural equation modeling showed that 34% of this association was mediated by the quantity of oxytocin administered during labor and 1.3% by women who underwent operative vaginal delivery.

CONCLUSION

Among women with vaginal delivery, the risk of PPH is higher in those with IOL, regardless of its method, and after accounting for indication bias. The quantity of oxytocin administered during labor may explain one third of this association.

Postpartum haemorrhage occurring in UK midwifery units: A national population-based case-control study to investigate incidence, risk factors and outcomes

OBJECTIVES

To estimate the incidence of, and investigate risk factors for, postpartum haemorrhage (PPH) requiring transfer to obstetric care following birth in midwifery units (MU) in the UK; to describe outcomes for women who experience PPH requiring transfer to obstetric care.

METHODS

We conducted a national population-based case-control study in all MUs in the UK using the UK Midwifery Study System (UKMidSS). Between September 2019 and February 2020, 1501 women with PPH requiring transfer to obstetric care following birth in an MU, and 1475 control women were identified. We used multivariable logistic regression, generating adjusted odds ratios (aORs) and 95% confidence intervals (CIs) to investigate risk factors for PPH requiring transfer to obstetric care.

RESULTS

The incidence of PPH requiring transfer to obstetric care following birth in an MU was 3.7% (95% CI 3.6%-3.9%). Factors independently associated with PPH requiring transfer to obstetric care were smoking during pregnancy (aOR = 0.73; 95% CI 0.56-0.94), nulliparity (aOR = 1.96; 95% CI 1.66-2.30), previous PPH (aOR = 2.67; 95% CI 1.67-4.25), complications in a previous pregnancy other than PPH (aOR = 2.40; 95% CI 1.25-4.60), gestational age ≥41 weeks (aOR = 1.36; 95% CI 1.10-1.69), instrumental birth (aOR = 2.69; 95% CI 1.53-4.72), third stage of labour ≥60 minutes (aOR = 5.56; 95% CI 3.93-7.88), perineal trauma (aOR = 4.67; 95% CI 3.16-6.90), and birthweight 3500-3999g (aOR = 1.71; 95% CI 1.42-2.07) or ≥4000g (aOR = 2.31; 95% CI 1.78-3.00). One in ten (10.6%) cases received a blood transfusion and one in five (21.0%) were admitted to higher level care.

CONCLUSIONS

The risk factors identified in this study align with those identified in previous research and with current guidelines for women planning birth in an MU in the UK. Maternal outcomes after PPH were broadly reassuring and indicative of appropriate management. NHS organisations should ensure that robust guidelines are in place to support management of PPH in MUs.

Prediction of postpartum hemorrhage using traditional statistical analysis and a machine learning approach

BACKGROUND

Early detection of postpartum hemorrhage risk factors by healthcare providers during pregnancy and the postpartum period may allow healthcare providers to act to prevent it. Developing a prediction model that incorporates several risk factors and accurately calculates the overall risk for postpartum hemorrhage is necessary.

OBJECTIVE

This study used a traditional analytical approach and a machine learning model to predict postpartum hemorrhage.

STUDY DESIGN

Women who gave birth at the Khaleej-e-Fars Hospital in Bandar Abbas, Iran, were evaluated retrospectively between January 1, 2020, and January 1, 2022. These pregnant women were divided into 2 groups, namely those who had postpartum hemorrhage and those who did not. We used 2 approaches for the analysis. At the first level, we used the traditional analysis methods. Demographic factors, maternal comorbidities, and obstetrical factors were compared between the 2 groups. A bivariate logistic regression analysis of the risk factors for postpartum hemorrhage was done to estimate the crude odds ratios and their 95% confidence intervals. In the second level, we used machine learning approaches to predict postpartum hemorrhage.

RESULTS

Of the 8888 deliveries, we identified 163 women with recorded postpartum hemorrhage, giving a frequency of 1.8%. According to a traditional analysis, factors associated with an increased risk for postpartum hemorrhage in a bivariate logistic regression analysis were living in a rural area (odds ratio, 1.41; 95% confidence interval, 1.08-1.98); primiparity (odds ratio, 3.16; 95% confidence interval, 1.90-4.75); mild to moderate anemia (odds ratio, 5.94; 95% confidence interval 2.81-8.34); severe anemia (odds ratio, 6.01; 95% confidence interval 3.89-11.09); abnormal placentation (odds ratio, 7.66; 95% confidence interval, 2.81-17.34); fetal macrosomia (odds ratio, 8.14; 95% confidence interval, 1.02-14.47); shoulder dystocia (odds ratio, 7.88; 95% confidence interval, 1.07-13.99); vacuum delivery (odds ratio, 2.01; 95% confidence interval, 1.15-5.98); cesarean delivery (odds ratio, 1.86; 95% confidence interval, 1.12-3.79); and general anesthesia during cesarean delivery (odds ratio, 7.66; 95 % confidence interval, 3.11-9.36). According to machine learning analysis, the top 5 algorithms were XGBoost regression (area under the receiver operating characteristic curve of 99%), XGBoost classification (area under the receiver operating characteristic curve of 98%), LightGBM (area under the receiver operating characteristic curve of 94%), random forest regression (area under the receiver operating characteristic curve of 86%), and linear regression (area under the receiver operating characteristic curve of 78%). However, after considering all performance parameters, the XGBoost classification was found to be the best model to predict postpartum hemorrhage. The importance of the variables in the linear regression model, similar to traditional analysis methods, revealed that macrosomia, general anesthesia, anemia, shoulder dystocia, and abnormal placentation were considered to be weighted factors, whereas XGBoost classification considered living residency, parity, cesarean delivery, education, and induced labor to be weighted factors.

CONCLUSION

Risk factors for postpartum hemorrhage can be identified using traditional statistical analysis and a machine learning model. Machine learning models were a credible approach for improving postpartum hemorrhage prediction with high accuracy. More research should be conducted to analyze appropriate variables and prepare big data to determine the best model.

Route of postpartum oxytocin administration and maternal hemoglobin decline - A randomized controlled trial

OBJECTIVE

Oxytocin uterotonic agents are routinely administered during the third stage of labor, however, the administration route is varying, intravenously or intramuscularly. We aimed to compare the effect of different regimens of postpartum oxytocin administration on hemoglobin (Hb) and hematocrit (Hct) decline.

METHODS

A randomized, 3-arm study of women who delivered vaginally at term in a single tertiary medical center was conducted. Immediately following the delivery of the fetus women randomly received one of 3 oxytocin regimens: 1) intramuscular 10units (IM group); 2) intravenous 10units in 100 ml 0.9%NaCl solution over 10-15 min (IV group); or 3) combined IV + IM regimens (IV + IM group). Primary outcome was defined as the level of Hb decline between prepartum and postpartum measurements.

RESULTS

Overall, 210 women (70 in each group) were randomized, with 171 included in the final analysis (IM group-61, IV group-57, IV + IM group-53). There was no significant difference between the groups regarding maternal age, pre-pregnancy body-mass-index (BMI), parity, operative vaginal deliveries rate, the rate of episiotomy or perineal tears or neonatal birthweight. Mean prepartum Hb and Hct level were 12.3 ± 1.1 g/dl and 36.9 ± 2.7%, respectively, with no significant difference between the groups. Mean postpartum HB and Hct decline was 1.3 ± 0.8 g/dl and 3.7 ± 2.3%, respectively, with no difference between the groups. In multivariable analysis after adjusting for parity, pre-pregnancy BMI, labor induction, episiotomy or perineal tears and neonatal birthweight, oxytocin regimen was not associated with any difference in hematological measurements.

CONCLUSION

Postpartum Hb and Hct decline was usually minor following vaginal deliveries, and was not affected by postpartum oxytocin regimen.

Vacuum-assisted vaginal deliveries among parturients with congenital uterine anomalies; risk factors and outcomes

OBJECTIVE

To evaluate the maternal and neonatal outcomes associated with vacuum-assisted vaginal delivery (VAVD) in a subset of parturients with congenital uterine anomalies.

STUDY DESIGN

A retrospective database study was conducted at a single tertiary center between 2005 and 2019. Parturients with known congenital uterine anomalies who had vaginal deliveries were enrolled, whereas parturients with failed VAVD, didelphic uterus, and delivery after intrauterine fetal death were excluded. Various maternal and neonatal outcomes were compared between parturients who achieved spontaneous vaginal delivery (SVD) and those who delivered via VAVD. The maternal composite outcome was calculated for each group and included one or more of the following: post-partum hemorrhage, hemoglobin drop ≥ 4 gr/dL, blood transfusions, retained placental products, and obstetric anal sphincter injuries. Univariate analysis was performed followed by multivariate logistic regression analysis controlling for potential confounders. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

After the application of the exclusion criteria, 332 parturients were found eligible. Of those, 289 (87%) had SVD and 43 (13%) had VAVD. VAVD was more common among primiparous parturients and epidural analgesia users. Parturients with VAVD had higher rates of third-degree perineal tear, postpartum hemorrhage, and blood transfusions. The maternal composite outcome was significantly more prevalent in the VAVD group (44.2% vs. 20.8%, p < 0.01). After controlling for potential confounders, the maternal composite outcome was found to be independently associated with VAVD (aOR 2.3, 95% CI 1.10-4.60). The neonatal results were overall comparable, except for scalp trauma and Erb's palsy/clavicular fracture, which were more prevalent in the VAVD group.

CONCLUSION

In a special population of parturients with congenital uterine anomalies, VAVD was found to be associated with significantly higher rates of adverse maternal outcomes and perinatal birth trauma. These findings should be presented to parturients during consultations about modes of delivery.

The role of mediolateral episiotomy during vacuum-assisted vaginal delivery with soft cup devices

PURPOSE

This study evaluated whether episiotomy during vacuum-assisted delivery leads to fewer third- and fourth-degree tears.

METHODS

This was a retrospective cohort study of all nulliparas who underwent a singleton, soft cup, vacuum-assisted vaginal delivery in one institution, from January 2014 to August 2019. Failed vacuum deliveries were excluded. Based on power analysis calculation, a sample size of 500 women in each group was sufficient to detect an advantage of episiotomy, if present. Primary outcome was third- or fourth-degree perineal tear. Secondary outcomes were other maternal complications, and low neonatal cord pH and Apgar scores. Outcomes were compared between women with and without episiotomy.

RESULTS

During the study period, 2370 nulliparas had a vacuum-assisted vaginal delivery using soft vacuum cup and met the study inclusion criteria. Episiotomy was performed in 1868 (79%) women, and 502 (21%) delivered without episiotomy. Background characteristics were similar in both groups. There were no significant differences in the rates of third and fourth grade perineal lacerations between the two groups. Episiotomy was associated with higher rate of postpartum hemorrhage (p < 0.01) CONCLUSIONS: Using selective episiotomy for patients delivering vaginally with the assistance of soft cap vacuum does not increase third- or fourth-degree perineal tears.

Vacuum extraction in twin deliveries-maternal and neonatal consequences: a retrospective cohort study

PURPOSE

To establish the frequency of vacuum extraction among parturients with twin pregnancies, identify the risk factors and perinatal outcomes.

METHODS

A retrospective cohort database study was conducted between 2005-2018. Twin fetuses with vertex presentation >34 weeks gestation who achieved vaginal delivery were included. Outcomes were compared between neonates who were delivered by vacuum extraction and neonates delivered by spontaneous vaginal delivery (aORs; [95% CI]).

RESULTS

A total of 1751 neonates of 905 parturients with twin pregnancies met inclusion criteria, of which 163 (18%) parturients had vacuum extraction and 225 (12.8%) neonates were delivered by vacuum extraction. The most significant risk factors for vacuum extraction were primiparity (6.79 [4.77-9.66]), previous cesarean delivery (5.59 [3.13-9.97]), and epidural analgesia (4.34 [1.83-10.31]). Vacuum extractions were associated with a spectrum of adverse maternal outcomes (2.60 [1.61-4.19]), particularly postpartum hemorrhage and its associated morbidities. From the neonatal aspect, vacuum extraction deliveries were associated with a composite of birth trauma injuries (21.81 [6.43-73.91]).

CONCLUSION

Vacuum extractions among twin pregnancies were found to be associated with significantly higher rates of postpartum hemorrhage, blood transfusion, and perinatal birth trauma. These findings should be presented to women when counseling on mode of delivery and considered individually against cesarean delivery disadvantages.

Induction of labor and postpartum blood loss

BACKGROUND

To analyze blood loss after delivery in women with induction of labor compared to women with spontaneous onset of labor.

METHODS

In this secondary analysis of a prospective cohort study investigating postpartum hemorrhage, 965 deliveries were analyzed including 380 women with induction of labor (39%) between 2015 and 2016. Primary outcome parameters were rate of postpartum hemorrhage, estimated blood loss and post-partum decrease in hemoglobin.

RESULTS

Rates of postpartum hemorrhage and estimated blood loss were not significantly different in women with induction of labor. Women with induction of labor had a significantly reduced decrease in hemoglobin after delivery. In the multivariate linear regression analysis, induction of labor remained associated with reduced decrease in hemoglobin. Secondary maternal and neonatal outcomes were unaffected.

CONCLUSIONS

Induction of labor is not associated with increased blood loss after delivery and should not be regarded as a risk factor for postpartum hemorrhage.

Kiwi omnicup handheld versus Mityvac M-style conventional vacuum system: a retrospective observational study

INTRODUCTION

To improve the choice of vacuum-assisted delivery (VAD) system, we compared the outcomes of Kiwi handheld system and Mityvac M-style conventional system (both use disposable plastic cups).

MATERIALS AND METHODS

Retrospective observational study with data collection from electronic medical records. The study was conducted at a tertiary medical center, with approximately 7000 deliveries annually. Categorical and continuous variables were analyzed using chi-square test and t-test, respectively. p value < .05 was considered significant. The main outcomes assessed were the overall failure rate of each system, failure rates for occipito-anterior (OA) versus occipito-transverse/occipito-anterior (OT/OP) positions, +1 versus +2 fetal stations, and early maternal/neonatal outcomes.

RESULTS

During a 10-month period, there were 507 (8.4%) attempted VADs, 36 failed (7.1%), and eight (1.5%) converted to cesarean section. Of these, 364 were Kiwi-assisted and 143 Mityvac-assisted. Background characteristics were similar. The handheld system had more failures overall (9.6 versus 0.7%), at OA (7.6 versus 0.9%), and non-OA positions (17.3% versus none), at +1 (13.25 versus 0.96%) and at +2/3 stations (6.1% versus none), than the conventional system did, respectively. There was a higher rate of early post-partum hemorrhage (15.3 versus 7.4%) in the conventional group. Both systems had similar rates of third/fourth degree perineal tears, shoulder dystocia and adverse neonatal outcomes.

CONCLUSIONS

Our results suggest more failures with Kiwi compared to Mityvac, overall and at any fetal position/station, without a significant difference in adverse outcome profile.