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PubMed2002

Shoulder dystocia and brachial plexus injury: a population-based study.

The objective of this work was to identify and evaluate risk factors for shoulder dystocia and for brachial plexus injury in a population-based study. In all, 1,397 parturients with shoulder dystocia occurring in Sweden between 1987 and 1996 were identified among 1,076,545 deliveries using information stored in the Medical Birth Registry (MBR) of the National Board of Health and Welfare, Stockholm. Information is missing for about 1.0% of singleton deliveries in the MBR. Validation of the diagnosis 'shoulder dystocia' in the MBR was performed using data of 4 of 63 delivery units and was confirmed in 96.5% of the original medical records. A total of 368 infants had brachial plexus injury (26.3%). However, a considerable variation in the rate of recorded shoulder dystocia was evident when comparing the 63 delivery units throughout Sweden. Overall, the incidence was 1.3 per 1,000 deliveries. A close association was found between birth weight and shoulder dystocia, with an odds ratio (OR) over 30 for a birth weight > or = 5,000 g. In the presence of maternal diabetes mellitus or gestational diabetes, the OR for shoulder dystocia was significantly increased in newborns weighing > or = 4,000 g. The overall perinatal mortality because of shoulder dystocia was 1.2%. This was increased to 6.4% if the mother had diabetes mellitus. About 25% of all infants suffered a brachial plexus injury. This potentially serious injury even occurred in connection with birth by cesarean section, and an OR for plexus injury over unity was seen in 7 of 9 weight groups; a significantly increased OR was seen for birth weights > or = 4,500 g. The birth weight is a strong risk factor for shoulder dystocia, as is diabetes mellitus. A considerable variation in the rate of shoulder dystocia was observed among the different delivery units, probably reflecting difficulties in definition. Brachial plexus injury is observed even after cesarean section, especially if the birth weight is > or = 4,500 g.

Birth Injuries↗
PubMed2002

[Dystocia: frequency and risk factors in seven areas in West Africa].

OBJECTIVES: 1) To measure the incidence of dystocia in six cites and one rural area in West Africa. 2) To identify risk factors of dystocia and analyze their interrelationships with the goal to potentially use them to identify high-risk pregnant women attending antenatal consultations. (3) To assess their usefulness as predictors of dystocia during pregnancy. METHODS: The MOMA study is a prospective population-based follow-up study of 20,326 pregnant women in West Africa. Due to the likely diagnostic and recall bias for home deliveries, risk factors for dystocia were analyzed only for deliveries in health facilities. A total of 16,318 deliveries were analyzed. RESULTS: The incidence of dystocia was 18.3% (95%CI: 17.7-18.9). Multivariate analysis using stepwise logistic regression disclosed the following significant risk factors: short stature, scarred uterus, nulliparity. Positive predictive values were very low for both univariate and multivariate analysis. CONCLUSION: The incidence of dystocia, which occurs mainly at delivery, is high in West Africa. Consequences are often dramatic, both for the fetus and the mother. None of the risk factors studied, even when used in combination, provided a good prediction of dystocia. All pregnant women should therefore be considered at risk of dystocia. Efforts should be made to detect dystocia during labor (partography) and to provide good-quality emergency obstetric care. Emergency obstetric care must be made available to all pregnant women. This goal can be achieved in most of the major West African cities. More facilities offering good-quality cesarean section must be made available.

Adolescent↗
PubMed1992

Patterns of stillbirth and dystocia in Ontario cow-calf herds.

The association between a number of individual animal and herd level factors and calving problems in beef cows and heifers were examined. Data were from the 1987 calving season for a subset of 123 herds which maintained individual-animal records, from a sample of 180 randomly selected Ontario cow-calf herds. The median herd dystocia rate was 5.8% and 24.4% of herds had no dystocias. The median herd stillbirth rate was 2.8%, and 33.3% of herds had no stillbirths. Dystocias and stillbirths were much more common in heifers than in cows. Separate statistical models of dystocia and stillbirth for cows and heifers were created. Dystocia in cows was associated with calf sex, previous calving assistance and large breed type and birth weight. Variations in 1987 cow herd dystocia rates were associated with calving season, location and density, and the herd dystocia rate in 1986. Dystocia in heifers was associated with large breed type and calf birth weight. Herd-level management practices associated with increased heifer dystocia rates included breeding heifers to calve earlier than cows and rearing heifers together with the cow herd. Stillbirths for both cows and heifers were associated with calving assistance, particularly hard assistance. Herd-level management and other factors were unassociated with stillbirths.

Animals↗
PubMed2006

Intrapartum interventions for preventing shoulder dystocia.

BACKGROUND: The early management of shoulder dystocia involves the administration of various manoeuvres which aim to relieve the dystocia by manipulating the fetal shoulders and increasing the functional size of the maternal pelvis. OBJECTIVES: To assess the effects of prophylactic manoeuvres in preventing shoulder dystocia. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 June 2006). SELECTION CRITERIA: Randomised controlled trials comparing the prophylactic implementation of manoeuvres and maternal positioning with routine or standard care. DATA COLLECTION AND ANALYSIS: Two review authors independently applied exclusion criteria, assessed trial quality and extracted data. MAIN RESULTS: Two trials were included; one comparing the McRobert's manoeuvre and suprapubic pressure with no prophylactic manoeuvres in 185 women likely to give birth to a large baby and one trial comparing the use of the McRobert's manoeuvre versus lithotomy positioning in 40 women. We decided not to pool the results of the two trials. One study reported fifteen cases of shoulder dystocia in the therapeutic (control) group compared to five in the prophylactic group (relative risk (RR) 0.44, 95% confidence interval (CI) 0.17 to 1.14) and the other study reported one episode of shoulder dystocia in both prophylactic and lithotomy groups. In the first study, there were significantly more caesarean sections in the prophylactic group and when these were included in the results, significantly fewer instances of shoulder dystocia were seen in the prophylactic group (RR 0.33, 95% CI 0.12 to 0.86). In this study, thirteen women in the control group required therapeutic manoeuvres after delivery of the fetal head compared to three in the treatment group (RR 0.31, 95% CI 0.09 to 1.02). One study reported no birth injuries or low Apgar scores recorded. In the other study, one infant in the control group had a brachial plexus injury (RR 0.44, 95% CI 0.02 to 10.61), and one infant had a five-minute Apgar score less than seven (RR 0.44, 95% CI 0.02 to 10.61). AUTHORS' CONCLUSIONS: There are no clear findings to support or refute the use of prophylactic manoeuvres to prevent shoulder dystocia, although one study showed an increased rate of caesareans in the prophylactic group. Both included studies failed to address important maternal outcomes such as maternal injury, psychological outcomes and satisfaction with birth. Due to the low incidence of shoulder dystocia, trials with larger sample sizes investigating the use of such manoeuvres are required.

Delivery, Obstetric↗
PubMed1996

Sonographic prediction of shoulder dystocia in infants of diabetic mothers.

OBJECTIVE: To determine if the difference between the abdominal diameter and biparietal diameter (AD-BPD difference), as measured by ultrasound examination, predicts shoulder dystocia in borderline macrosomic infants of diabetic mothers. METHODS: A retrospective study was performed of births occurring from January 1990 through June 1995. Eligibility requirements included diabetic pregnancy, ultrasound examination within 2 weeks of delivery, estimated fetal weight of 3800-4200 g, and vaginal delivery. The mean AD-BPD difference was compared in normal deliveries and those complicated by shoulder dystocia, using the Student t test and by multiple regression analysis. A receiver operating characteristic curve was generated to determine if an AD-BPD cutoff value could be used clinically to predict shoulder dystocia. RESULTS: Thirty-one patients, six with dystocia, were eligible for the study. The mean AD-BPD differences for those with and without shoulder dystocia were 3.1 and 2.6 cm, respectively, a statistically significant difference (P = .05). Comparing the groups with and without shoulder dystocia, no significant differences could be found in mean age, parity, weight, birth weight, or gestational age. Shoulder dystocia occurred in six of 20 patients (30%) in whom the AD-BPD difference was at least 2.6 cm but in none of 11 patients in whom it was less than 2.6 cm, also a statistically significant difference (P = .05). CONCLUSION: The AD-BPD difference was greater in borderline macrosomic fetuses of diabetic mothers who experienced shoulder dystocia than in those who had uncomplicated vaginal deliveries. Applying an AD-BPD cutoff value of 2.6 cm to this population prospectively would have provided excellent sensitivity, specificity, and predictive value in identifying those fetuses at high risk for birth injury.

Adult↗
PubMed1997

The McRoberts' maneuver for the alleviation of shoulder dystocia: how successful is it?

OBJECTIVE: Our purpose was to determine the rate of success of the McRoberts' maneuver as the initial treatment for shoulder dystocia and to compare the rate of maternal and neonatal morbidity with those cases of shoulder dystocia requiring additional obstetric maneuvers. A secondary goal was to assess those factors associated with successful McRoberts' maneuvers. STUDY DESIGN: A retrospective review of shoulder dystocia cases occurring between 1991 and 1994 was performed. The identified cases were divided into two groups on the basis of the maneuvers used to relieve the shoulder dystocia. The first group comprised cases in which the McRoberts' maneuver was used as the sole treatment and the second group consisted of cases in which additional maneuvers were subsequently used. Exclusion criteria included lack of documentation concerning the maneuvers used or cases in which the McRoberts' maneuver was not the initial technique used. The two groups were compared with respect to various antepartum, intrapartum, and neonatal characteristics. RESULTS: During the study period we identified 250 cases of shoulder dystocia among 44,072 vaginal deliveries, for an incidence of 0.57%. Of these, 236 cases (94%) fulfilled entry criteria. The McRoberts' position alone successfully alleviated the shoulder dystocia in 98 cases (42%). In the group of cases where the McRoberts' maneuver was the sole maneuver used, there were significantly lower mean birth weights (p = 0.008), shorter durations of the active phase of labor (p = 0.009), and shorter second stages (p < 0.0001). In the group of cases that required additional maneuvers to relieve the shoulder dystocia, there was a trend toward an increased incidence of postpartum hemorrhage and brachial plexus injury (p = 0.07). CONCLUSIONS: These data suggest that the McRoberts' maneuver is associated with a significant degree of success in relieving shoulder dystocia and may be associated with decreased morbidity compared with other maneuvers. On the basis of these findings, we recommend the McRoberts' maneuver as the initial technique for disimpaction of the anterior shoulder.

Adult↗
PubMed1998

Objective definition of shoulder dystocia: a prospective evaluation.

OBJECTIVE: The current study was undertaken to validate the objective definition of shoulder dystocia in a prospectively evaluated group of patients. STUDY DESIGN: Selected vaginal deliveries from January 1995 to December 1996 (N = 722) were evaluated for head-to-body delivery time and use of ancillary obstetric maneuvers. Charts were reviewed for perinatal and outcome data. RESULTS: Ninety-nine deliveries were complicated by shoulder dystocia and 623 deliveries had no shoulder dystocia. The objective definition described infants with lower 1-minute Apgar scores and increased birth weight. All fetal injuries were in the shoulder dystocia group. Duration of the second stage was significantly associated with a diagnosis of shoulder dystocia. The risk of shoulder dystocia was increased with maternal diabetes, but it was not correlated with birth weight in diabetics. CONCLUSIONS: The objective definition of shoulder dystocia identified a group of patients with an increased birth weight and risk of fetal injuries. The use of an objective definition will assist the evaluation of prophylactic and treatment proposals for shoulder dystocia.

Adult↗
PubMed2006

Maternal and anthropomorphic risk factors for shoulder dystocia.

OBJECTIVE: To study maternal and anthropomorphic parameters as potential risk factors for shoulder dystocia. MATERIAL AND METHOD: From a series of 9667 vaginal deliveries between January 1998 and December 2003, a total of 138 cases complicated by shoulder dystocia were retrospectively identified and compared with a control group of 138 uncomplicated vaginal deliveries. In addition to maternal age, parity, diabetes, body mass index (BMI), and ethnicity, anthropometric factors including maternal height-to-infant weight ratio, characteristics of labor, management techniques, and outcome were evaluated as possible risk factors for shoulder dystocia. RESULTS: The overall incidence of shoulder dystocia in this retrospective series of vaginal deliveries was 1.4%. In univariate analysis, maternal obesity (OR; 95% CI: 3.6; 2.1-6.3), diabetes (OR: 19.4; 2.5-145.7), parity greater than 2 (OR: 2.5; 1.4-4.4), maternal height-to-infant weight ratio (OR: 1.02; 1.01-1.04; P < 0.001), and infant weight-to-maternal BMI ratio (OR: 1.02; 1.01-1.03; P < 0.001) were predictive of shoulder dystocia. In multiple regression analysis, obesity and multiparity were the most significant maternal risk factors for shoulder dystocia. The only anthropometric factors associated with shoulder dystocia in multiple regression analysis were maternal height <1.55 m (OR: 6.6; 1.3-34.9) and maternal height-to-infant weight ratio (OR: 1.02; 1.01-1.05). CONCLUSION: Shoulder dystocia may be anticipated in cases involving short women and discrepancy between maternal height or weight and infant weight.

Adult↗
PubMed2006

Dystocia in beef heifers: a review of genetic and nutritional influences.

Breeding beef heifers for the first time at 15 months of age has potential to increase the efficiency of the beef breeding-cow herd. An increased incidence of dystocia in heifers calving at 2 years of age, compared to mature cows, is a major reason many farmers in New Zealand have not adopted the practice. The predominant type of dystocia affecting 2-year-old heifers is feto-maternal disproportion, a condition in which the fetus is too large relative to the size of the heifer's pelvis. Reducing birthweight of the calf is a means of reducing the incidence of dystocia. Birthweight and length of gestation are determined by genotype of the calf, maternal genetic effects and environmental effects. Bulls with low estimated breeding values for birthweight have been selected for mating heifers; however, the positive genetic correlation between birthweight and mature weight meant that the progeny of these bulls tended to be lighter at finishing, making them less desirable in the beef industry. The genotype of the dam also plays a role in determining the risk of dystocia; the maternal ability of the dam to nurture the fetus influences birthweight, and the dam's genetic potential for growth influences the size of her pelvic area. Heavy heifers tend to produce high birthweight calves, counteracting the reduction in the incidence of dystocia resulting from the larger pelvis in larger heifers. Manipulating feeding level during pregnancy offers an alternative method for manipulating the birthweight of calves. Little is known about the effects of nutrition in early gestation on placental development or birthweight of calves. No differences in the birthweight of calves have been observed in response to variation in feeding in mid-pregnancy, and variable responses in birthweight and the incidence of dystocia to feeding in the third trimester of pregnancy have been reported. Differences in birthweight have not always resulted in differences in the incidence of dystocia, primarily due to differences in liveweight of the heifer also induced by feeding regimens. Variability in the incidence of dystocia in response to feeding level in the third trimester of pregnancy makes it difficult to make recommendations for the feeding of heifers at this stage of gestation. More research is needed into the effects of nutrition in early gestation on fetal and placental development in cattle.

Animal Nutritional Physiological Phenomena↗
PubMed2005

Trends in the rate of shoulder dystocia over two decades.

OBJECTIVE: To describe the trend in the rate of shoulder dystocia over twenty-four years and identify the risk factors related to the occurrence of dystocia. METHODS: Data was obtained from Maryland State regarding all vaginal deliveries that occurred during six different time periods at five-year intervals since 1979. Trends in the rate of shoulder dystocia, episiotomy, forceps and vacuum delivery were examined. RESULTS: There were a total of 277 974 vaginal deliveries. The overall rate of shoulder dystocia was 1.29% (n = 3590). Induction of labor (adjusted OR 1.2, 1.1-1.3), presence of diabetes (gestational (OR 1.9, 1.7-2.3) or pre-gestational (OR 3.8, 2.7-5.4)), fetal macrosomia (OR 5.1, 4.1-6.3) use of episiotomy (OR 1.6, 1.5-1.8), forceps (OR 1.3, 1.0-1.8) or vacuum (OR 2.3, 2.0-3.9) at delivery were associated with a higher rate of shoulder dystocia. TREND: There was an increase in the rate of shoulder dystocia from 0.2% in 1979 to 2.11% in 2003. In addition there was a drop in the overall episiotomy rate from 73.67% to 23.94% and increase in the use of vacuum from 0.1% to 8.36%. CONCLUSION: The rate of shoulder dystocia has increased by 10 fold during the study period. The use of episiotomy either at spontaneous delivery or instrumental delivery does not appear to decrease the occurrence of shoulder dystocia.

Adolescent↗
PubMed2001

Risk factors for dystocia in farmed red deer (Cervus elaphus).

OBJECTIVE: To analyse data from a study of deer herd health and productivity to identify potential risk factors for the occurrence of dystocia. DESIGN: A 2-year longitudinal observational study of 14 red deer farms was carried out in New Zealand. About 2700 hinds were monitored each year for individual characteristics including body condition score (BCS), and reproductive performance. Grazing and calving management practices were recorded. During calving, farmers recorded calving difficulties (dystocia) that needed human assistance or caused the death of the hind. Risk factors potentially affecting the occurrence of dystocia were identified and analysed by multivariable statistical techniques. RESULTS: The percentage of hinds with dystocia was 0.52% (95% CI 0.32 to 0.78). Hinds with a post-winter BCS over 3.5 were 2.7 times as likely to experience dystocia as hinds scoring 3.5 or less. Given the same BCS class, bodyweight gain in late pregnancy was associated with an increased risk of dystocia. Grazing steep paddocks in the last trimester of pregnancy decreased the risk of dystocia in hinds with a BCS over 3.5. CONCLUSIONS: The risk of dystocia on red deer farms may be reduced if key individual animal, management and environmental factors are optimal.

Animal Husbandry↗
PubMed1983

Factors affecting and prediction of dystocia in Charolais heifers.

Calving difficulty at first and second parturition, using data recorded on 476 purebred Charolais heifers from a ranch in Southeastern Arizona, were analyzed by analysis of variance, step-wise multiple regression and discriminant analysis. Dystocia score (1 = no assistance through 4 = extreme difficulty) was the dependent variable with dam and calf effects independent variables. In this herd, 31.1 and 15.0% of the heifers experienced calving difficulty at first and second parturition, respectively. Birth weight of calf was the most important factor influencing dystocia, accounting for 71 and 61% of the total variation explained by the analysis of variance model when calf effects as well as dam effects were included at first and second parturition. Mean birth weight was 39.0 kg for primiparous heifers and 44.3 kg for second-half cows. A significant increase in dystocia (at both first and second parturition) occurred among male calves with birth weights of 45.5 kg or greater. At first parturition, no significant increase in dystocia occurred among female calves until birth weight exceeded 50 kg. Birth weight was not a significant factor influencing dystocia for female calves at second parturition. Yearling weight of cow and dystocia score of cow's dam were the only significant dam variables, and only at first parturition. Pelvic height measurements did not significantly affect dystocia scores at either parturition. A reasonably accurate prediction of dystocia based on the variables included in this study would be impossible, even if some means were devised to reliably predict birth weight of the calf.

Age Factors↗
PubMed2007

Retrospective study of dystocia in mares at a referral hospital.

REASONS FOR PERFORMING STUDY: The period between the onset of dystocia and its resolution has an important bearing on fetal outcome. There are few published data on which to base decisions regarding optimum management of cases in practice. OBJECTIVES: To evaluate and compare the effects of a coordinated dystocia management protocol (CDMP) with that of a previous protocol of random management on time to resolution and outcome in both an emergency dystocia referral population of mares (referred emergency cases: EM) and in a population of mares residing in hospital due to high risk pregnancy (HRP) concerns that then experience dystocia at parturition. METHODS: Retrospective study performed at a university hospital referral centre of cases presenting from 1991-2004 divided into Group 1 (pre-CDMP) and Group 2 (CDMP). RESULTS: Medical records of 71 cases with dystocia were retrieved and data recorded. For referred emergency cases (EM), time from hospital presentation to resolution decreased significantly by 32 min (P = 0.03) after institution of CDMP. Survival rate of mares at discharge was 86%. Survival of EM foals was low, with 10% in Group 1 and 13% in Group 2, surviving to discharge. For EM foals delivered alive, survival to discharge was 30% and 43% in Groups 1 and 2, respectively. Median Stage II was significantly (P < 0.001) different at 71 and 282 min for EM foals delivered alive vs. those not alive at delivery, respectively. Median duration of Stage II was also significantly (P < 0.001) different between EM foals surviving and not surviving to discharge, at 44 and 249 min, respectively. Survival of HRP dystocia foals to discharge was 79%. CONCLUSIONS: Although CDMP reduced the time from presentation at the hospital to resolution significantly for EM, total duration of Stage II for EM was unchanged, as was foal outcome. POTENTIAL RELEVANCE: Very early referral of mares with dystocia to referral centres with dystocia management protocols may improve fetal outcome as increased duration of Stage II in the horse affects fetal outcome negatively.

Animals↗
PubMed1980

Relationship of dystocia transmitting ability with type and production transmitting ability in Holstein bulls.

Relationships of transmitting ability for dystocia with transmitting abilities for type and production in Holstein bulls were estimated. Genetic correlations between dystocia transmitting ability with Predicted Difference (PD) were: milk .00, fat .00, test -.02, and dollars .00. Genetic correlations for transmitting ability of dystocia were -.28 with Predicted Difference Type and -.23 with Type Production Index. Correlation indicated improved conformation will increase dystocia. The relationship of transmitting abilities from Mating Appraisal for Profit with dystocia indicated that scale (size) has a major effect on the type-dystocia relationship. Large size results in both high type classification and increased dystocia. Correlations of rump and center support with dystocia were also in excess of .20.

Animals↗
PubMed1992

The diagnosis and management of dystocia of the shoulder.

Dystocia of the shoulder is an unpredictable obstetric emergency that may result in injury to the mother or fetus. In an effort to reduce such risks, attempts have been made to identify patients having a fetus who may subsequently develop shoulder dystocia. The literature, however, clearly reflects that even the combination of prenatal historic facts, estimated fetal weight and sequence of intrapartum events is ineffective in prospectively identifying infants whose births are complicated by shoulder dystocia. During a ten year period at the University of Mississippi Medical Center, the incidence of macrosomia, shoulder dystocia and subsequent brachial plexus injury was reviewed. The majority of instances (89 percent) of shoulder dystocia occurred in patients weighing less than 8 pounds 13 ounces at birth. In the current retrospective review, only 11 percent of the women had risk factors for macrosomia or shoulder dystocia and among these, none were identified prospectively. Additionally, 91 percent of patients with brachial plexus injury recovered with no sequelae. One instance of brachial plexus injury occurred at the time of cesarean section. These data reveal that macrosomia and subsequent shoulder dystocia cannot be predicted. Therefore, it is not feasible to prevent brachial plexus injury prospectively by prophylactic cesarean section. Great clinical acumen and technical expertise by the obstetrician using a variety of methods may be useful in avoiding, as much as possible, injury to the mother and fetus when shoulder dystocia does occur.

Birth Weight↗
PubMed1980

Crossbreeding in tropical sheep: incidence of dystocia and parturition losses.

Studies were carried out on the incidence of dystocia and parturition losses during a crossbreeding experiment involving 96 West African Dwarf (WAD) ewes mated with rams of 4 breeds--WAD, Ouda, Permer and Yankassa. Results obtained indicated 8 (5.7%) cases of dystocia and 20 (10.64%) cases of stillbirths or death of lambs at birth. The WAD sires were not associated with dystocia or stillbirths but other sire groups were involved in both. All the difficult parturitions occurred during the rainy season while all stillbirths not associated with dystocia occurred during the dry season. The sires used and the level of feeding the ewes during pregnancy may be associated with the dystocia cases and parturition losses recorded. Eighty per cent of the dystocias involved ram lambs. The mean gestation period of the ewes that lambed during the dry season was significantly (P < 0.01) longer than that of the rainy season group. Application of traction and Caesarean operation were used in the treatment of dystocia cases.

Animals↗
PubMed2005

Accuracy of estimated fetal weight in shoulder dystocia and neonatal birth injury.

OBJECTIVE: This study was undertaken to determine whether there is any difference in the rate of error of estimated fetal weight (EFW) in cases of shoulder dystocia compared with controls. STUDY DESIGN: Women whose delivery was complicated by shoulder dystocia were studied and compared with a control group matched for parity, race, labor type (spontaneous or induced), and birth weight (BW). Accuracy (%) was defined as [(EFW-BW)/BW] x 100. The primary outcome of the study was rate of EFW underestimation error 20% or greater. RESULTS: During the 5-year study period, there were 206 cases of shoulder dystocia that met all study criteria. There was no difference in the number of patients that had EFW underestimation error 20% or greater (shoulder dystocia 9.8% vs control 12.8%; P = .38). There was also no difference in the number of patients that had EFW underestimation error 20% or greater between shoulder dystocia with and without injury (injury 8.3% vs no injury 7.1%; P = .79). CONCLUSION: EFW underestimation error in cases of shoulder dystocia is an infrequent event and does not occur more often than in deliveries without shoulder dystocia.

Adolescent↗
PubMed2005

Shoulder dystocia: are historic risk factors reliable predictors?

OBJECTIVE: Our purpose was to determine the rate of associated risk factors for shoulder dystocia from a large cohort of patients delivered within our Southern California perinatal program. STUDY DESIGN: A retrospective analysis was performed of patients delivered from January 1991 to June 2001. Patients with and without shoulder dystocia were identified from our computer-stored perinatal database and compared. Statistical methods used included: chi 2 test, t test, calculation of odds ratios, and Fisher exact test, as indicated. RESULTS: Among the 267,228 vaginal births during the study period, there were 1,686 cases of shoulder dystocia (rate 0.6%). Rates for operative vaginal delivery, diabetes, epidural use, multiparity, and postdatism were similar among cases with and without shoulder dystocia. The clinical triad of oxytocin use, labor induction, and birth weight greater than 4,500 g yielded a cumulative odds ratio of 23.2 (95% CI 17.3-31.0) for shoulder dystocia, but its sensitivity and positive predictive value were only 12.4% and 3.4%, respectively. CONCLUSION: Historic obstetric risk factors for shoulder dystocia are not useful predictors for the event. Furthermore, although shoulder dystocia was observed more frequently with increasing birth weight, current limitations in estimating birth weight antenatally with accuracy preclude its practical use as a reliable predictor.

Adult↗