Factors predictive of failed operative vaginal delivery

Vacuum-assisted delivery outcomes: is advanced maternal age a factor?

PURPOSE

This study evaluated age-related maternal outcomes of vacuum-assisted vaginal deliveries (VAD).

METHODS

This retrospective cohort study included all nulliparous women with singleton VAD in one academic institution. Study group parturients were maternal age ≥ 35 years and controls < 35. Power analysis revealed that 225 women/group would be sufficient to detect a difference in the rate of third- and fourth-degree perineal tears (primary maternal outcome) and umbilical cord pH < 7.15 (primary neonatal outcome). Secondary outcomes were maternal blood loss, Apgar scores, cup detachment, and subgaleal hematoma. Outcomes were compared between groups.

RESULTS

From 2014 to 2019, 13,967 nulliparas delivered at our institution. Overall, 8810 (63.1%) underwent normal vaginal delivery, 2432 (17.4%) instrumental, and 2725 (19.5%) cesarean. Among 11,242 vaginal deliveries, 10,116 (90%) involved women < 35, including 2067 (20.5%) successful VAD vs. 1126 (10%) women ≥ 35 years with 348 (30.9%) successful VAD (p < 0.001). Rates of third- and fourth-degree perineal lacerations were 6 (1.7%) with advanced maternal age and 57 (2.8%) among controls (p = 0.259). Cord pH < 7.15 was similar: 23 (6.6%) study group and 156 (7.5%) controls (p = 0.739).

CONCLUSION

Advanced maternal age and VAD are not associated with higher risk for adverse outcomes. Older, nulliparous women are more likely to undergo vacuum delivery than younger parturients.

Association of maternal body mass index with success and outcomes of attempted operative vaginal delivery

BACKGROUND

Increasing maternal body mass index is associated with increased morbidity at cesarean delivery in a dose-dependent manner. In some clinical scenarios, operative vaginal delivery is a strategy to prevent the morbidity associated with second-stage cesarean delivery, but the relationship between maternal body mass index and outcomes of attempted operative vaginal delivery is not well characterized.

OBJECTIVE

This study aimed to assess whether the success of and adverse outcomes after attempted operative vaginal delivery are associated with maternal body mass index at delivery among nulliparous individuals.

STUDY DESIGN

This was a secondary analysis from the prospective cohort Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be study. This analysis included cephalic live-born nonanomalous singleton pregnancies ≥34 weeks at delivery with an attempted operative vaginal delivery (either forceps or vacuum). The primary exposure was maternal body mass index at delivery (≥30 vs <30 kg/m2 [referent]). The primary outcome was an unsuccessful operative vaginal delivery attempt, defined as a cesarean delivery after an attempted operative vaginal delivery. The secondary outcomes included maternal and neonatal adverse outcomes. Multivariable logistic regression was used, and statistical interaction between operative instrument type (vacuum vs forceps) and body mass index was assessed.

RESULTS

Of 10,038 assessed individuals, 791 (7.9%) had an attempted operative vaginal delivery and were included in this analysis. Of note, 325 individuals (41%) had a body mass index ≥30 kg/m2 at delivery. Overall, 42 of 791 participants (5%) experienced an unsuccessful operative vaginal delivery. Individuals with a body mass index ≥30 kg/m2 at delivery were more than twice as likely to have an unsuccessful operative vaginal delivery than those with a body mass index <30 kg/m2 (8.0% vs 3.4%; adjusted odds ratio, 2.23; 95% confidence interval, 1.16-4.28; P=.005). Composite maternal morbidity and composite neonatal morbidity did not vary by body mass index group. There was no evidence of interaction or effect modification by operative instrument type for the rate of unsuccessful operative vaginal delivery attempt, composite maternal morbidity, or composite neonatal morbidity.

CONCLUSION

Among nulliparous individuals who underwent an attempted operative vaginal delivery, those with a body mass index ≥30 kg/m2 at delivery were more likely to have an unsuccessful operative vaginal delivery attempt than those with a body mass index <30 kg/m2. There was no difference in composite maternal or neonatal morbidity after attempted operative vaginal delivery by body mass index category.

Clinical and Physician Factors Associated With Failed Operative Vaginal Delivery

OBJECTIVE

To examine clinical and physician factors associated with failed operative vaginal delivery among individuals with nulliparous, term, singleton, vertex (NTSV) births.

METHODS

This was a retrospective cohort study of individuals with NTSV live births with an attempted operative vaginal delivery by a physician between 2016 and 2020 in California. The primary outcome was cesarean birth after failed operative vaginal delivery, identified using linked diagnosis codes, birth certificates, and physician licensing board data stratified by device type (vacuum or forceps). Clinical and physician-level exposures were selected a priori, defined using validated indices, and compared between successful and failed operative vaginal delivery attempts. Physician experience with operative vaginal delivery was estimated by calculating the number of operative vaginal delivery attempts made per physician during the study period. Multivariable mixed effects Poisson regression models with robust standard errors were used to estimate risk ratios of failed operative vaginal delivery for each exposure, adjusted for potential confounders.

RESULTS

Of 47,973 eligible operative vaginal delivery attempts, 93.2% used vacuum and 6.8% used forceps. Of all operative vaginal delivery attempts, 1,820 (3.8%) failed; the success rate was 97.3% for vacuum attempts and 82.4% for forceps attempts. Failed operative vaginal deliveries were more likely with older patient age, higher body mass index, obstructed labor, and neonatal birth weight more than 4,000 g. Between 2016 and 2020, physicians who attempted more operative vaginal deliveries were less likely to fail. When vacuum attempts were successful, physicians who conducted them had a median of 45 vacuum attempts during the study period, compared with 27 attempts when vacuum attempts were unsuccessful (adjusted risk ratio [aRR] 0.95, 95% CI 0.93-0.96). When forceps attempts were successful, physicians who conducted them had a median of 19 forceps attempts, compared with 11 attempts when forceps attempts were unsuccessful (aRR 0.76, 95% CI 0.64-0.91).

CONCLUSION

In this large, contemporary cohort with NTSV births, several clinical factors were associated with operative vaginal delivery failure. Physician experience was associated with operative vaginal delivery success, more notably for forceps attempts. These results may provide guidance for physician training in maintenance of operative vaginal delivery skills.

A retrospective cohort study of the characteristics of unsuccessful operative vaginal deliveries

INTRODUCTION

Unsuccessful operative vaginal delivery (OVD) is associated with high rates of materno-fetal morbidity. We aimed to examine institutional rates of unsuccessful OVDs (uOVD) and compare them with successful OVD (sOVD) in order to identify factors to aid patient selection and education.

METHODS

A 6-month retrospective cohort study was performed on all unsuccessful and successful OVDs in a tertiary level maternity hospital in the Republic of Ireland. Maternal demographics and obstetric factors were assessed to evaluate potential underlying risk factors for unsuccessful operative vaginal delivery versus successful vaginal delivery.

RESULTS

There were 4,191 births during the study period with an OVD rate of 14.2% (n = 595) with 28 (4.7% of OVDs) being unsuccessful. Unsuccessful OVD were predominately nulliparous (25; 89.2%) with a mean maternal age of 30.1 years (range 20-42), with more than half (n = 15, 53.5%) being induced. The most common indication for induction was prolonged rupture of membranes (PROM) (n = 7, 25%) which was significantly different from the successful OVD group. A senior obstetrician was significantly more likely to be the primary operator in uOVD when compared to sOVD. (82.1 % V 54.1% p < 0.01). The majority of unsuccessful OVD were vacuum deliveries (n = 17; 60.7%), with a significantly higher mean birthweight when compared to successful OVD (3.695 kg V 3.483 kg; p < 0.01). Following an unsuccessful OVD, women were more likely to have a postpartum haemorrhage (64.2 % V 31.5% p < 0.01) and their infant was more likely to require admission to the neonatal intensive care unit (NICU) (32.1 % V 5.8% p < 0.01) when compared with successful OVD.

CONCLUSION

Risk factors for unsuccessful OVD were higher birth weight and induction of labour. There was a higher incidence of postpartum haemorrhage and NICU admission when compared with successful OVD.

Antepartum ultrasound prediction of failed vacuum-assisted operative delivery: a prospective cohort study

BACKGROUND

Failed vacuum-assisted delivery (VD) is associated with increased risk of maternal perineal trauma and neonatal morbidity. Knowledge of the risk factors related to failed VD is essential in the clinical decision-making.

OBJECTIVE

To elucidate the strength of association and the predictive accuracy of different ante-partum ultrasound parameters in predicting the risk of failed VD prior to the onset of Labor and to test the diagnostic performance of a multiparametric model including pregnancy and Labor characteristics, ante and intra-partum ultrasound in anticipating failed VD.

STUDY DESIGN

Prospective study of consecutive singleton pregnancies complicated by VD undergoing a dedicated ultrasound assessment at 36-38 weeks of gestation. Head circumference (HC), estimated fetal weight (EFW) and subpubic angle and (SPA) were recorded before the onset of Labor. At the time of the VD, occiput position, head perineum distance (HPD) and angle of progression (AOP) were also recorded. Multivariate logistic regression and area under the curve (AUC) analyses were used to explore the strength of association and test the diagnostic accuracy of different maternal, Labor and ultrasound characteristics in predicting g failed VD.

RESULTS

Four hundred eight pregnancies with successful and 26 with failed VD were included in the analysis. Fetuses experiencing failed VD had a larger HC (1.21 versus 1.07 MoM; p = .0001), a higher EFW z-value (0.56 versus 0.33 z values; p = .002) and a narrower SPA (114 versus 122 p = .0001) compared to those having a successful VD. At multivariable logistic regression analysis, maternal height (aOR 0.89 95% CI 0.76-0.98), nulliparity (aOR: 1.14 95% CI 1.06-1.36), HC MoM (aOR: 1.24 95% CI 1.13-1.55) and SPA angle (aOR: 0.82 95% CI 0.67-0.95), but not EFW (p = .08) were independently associated with failed VD. When intrapartum ultrasound variables were added to the multivariate model, fetal occipital position (aOR: 1.45 95th CI 1.11-1.99) and HPD (aOR: 0.77 95th CI 0.44-0.96) were independently associated with failed VD. A multiparametric model integrating pregnancy and Labor characteristics and ante-partum ultrasound variables had an AUC of 0.837 (95% CI 0.797-0.876) for the prediction of failed VE. The addition of intra-partum ultrasound variables to the prediction model, improved the accuracy for failed VD provided by maternal and antepartum ultrasound characteristics with an AUC of 0.913 (0.888-0.937).

CONCLUSION

Antepartum prediction of failed VD is feasible. HC, SPA but not EFW are independently associated and predictive of failed VD. Adding these variables to a multiparametric model including maternal and intrapartum ultrasound parameters improves the diagnostic accuracy for failed VD.

SMFM Special Statement: Operative vaginal delivery: checklists for performance and documentation

The frequency of operative vaginal delivery has been declining, even though it can be an attractive alternative to cesarean delivery in selected cases. Performance of operative vaginal delivery required consideration of many indications, contraindications, and prerequisites. Optimal documentation of operative vaginal delivery requires the recording of several specific elements that are unique to forceps or vacuum delivery. A cognitive aid such as a checklist is well suited to this situation in which there are numerous elements to consider, a low frequency of performance, and teams with variable expertise. We propose 2 checklists to help ensure that all relevant elements are considered for every operative vaginal delivery: (1) a checklist for preparation and performance of the procedure and (2) a checklist for documentation. We suggest practical tips to help facilities adapt these checklists to their own circumstances and implement them on their units.

Successful versus unsuccessful instrumental deliveries-Predictors and obstetric outcomes

OBJECTIVE

The purpose of this study was to examine instrumental births in a multi-ethnic population to assess the factors associated with success and failure in instrumental births.

STUDY DESIGN

This was a large retrospective study of 7954 women that underwent either a successful or an unsuccessful instrumental delivery in a single centre over a 10 year period.

RESULTS

Logistic regression analysis showed that women with a BMI of more than 30, attempted Forceps delivery, having a prolonged second stage, Macrosomia (birth weight more than 4 kg) and a senior obstetrician performing the procedure increase the risk of a failed instrumental delivery. While age, ethnicity, type of anaesthesia, use of oxytocin or induction of labour did not provide a significant outcome. Results also showed that patients are likely to bleed more and neonates need admission in failed instrumental deliveries when compared to successful attempts.

CONCLUSION

This is one of a very few studies comparing a large cohort of successful instrumental births with unsuccessful attempts at an instrumental birth. The rate of failure has been difficult to reduce, and the analysis shows that many of the factors associated with failure are not modifiable in labour. We should consider studies with use of ultrasound assessment before application or consideration of instruments to facilitate birth. This will allow us to objectively come up with an algorithm to predict success or failure and consider if it is suitable to attempt an instrumental birth. Our data can be used to counsel women about the difficulty in predicting success and failure rate of instrumental births.

Failed Vacuum and the Long-term Hematologic Morbidity of the Offspring

OBJECTIVE

We aimed to investigate the effect of failed vacuum delivery leading to an emergency cesarean delivery on the long-term pediatric hematologic morbidity of the offspring.

STUDY DESIGN

In this population-based cohort study, the risk of long-term hematologic morbidity (up to the age of 18 y) was evaluated in children born following successful vacuum vaginal delivery, as compared with that of children born following a failed procedure leading to an emergent cesarean delivery. Multiple pregnancies and fetuses with congenital malformations were excluded. A Kaplan-Meier survival curve was constructed to compare cumulative pediatric hematologic morbidity, and a Cox proportional hazards model was used to control for confounders.

RESULTS

A total of 7978 neonates met the inclusion criteria. Vacuum delivery was successful in 7733 cases (96.9%), whereas it failed in 245 cases (3.1%). Total hematologic morbidity of the offspring up to 18 years of age was comparable between the groups (1.6% vs. 0.8%, P=0.8). The Kaplan-Meier survival curve showed no difference in the cumulative incidence of total hematologic morbidity (log rank, P=0.22). In the Cox regression model, failed vacuum delivery was not independently associated with long-term hematologic morbidity, as compared with a successful procedure, while adjusting for multiple confounders (adjusted hazards ratio [HR], 1.8; 95% confidence interval, 0.7-5.0; P=0.25).

CONCLUSIONS

Failed vacuum delivery does not seem to be associated with an increased risk for pediatric hematologic morbidity of the offspring up to 18 years of age.

Predictors for failure of vacuum-assisted vaginal delivery: a case-control study

OBJECTIVE

To identify potential predictors for failed vacuum-assisted delivery.

STUDY DESIGN

Retrospective case-control study conducted in two perinatal centers in the Netherlands. Cases were women who underwent a failed vacuum-assisted delivery between 1997 and 2011. A failed vacuum extraction was defined as a delivery that was started as vacuum extraction but was converted to a cesarean section because of failure to progress. As controls we studied two successful vacuum extractions that were performed before the failed one. We used multivariable logistic regression to assess the risk for failed vacuum extraction.

RESULTS

Between 1997 and 2011, 6734 trials of vacuum extraction were performed of which 309 failed (4.6%). These 309 cases were compared to the data of 618 women who underwent a successful vacuum extraction. Predictors for failed vacuum-assisted vaginal delivery were increasing gestational age (OR 1.2 per week), maternal height (OR 0.97 per cm), previous vaginal birth as compared to nulliparae (OR 0.32), estimated fetal weight ≥3750g as compared to <3250g (OR 5.7), epidural analgesia (OR 3.0), augmentation (OR 1.4), failure to progress as indication for trial of vacuum delivery (OR 1.7), station of descent of the fetal head (OR 0.31 per station more descended), and occiput posterior position (OR 2.6). The area under the receiver-operating characteristic curve of a prediction model integrating these indicators was 0.83.

CONCLUSION

Failed vacuum extraction can be predicted accurately using both ante- and intrapartum characteristics. There is a strong need for prospective studies on the subject.

Factors influencing the likelihood of instrumental delivery success

OBJECTIVE

To evaluate risk factors for unsuccessful instrumental delivery when variability between individual obstetricians is taken into account.

METHODS

We conducted a retrospective cohort study of attempted instrumental deliveries over a 5-year period (2008-2012 inclusive) in a tertiary United Kingdom center. To account for interobstetrician variability, we matched unsuccessful deliveries (case group) with successful deliveries (control group) by the same operators. Multivariate logistic regression was used to compare successful and unsuccessful instrumental deliveries.

RESULTS

Three thousand seven hundred ninety-eight instrumental deliveries of vertex-presenting, single, term newborns were attempted, of which 246 were unsuccessful (6.5%). Increased birth weight (odds ratio [OR] 1.11; P<.001), second-stage labor duration (OR 1.01; P<.001), rotational delivery (OR 1.52; P<.05), and use of ventouse compared with forceps (OR 1.33; P<.05) were associated with unsuccessful outcome. When interobstetrician variability was controlled for, instrument selection and decision to rotate were no longer associated with instrumental delivery success. More senior obstetricians had higher rates of unsuccessful deliveries (12% compared with 5%; P<.05) but were used to undertake more complicated cases. Cesarean delivery during the second stage of labor without previous attempt at instrumental delivery was associated with higher birth weight (OR 1.07; P<.001), increased maternal age (OR 1.03; P<.01), and epidural analgesia (OR 1.46; P<.001).

CONCLUSION

Results suggest that birth weight and head position are the most important factors in successful instrumental delivery, whereas the influence of instrument selection and rotational delivery appear to be operator-dependent. Risk factors for lack of instrumental delivery success are distinct from risk factors for requiring instrumental delivery, and these should not be conflated in clinical practice.

[Failure of vacuum extractions: risk factors, maternal and fetal issues]

OBJECTIVES

Determine cases which are at risk of vacuum extraction failure as well as maternal and foetal issues depending on the delivery outcome.

MATERIAL AND METHODS

It was a retrospective study comparing 147 vacuum failures, from January 2002 to December 2010, with a control group randomly composed of 526 successful vacuum extractions. The outcomes were high risk situations of vacuum failure, maternal and neonatal morbidity depending on the delivery method (caesarean section or other instrumental extraction).

RESULTS

The global vacuum failure rate was 3.3 %. During labour, we identified several situations at risk of vacuum extraction failure: cephalhematomas prior to extraction (P<0.001), deflexion attitude (P<0.001), posterior variety (P<0.001), entering above the inlet strait (P<0.001), occiput posterior delivery (P<0.001), fœtal weight greater than 3500g (P=0.023). Neonatals consequency were more Apgar score below 7 at five minutes life (P=0.007), fœtal acidosis (pH<7,20) (P=0.032), neonatal resuscitation (P<0.001), and craniofacial damages (P<0.001).

CONCLUSION

Many dystocic situations occurring during labour require intense care when practicing vacuum extraction since they more frequently result in failure. In case of vacuum extraction failure, immediate adaptation to extra-uterine life seems to be more difficult for new-born babies.

Prevention of the first cesarean delivery: the role of operative vaginal delivery

While the cesarean delivery (CD) rates have increased worldwide, operative vaginal delivery (OVD) rates continue to decline, with the United States having some of the lower rates amongst developed countries. It is clear that the use of forceps or vacuum can safely assist in accomplishing a vaginal delivery and prevent a cesarean during the IInd stage of labor performed for a variety of maternal or fetal indications. In the absence of randomized trials between OVD's and immediate CD's for anticipated difficult births the question of the balance of risks between the two interventions remains unanswered. Properly performed OVD's are associated with lower maternal morbidity compared with cesarean, without an increase in significant neonatal morbidity. In order to reverse the current trends and for these skills to continue active training in OVD's is clearly needed during and after residency. The availability of clinicians with expertise in OVD's should aid in decreasing the rates of CD and the training of newer generations of practitioners. The professional endorsement of OVD's is also fundamental not only to frame the practice for physicians but to promote and improve the general acceptance of assisted deliveries and facilitate the societal discourse to reduce CD rates.

A clinical prediction model to assess the risk of operative delivery

OBJECTIVE

To predict instrumental vaginal delivery or caesarean section for suspected fetal distress or failure to progress.

DESIGN

Secondary analysis of a randomised trial.

SETTING

Three academic and six non-academic teaching hospitals in the Netherlands.

POPULATION

5667 labouring women with a singleton term pregnancy in cephalic presentation.

METHODS

We developed multinomial prediction models to assess the risk of operative delivery using both antepartum (model 1) and antepartum plus intrapartum characteristics (model 2). The models were validated by bootstrapping techniques and adjusted for overfitting. Predictive performance was assessed by calibration and discrimination (area under the receiver operating characteristic), and easy-to-use nomograms were developed.

MAIN OUTCOME MEASURES

Incidence of instrumental vaginal delivery or caesarean section for fetal distress or failure to progress with respect to a spontaneous vaginal delivery (reference).

RESULTS

  375 (6.6%) and 212 (3.6%) women had an instrumental vaginal delivery or caesarean section due to fetal distress, and 433 (7.6%) and 571 (10.1%) due to failure to progress, respectively. Predictors were age, parity, previous caesarean section, diabetes, gestational age, gender, estimated birthweight (model 1) and induction of labour, oxytocin augmentation, intrapartum fever, prolonged rupture of membranes, meconium stained amniotic fluid, epidural anaesthesia, and use of ST-analysis (model 2). Both models showed excellent calibration and the receiver operating characteristics areas were 0.70-0.78 and 0.73-0.81, respectively.

CONCLUSION

  In Dutch women with a singleton term pregnancy in cephalic presentation, antepartum and intrapartum characteristics can assist in the prediction of the need for an instrumental vaginal delivery or caesarean section for fetal distress or failure to progress.

Operative vaginal deliveries: practical aspects

Forceps, vacuum, and cesarean sections are relatively recent additions to the obstetrician's armamentarium. The art of modern obstetrics is one that mandates from obstetricians the attentive vigilance of the development of natural processes and an active intervention when such processes fall outside normally accepted standards. What constitutes the "normal process" and the "accepted standard" is subject to discussion, and international variations in obstetric practice are in part the reflection of such controversies. This article presents a practical approach to the contemporary issue of instrumental deliveries, outlining supporting evidence (when available) and the most current position of professional colleges in obstetrics and gynecology.

Maternal outcome of gestational diabetes mellitus

OBJECTIVE

To estimate maternal outcome of treated or untreated gestational diabetes mellitus (GDM).

METHODS

French and English publications were searched using PubMed and the Cochrane library.

RESULTS

The diagnosis of GDM includes a high risk population for preeclampsia and Caesarean sections (EL3). The risks are positively correlated with the level of hyperglycaemia in a linear way (EL2). Intensive treatment of mild GDM compared with routine care reduces the risk of pregnancy-induced hypertension (preeclampsia, gestational hypertension). Moreover, it does not increase the risk of operative vaginal delivery, Caesarean section and postpartum haemorrhage (EL1). Being overweight, obesity and maternal hyperglycaemia are independent risk factors for preeclampsia (EL2). Their association with GDM increases the risk of preeclampsia and Caesarean section compared to diabetic women with a normal body mass index (EL3). The association of several risk factors (such as advanced maternal age, pre-existing chronic hypertension, pre-existing nephropathy, obesity, suboptimal glycaemic control) increases the risk of preeclampsia. In that case, the classic follow-up (blood pressure measurement, proteinuria) should be more frequent than monthly (professional consensus). The risk of Caesarean section is increased by macrosomia, whether suspected prenatally or not, but this increased risk remains whatever the birth weight (EL3). Diagnosis and treatment of GDM do not reduce the risk of severe perineal lesions, operative vaginal delivery and postpartum haemorrhage (EL2). Some psychological symptoms, such as anxiety and alteration of self-perception, can occur upon diagnosis of GDM (EL3). The treatment of GDM appears to reduce the risk of postpartum depression symptoms (EL2).

CONCLUSION

Most of the information published on GDM covers the risks of preeclampsia and Caesarean section; intensive care of GDM reduces these risks. Pregnancy care should be adjusted to the risk factors.

Predictors of failed operative vaginal delivery: a single-center experience

OBJECTIVE

The purpose of this study was to identify factors that predict operative vaginal delivery.

STUDY DESIGN

A retrospective cohort study was conducted that included all women who underwent a trial of operative vaginal delivery between 1993 and 2006 at a major tertiary center.

RESULTS

Operative vaginal delivery was attempted in 5120 of 83,351 deliveries (6.1%): 4299 vacuum extractions (84.0%) and 821 forceps deliveries (16.0%). Failures occurred in 8.6% of trials, more often with vacuum extraction (10.0% vs 1.3%; P < .001). Most vacuum extraction failures (72.6%) were followed by a trial of forceps delivery, which failed in 3.5% of cases. On multivariate logistic regression analysis, the use of forceps (vs vacuum; odds ratio [OR], 0.4; 95%CI, 0.2-0.7) and administration of analgesia (epidural: OR, 0.4 [95% CI, 0.2-0.7]; intravenous opiates: OR, 0.2 [95%CI, 0.1-0.6]) were associated with a lower risk of failure, persistent occiput posterior position (OR, 2.2; 95% CI, 1.4-3.5) and birthweight >4000 g (OR, 2.8; 95% CI, 1.6-4.9), with a higher risk.

CONCLUSION

Fetal weight and head position should be evaluated carefully before operative vaginal delivery, and the use of analgesia should be encouraged.

Cervical length assessment in women with idiopathic polyhydramnios

OBJECTIVE

The aims of the study were to determine cervical length among patients with polyhydramnios and to assess the relationship between the severity of polyhydramnios, cervical length and gestational age at delivery.

PATIENTS AND METHODS

A prospective study was designed including 92 consecutive singleton pregnancies with polyhydramnios between 24 and 40 weeks' gestation. Cervical length was measured using transvaginal sonography. Polyhydramnios was defined when amniotic fluid index (AFI) was equal to or greater than 20 cm. A single sonologist performed all the examinations of the cervical length and the AFI.

RESULTS

The median cervical length and AFI were 37.5 (range, 7-52) mm and 28.8 (range, 20-43) cm, respectively. A significant gradual shortening of the cervical length was observed with advancing gestational age (P=0.027). No significant association was found between AFI and cervical length (P=0.24). A cut-off of 15 mm (n=5) was associated with a significantly lower gestational age at delivery (30+/-2.6 weeks vs. 37.2+/-4.2 weeks, respectively, P<0.001).

CONCLUSIONS

Women with polyhydramnios have a gradual shortening of cervical length with advancing gestational age. However, this finding is not related to the severity of polyhydramnios.

The reporting of pre-existing maternal medical conditions and complications of pregnancy on birth certificates and in hospital discharge data

OBJECTIVE

The purpose of this study was to determine the accuracy of live-birth certificates and hospital discharge data that reported of pre-existing maternal medical conditions and complications of pregnancy.

STUDY DESIGN

We conducted a population-based validation study in 19 non-federal short-stay hospitals in Washington state with a stratified random sample of 4541 women who had live births between January 1, 2000, and December 31, 2000. True- and false-positive fractions were calculated.

RESULTS

Birth certificate and hospital discharge data combined had substantially higher true-positive fractions than did birth certificate data alone for cardiac disease (54% vs 29%), acute or chronic lung disease (24% vs 10%), gestational diabetes mellitus (93% vs 64%), established diabetes mellitus (97% vs 52%), active genital herpes (77% vs 38%), chronic hypertension (70% vs 47%), pregnancy-induced hypertension (74% vs 49%), renal disease (13% vs 2%), and placenta previa (70% vs 33%). For the 2 medical risk factors that are available only on birth certificates, true-positive fractions were 37% for established genital herpes and 68% for being seropositive for hepatitis B surface antigen.

CONCLUSION

In Washington, most medical conditions and complications of pregnancy that affect mothers are substantially underreported on birth certificates, but hospital discharge data are accurate in the reporting of gestational and established diabetes mellitus and placenta previa. Together, birth certificate and hospital discharge data are much superior to birth certificates alone in the reporting of gestational diabetes mellitus, active genital herpes, and chronic hypertension.