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PubMed2006

Determining factors associated with shoulder dystocia: a population-based study.

OBJECTIVE: The study was aimed to define obstetric factors associated with shoulder dystocia. METHODS: A population-based study comparing all singleton, vertex, term deliveries with shoulder dystocia with deliveries without shoulder dystocia was performed. Statistical analysis was done using multiple logistic regression analysis. RESULTS: Shoulder dystocia complicated 0.2% (n = 245) of all deliveries included in the study (n = 107965). Independent risk factors for shoulder dystocia in a multivariable analysis were birth-weight > or =4000 g (OR = 24.3; 95% CI 18.5-31.8), vacuum delivery (OR = 5.7, 95% CI 3.4-9.5), diabetes mellitus (OR = 1.7, 95% CI 1.2-2.5) and lack of prenatal care (OR = 1.5, 95% CI 1.1-2.3). A significant linear association was found between birth-weight and shoulder dystocia, using the Mantel-Haenszel procedure. Pregnancies complicated with shoulder dystocia had higher rates of third-degree perineal tears as compared to the comparison group (0.8% versus 0.1%; P < 0.001). Similarly, perinatal mortality was higher among newborns delivered after shoulder dystocia as compared to the comparison group (3.7% versus 0.5%; OR = 7.4, 95% CI 3.5-14.9, P < 0.001). In addition, these newborns had higher rates of Apgar scores lower than 7 at 1 and 5 min as compared to newborns delivered without shoulder dystocia (29.7% versus 3.0%; OR = 13.8, 95% CI 10.3-18.4, P < 0.001 and 2.1% versus 0.3%; OR = 7.2, 95% CI 2.8-18.1, P < 0.001, respectively). Combining risk factors such as large for gestational age, diabetes mellitus and vacuum delivery increased the risk for shoulder dystocia to 6.8% (OR = 32.6, 95% CI 10.1-105.8, P < 0.001). CONCLUSIONS: Independent factors associated with shoulder dystocia were birth-weight > or =4000 g, vacuum delivery, diabetes mellitus and lack of prenatal care.

Adult↗
PubMed2002

Erb's palsy without shoulder dystocia.

OBJECTIVES: The purpose of this commentary is to review certain articles which have provided evidence that Erb's palsy can occur without associated shoulder dystocia. The mechanism of the specific cause of the injury will be described. METHODS: Prior to the last 10-12 years it was assumed that Erb's palsy occurred exclusively with and was the result of shoulder dystocia. Gonik et al. [Am J Perinat 1991;8:31-34], reported on a research study based on the premise that when Erb's palsies occurred there must have been shoulder dystocia present but it went undetected by the delivering physician. Subsequently Gherman [Am J Obstet Gynecol 1998;178:423-427], published a detailed study which carefully looked at multiple aspects of shoulder dystocia including those similar injuries occurring with and without associated shoulder dystocia. RESULTS: Both Gonik's and Gherman's research revealed distinct maternal and newborn differences when comparing Erb's palsy occurring with and without associated shoulder dystocia. These differences, which have nothing to do with the ability to recognize shoulder dystocia, provide conclusive evidence that Erb's palsy does occur without associated shoulder dystocia. CONCLUSIONS: Therefore, Gonik's original premise, that shoulder dystocia must have been present if Erb's palsy occurred, is not supported. This brings into question the cause of Erb's palsy in those cases without shoulder dystocia. The maternal forces are the most likely cause both with and without shoulder dystocia.

Birth Injuries↗
PubMed1998

A six-year retrospective analysis of shoulder dystocia and delivery of the shoulders.

OBJECTIVE: To investigate the diagnosis, incidence and management of shoulder dystocia. DESIGN: Retrospective review of all the deliveries between 1988 and 1993 which were coded on the computer data base as 'moderate difficulty with the shoulders' or 'shoulder dystocia'. SETTING: A teaching hospital in the south of England. PARTICIPANTS: The study population consisted of 15,658 women who had cephalic vaginal deliveries of babies weighing > 2.5 kg. The sample consisted of the 257 women reported to have moderate difficulty with the shoulders or shoulder dystocia at delivery. FINDINGS: There was a significant fall in the reported incidence of shoulder dystocia during the period under investigation. Eighty-six (1.1%) of the deliveries between 1988 and 1990 were reported to have been complicated by shoulder dystocia. In 1991 a second option was introduced to allow both shoulder dystocia or moderate difficulties with the shoulders to be coded after delivery. Following this change in categorisation, the incidence of shoulder dystocia was reduced to 30 (0.6%) reported cases in 1992-1993. Over the same period the reported incidence of moderate difficulty rose significantly from 29 (1.1%) in 1992 to 60 (2.4%) in 1993 (P < 0.001). Disparity was noted between the experience of practitioners and contemporary definitions of shoulder dystocia and this was highlighted by the number of reported cases of moderate difficulty. In this study practitioners used the term shoulder dystocia in a general sense to describe a range of difficulties encountered with the delivery of the shoulders and they identified many varied manifestations. In comparison, contemporary literature describes shoulder dystocia as a discrete entity. KEY CONCLUSIONS: Shoulder dystocia is a complex clinical scenario and perceptions of the incidence may be influenced by alterations in the delivery technique and changes in the diagnosis and documentation. IMPLICATIONS FOR PRACTICE: The application of traction may interfere with the normal mechanisms of labour and the spontaneous birth of the shoulders, whilst increasing the risk of trauma to the baby. It may be unnecessary to use such interventions routinely in the care of normal labouring women.

Birth Weight↗
PubMed1993

Shoulder dystocia: an analysis of risks and obstetric maneuvers.

OBJECTIVE: The purpose of this study was to determine whether there is a risk profile for predicting or preventing shoulder dystocia and whether any of the obstetric maneuvers to disimpact a shoulder reduce the likelihood of permanent injury. STUDY DESIGN: A retrospective analysis of 14,297 parturients with 12,532 vaginal deliveries and 1765 cesarean sections (12.4%) from January 1986 through June 1990 was performed. A total of 204 maternal and infant charts, related to shoulder dystocia or neonatal injury, were reviewed in depth for age, parity, episiotomy, type of delivery, hemorrhage, maternal obesity, diabetes, weight gain, fetal weight, sex, and Apgar scores. In addition, the type of maneuver or combination thereof used to relieve the dystocia, type of injury to the infant, and follow-up of the injury were reviewed. RESULTS: The 185 coded episodes of shoulder dystocia represent 1.4% of all vaginal deliveries (12,532). There were 42 injuries recorded: 14 fractured clavicles and 28 brachial plexus injuries. An additional 19 patients, not coded for shoulder dystocia, sustained 14 fractured clavicles and five brachial plexus injuries. All but one of the brachial plexus injuries resolved by 6 months. The occurrence of shoulder dystocia increased in direct relationship to the birth weight and becomes significant in newborns over 4000 gm (p < 0.01). The occurrence of a previous large infant was also a significant risk factor (p < 0.01). Diabetes and midforceps delivery become significant factors only in the presence of a large fetus. Obesity, multiparity, postdate pregnancy, use of oxytocin, low forceps delivery, episiotomy, and type of anesthesia were unrelated to shoulder dystocia. No delivery method was without injury. CONCLUSIONS: This study clearly indicates that most of the traditional risk factors for shoulder dystocia have no predictive value, shoulder dystocia itself is an unpredictable event, and infants at risk for permanent injury are virtually impossible to predict. In addition, no delivery method in shoulder dystocia was superior to another with respect to injury. Thus no protocol should serve to substitute for clinical judgment.

Delivery, Obstetric↗
PubMed1995

An objective definition of shoulder dystocia: prolonged head-to-body delivery intervals and/or the use of ancillary obstetric maneuvers.

OBJECTIVE: To generate an objective definition of shoulder dystocia by timing the events of the second and third stages of labor, and to define the true incidence of shoulder dystocia. METHODS: In 34 arbitrarily selected 24-hour time periods, a nonparticipating observer prospectively timed intervals of the second stage of labor in all vaginal deliveries and recorded the use of obstetric maneuvers (McRoberts, episiotomy after delivery of the fetal head, intentional extension of initial episiotomy after delivery of the fetal head, suprapubic pressure, posterior arm rotation to an oblique angle, rotation of the infant by 180 degrees, delivery of the posterior arm, and general anesthesia) and whether the obstetric attendant identified a delivery with shoulder dystocia. All data are reported as mean +/- standard error of the mean. RESULTS: Two hundred fifty deliveries were timed and recorded prospectively. Mean intervals (in seconds) in nonmaneuver patients were as follows: head to anterior shoulder 14.8 +/- 1.0, anterior to posterior shoulder 3.9 +/- 0.6, posterior shoulder to body 5.4 +/- 0.8, and total head-to-body time 24.2 +/- 1.3. Three groups of patients were defined after delivery. The maneuver group consisted of 27 patients requiring any of the aforementioned obstetric maneuvers, although the obstetric attendant identified only 16 of these as shoulder dystocia. The prolonged delivery group included 29 patients with the head-to-body delivery interval exceeding the mean plus two standard deviations (60 seconds) of nonmaneuver patients. Sixteen of the 27 maneuver patients were identified as prolonged. The 210 not identified as maneuver or prolonged were considered to be normal. Normal patients had a significantly lower newborn birth weight (3269 +/- 38 g), and a lower proportion of 1-minute Apgar scores of 7 or less (11%) than did the maneuver (4247 +/- 86 g, 41%) and prolonged groups (3952 +/- 118 g, 34%). Defining shoulder dystocia as a prolonged head-to-body delivery time and/or the use of obstetric maneuvers identified 40 patients who had birth weights and 1-minute Apgar scores significantly different from the normal patients. CONCLUSION: The incidence of shoulder dystocia, as defined by the use of ancillary obstetric maneuvers, is higher than that reported previously, and the reporting of shoulder dystocia appears to be unreliable. The interval from head-to-body delivery is delayed significantly in patients with shoulder dystocia, despite the lack of recognition of shoulder dystocia. We propose defining shoulder dystocia as a prolonged head-to-body delivery time (eg, more than 60 seconds) or the need for ancillary obstetric maneuvers.

Adult↗
PubMedDate not supplied

Shoulder dystocia: etiology, common risk factors, and management.

Shoulder dystocia and brachial plexus injury occur in 0.5% to 1.5% of all births. Risk factors for both include maternal obesity, excessive prenatal weight gain, maternal diabetes, protracted labor, and fetal macrosomia. These factors are involved in only about 50% of births complicated by shoulder dystocia or brachial plexus injury. Shoulder dystocia has a low recurrence rate (9.8%-16.7%), although history of previous shoulder dystocia is the most reliable predictor of occurrence. Brachial plexus injury is the most common morbidity associated with shoulder dystocia, but 50% of newborns who present with this injury were not subject to shoulder dystocia at birth. Most brachial plexus injuries are transient, although 5% to 22% become permanent. Shoulder dystocia followed by permanent brachial plexus injury or mental impairment is one of the leading causes of malpractice allegations. Prompt assessment and management of shoulder dystocia and preparation to maximize the efficiency of shoulder dystocia maneuvers are critical. Documentation of the appropriate use of maneuvers to relieve shoulder dystocia demonstrates standard of care practice, thereby decreasing the potential for successful malpractice allegations.

Brachial Plexus↗
PubMed1998

Shoulder dystocia and associated risk factors with macrosomic infants born in California.

OBJECTIVE: The purpose of this study was to examine the 1-year incidence statewide in California of shoulder dystocia and its associated risk factors. STUDY DESIGN: With a data set that contains computer-linked records from the birth certificate and hospital discharge records of both mother and baby, all births of infants >3500 g in >300 civilian acute care hospitals in California in 1992 were analyzed. All cases of shoulder dystocia were identified from discharge records, birth certificates, or both and were analyzed with both bivariate and multivariate techniques to identify specific risk factors. RESULTS: A total of 175,886 vaginal births of infants >3500 g were included in our database, of which 6238 infants (3%) had shoulder dystocia. The percentages of births complicated by shoulder dystocia for unassisted births not complicated by diabetes were 5.2% for infants 4000 to 4250 g, 9.1% for those 4250 to 4500 g, 14.3% for 4500 to 4750, and 21.1% for those 4750 to 5000 g. Shoulder dystocia increased by approximately 35% to 45% in vacuum- or forceps-assisted births to nondiabetic mothers. Similar increases were seen in unassisted births to diabetic mothers. The risk of shoulder dystocia for assisted births to diabetic mothers was even more dramatic: 12.2% for infants 4000 to 4250 g, 16.7% for those 4250 to 4500 g, 27.3% for those 4500 to 4750 g, and 34.8% for those 4750 to 5000 g. After controlling for other parameters, there was an increased risk of shoulder dystocia associated with diabetes (odds ratio 1.7), assisted delivery (odds ratio 1.9), and induction of labor (odds ratio 1.3). Rates of birth trauma, asphyxia, and length of stay were all increased among births complicated by shoulder dystocia. CONCLUSION: This information on the incidence of shoulder dystocia and associated risk factors for a large statewide population may assist providers of obstetric care in counseling patients when macrosomia is suspected. The inaccuracy of estimating fetal weight is a severe limitation in attempting to establish guidelines designed to prevent shoulder dystocia.

Birth Weight↗
PubMed2001

How to predict recurrent shoulder dystocia.

OBJECTIVE: Our aim was to determine the rate and risk factors for recurrent shoulder dystocia. STUDY DESIGN: A retrospective analysis of patients diagnosed with shoulder dystocia was performed by searching a computerized database from January 1, 1993, to June 30, 1999 for the following information: (1) vaginal deliveries, either spontaneous or operative, (2) shoulder dystocia, (3) birth weight, (4) duration of second stage of labor, (5) parity, and (6) gestational diabetes. Statistical analyses included chi(2) and t test. RESULTS: There were 39,681 vaginal deliveries with 602 (1.5%) complicated by shoulder dystocia. Sixty-six patients underwent a subsequent vaginal delivery, and 11 (16.7%) experienced another shoulder dystocia. The odds ratio for a recurrent shoulder dystocia was 10.98 (P <.000001). Nine of the 11 patients with recurrent shoulder dystocia compared with 28 of 55 without a recurrence were nulliparous women in their index pregnancy (P <.001). The mean fetal weights were 3885 g in the recurrent dystocia group and 3702 g in the group without recurrence (P <.03). Gestational age, operative delivery, and gestational diabetes were similar in the two groups. CONCLUSION: Factors that appear to increase the recurrence risk of shoulder dystocia include fetal weight and maternal parity. Prior shoulder dystocia is the single greatest predictive factor.

Dystocia↗
PubMed1985

Risk factors for shoulder dystocia.

The risk factors associated with the occurrence of shoulder dystocia were examined in the general obstetrical population of women delivering vaginally. An increasing incidence of shoulder dystocia was found as infant birth weight increased. Although one-third of shoulder dystocia occurred in pregnancies at 42 + weeks, except for those resulting in infants weighing 4500 + g, the vast majority was unaffected by shoulder dystocia. The incidence of shoulder dystocia in nondiabetic gravidas delivering an infant weighing 4000 to 4499 and 4500 + g vaginally was 10.0 and 22.6%, respectively. Within the 4000- to 4499-g group, no labor abnormality was clearly predictive; however, in the heaviest birth weight group, an arrest disorder heralded a shoulder dystocia in 55.0% of cases. Diabetics experienced more shoulder dystocia than nondiabetics. Among them, 31% of vaginally delivered neonates weighing 4000 + g experienced shoulder dystocia. Nevertheless, the risk factors of diabetes and large fetus (4000 + g) could predict 73% of shoulder dystocia among diabetics; large fetus along flagged 52% of shoulder dystocia in nondiabetics. Cesarean section is recommended as the delivery method for diabetic gravidas whose estimated fetal weight is 4000 + g. If others confirm the risk, the authors advise serious consideration of cesarean section for gravidas who are carrying fetuses estimated to be 4500 + g and who experience an abnormal labor.

Apgar Score↗
PubMed1978

Shoulder dystocia. A complication of fetal macrosomia and prolonged second stage of labor with midpelvic delivery.

Shoulder dystocia is an infrequently encountered obstetric emergency varying in incidence from 0.15 to 0.60% of all deliveries. Previously identified risk factors include maternal obesity, previous infants weighing greater than 4 kg, maternal diabetes, and fetal macrosomia (greater than 4 kg). To evaluate the role of prolonged second stage of labor (PSS) as a warning sign for shoulder dystocia, 9864 deliveries at LAC-USC Women's Hospital were retrospectively reviewed. Ninety percent delivered vaginally and 4.89% had PSS with midpelvic delivery. Shoulder dystocia occurred in 0.37% of all vertex vaginal deliveries. In the absence of PSS and midpelvic delivery, the incidence of shoulder dystocia was 0.16%. However, with PSS and midpelvic delivery, the incidence of shoulder dystocia was 4.57% (P less than 0.01). Infants weighing in excess of 4 kg were at increased risk of shoulder dystocia compared with infants weighing less than 4 kg. When PSS occurred and midpelvic delivery was attempted, the incidence of shoulder dystocia was 21% in infants weighing in excess of 4 kg; 8% had had failed vaginal delivery. All shoulder dystocias and failed vaginal deliveries occurred after use of the vacuum extractor. Immediate neonatal injury was apparent in 47% of infants with shoulder dystocia after PSS with midpelvic delivery. There were no maternal or fetal deaths related to shoulder dystocia during the study period.

Birth Weight↗
PubMed1995

Recurrence rate of shoulder dystocia.

OBJECTIVE: Shoulder dystocia continues to be a major complication of obstetrics, and several factors have been identified to help predict its occurrence. A previous shoulder dystocia is one of the risk factors. However, the recurrence rate is unknown. The purpose of this study is to report the recurrence rate of shoulder dystocia. STUDY DESIGN: Our obstetric database was used to identify all vaginal deliveries between January 1983 through December 1992. A subset of vaginal deliveries complicated by shoulder dystocia was selected from this database. These records were reviewed to identify subsequent pregnancies, outcomes, risk factors, and demographic data. RESULTS: During the study period there were 37,465 total vaginal deliveries, with shoulder dystocia complicating 747 (overall rate 2%). Of these 747 cases, 101 patients had 123 subsequent vaginal deliveries, with shoulder dystocia complicating 17 of these pregnancies (13.8% recurrence rate, p < 0.0001). Comparisons were made between those patients with recurrent shoulder dystocia. CONCLUSION: Shoulder dystocia recurred at a rate approximately seven times higher than our primary rate. Whether patients with a history of shoulder dystocia should be offered an elective abdominal delivery requires further investigation.

Adolescent↗
PubMed2006

The relationship of fetal position and ethnicity with shoulder dystocia and birth injury.

OBJECTIVE: The objective of this study was to examine factors associated with the occurrence of shoulder dystocia and subsequent perinatal outcomes. STUDY DESIGN: We conducted a retrospective cohort study of 29,612 consecutive term, singleton, vertex vaginal deliveries. The primary outcome was reported shoulder dystocia. Fetal position, ethnicity, and their interaction terms were examined along with maternal characteristics, induction and length of labor, operative vaginal delivery, epidural, and birth weight in both bivariate and multivariate analyses. RESULTS: Among women who met study criteria, 524 (1.8%) experienced a shoulder dystocia. African American women had the highest risk of shoulder dystocia (2.6%), compared with other races/ethnicities (P = .001). Women who delivered in occiput posterior position were noted to have a lower risk for shoulder dystocia (1.1%) as compared with occiput anterior position (1.8%, P = .046). However, in the setting of a shoulder dystocia, a higher risk of brachial plexus injury was observed in neonates delivered in occiput posterior position (adjusted odds ratio 10.4, 95% confidence interval 3.03 to 35.88) by vacuum-assisted vaginal delivery (adjusted odds ratio 3.24, 95% confidence interval 1.37 to 7.67) and neonates weighing 4000 g or more (adjusted odds ratio 2.53, 95% confidence interval 1.09 to 5.85). CONCLUSION: Overall African American women have an increased risk of shoulder dystocia, but their neonates are not more likely to experience birth injury. Although occiput posterior position has a protective effect for shoulder dystocia, the risk of brachial plexus injury is increased in the setting of a persistent occiput posterior delivery. These factors should be used to consider a patient's prospective risk for shoulder dystocia and associated outcomes.

Adult↗
PubMed1998

Familial occurrence of dystocia.

OBJECTIVE: A cohort study was conducted to determine the risk of dystocia for women whose mothers, sisters, or twin sisters had dystocia during childbirth. STUDY DESIGN: A linked database was constructed between 2 separate Swedish birth registries. Obstetric data on mothers giving birth to daughters during the period 1955 to 1972 were studied. Among these daughters, sister-couples and twins were identified. The daughters subsequently became mothers during 1973 and 1990 and obstetric data on the first deliveries were also studied. RESULTS: If a mother had dystocia when delivering her eldest daughter, this daughter had an increased risk of dystocia during her own first childbirth (odds ratio 1.7, 95% confidence interval 1.2 to 2.4). If the mother had an assisted instrumental delivery (vacuum extraction, forceps, or cesarean section) because of dystocia, there was a higher risk for her daughter to have an instrumental delivery because of dystocia (odds ratio 1.8, 95% confidence interval 1.0 to 3.1). Among primiparous sisters the risk of an instrumental delivery because of dystocia in a younger sister was more than tripled (odds ratio 3.5, 95% confidence interval 2.1 to 5.8) if her elder sister had a dystocic labor requiring instrumental intervention. The risk among twins increased more than 20-fold (odds ratio 24.0, 95% confidence interval 1.5 to 794.5) if 1 twin sister had dystocia during her first childbirth. CONCLUSION: Dystocia has a familial occurrence, suggesting a possible genetic factor explaining inefficient uterine action.

Cross-Sectional Studies↗
PubMed2005

Magnetic resonance imaging pelvimetry and the prediction of labor dystocia.

OBJECTIVE: To study whether magnetic resonance imaging (MRI) pelvimetry has the ability to identify those women who require cesarean delivery for labor dystocia. METHODS: From July 2003 to April 2004, nulliparous women scheduled for a labor induction for prolonged pregnancy (42 weeks) were asked to participate in a pelvimetry study. Those who consented underwent fast-acquisition MRI that included two 90-second acquisitions to evaluate fetal biometry and volumetry and maternal pelvimetry, including novel measurements of pelvic bony and soft tissue volumes as determined by MRI. Information about each patient's pregnancy, labor course, and neonatal outcome was prospectively collected. Pelvimetry results for those women undergoing operative delivery for labor dystocia were compared with those who did not. Single fetal and maternal pelvic measurements, as well as ratios of both, were analyzed. In addition, previously described radiographic pelvimetry techniques and formulas to predict dystocia were used. RESULTS: One hundred one women underwent MRI, and 22 of these underwent cesarean delivery for dystocia. No single fetal measurement was statistically associated with dystocia. Several maternal pelvic measures, fetal-to-maternal ratios, and previously reported pelvimetric techniques were significantly associated with dystocia. The ratio of magnetic resonance (MR) fetal head volume to pelvic soft tissue volume had statistical significance (P = .04). Receiver operator characteristic curves were developed for the different measurements, ratios, and formulas studied to assess whether any of the techniques could accurately predict labor dystocia requiring operative delivery. The area under the curve values ranged from 0.6 to 0.8, with the ratio of MR head volume to pelvic soft tissue being 0.7. These values suggest that MRI can identify those women at greatest risk for dystocia, but it cannot with accuracy predict which ones will require a cesarean. CONCLUSION: We found significant associations with MRI pelvimetry and labor dystocia, but MRI was not a significant improvement over previously described pelvimetric techniques. LEVEL OF EVIDENCE: II-3.

Adult↗
PubMed2004

Genetic influence on dystocia.

BACKGROUND: Dystocia-prolonged and difficult labor-is a common and worldwide problem during parturition. Epidemiological studies have suggested a familial aggregation. This study aimed to quantify the genetic influence (i.e. the heritability) on dystocia. METHODS: A retrospective study of all births in Sweden from 1973 through 1997 was undertaken. Data from the population-based Swedish Birth, Twin and National Family Registers were linked on an individual basis. In total, 2,539,534 births were analyzed. Relationships between sibling and mother-daughter pairs were established. The relative risk for dystocia was calculated. Model-fitting (Mx) was used to estimate the relative contribution of genetic and environmental factors for liability to dystocia. RESULTS: In all, 190,747 women were diagnosed with dystocia. Measures of familial similarity (relative risks and correlation of liability) for dystocia were higher in monozygotic than in dizygotic twins, other sibling pairs and mother-daughter pairs. Correlation of liability was also higher in full-sisters than in half-sisters. Model-fitting suggested that genetic effects accounted for 28%[95% confidence interval (CI) 21-32] of the susceptibility for dystocia. CONCLUSION: Dystocia is a complex disorder of poor uterine action that is influenced by a significant genetic component as well as environmental factors. The amount of genetic influence makes it interesting to study the gene expression in these patients. Detection of the genes related to dystocia might lead to better pathophysiological understanding of this condition and the possibility of detecting these mothers before parturition.

Adult↗
PubMed1989

Shoulder dystocia--a clinical study of 56 cases.

A retrospective analysis of 17,127 singleton vaginal deliveries revealed 56 cases of shoulder dystocia giving an incidence of 0.3%. Although an increasing incidence of shoulder dystocia was noted as the infant birth-weight increased, 41% of shoulder dystocia occurred in infants of average birth-weight (2,500-3,999g). Diabetes mellitus, postmaturity, maternal weight above 90 kg were each factors associated with a large sized infant which should signal the possible occurrence of shoulder dystocia. In the present series shoulder dystocia occurred in 2.7% of all infants weighing 4,000 g or more. Diabetic women experienced shoulder dystocia more often than non-diabetics. In the diabetics 15.7% of neonates of birth-weight 4,000 g and above sustained shoulder dystocia compared to 1.6% in the nondiabetic patients. Immediate neonatal injury was apparent in 43% of infants with shoulder dystocia, Erb palsy being the commonest injury. The perinatal mortality rate in the series was 54/1,000 deliveries. There was no maternal death. To avoid the potentially lethal and dangerous complications of shoulder dystocia, all clinical and technological methods available should be utilized to detect the excessive sized infants so that abdominal delivery may be performed before it is too late.

Adult↗
PubMed1975

The incidence of dystocia in fine-wool Merino ewes.

The mean incidence of dystocia in 1,510 fine-wool Merino ewes over a ten-year period was 4.1% of ewes lambing. In the 10 year period, 10% of all neonatal mortality was attributed to dystocia and in only 23% of dystocias was lamb presentation abnormal. The incidence of dystocia was not related to age of ewe. Significantly more ewes experienced dystocia at spring than winter (P less than 0.05) or summer (P less than 0.01) lambings. The mean birth weights of dystocic single and twin born lambs were 4.19 and 3.38 kg respectively. The corresponding birth weights of lambs that did not experience dystocia were 3.69 and 3.00 kg. More ewes experienced dystocia when stocked at 12 or 16 per ha than at 8 per ha (P less than 0.05). Fifty per cent of recorded dystocias occurred in ewes stocked at 16 per ha, 40 per cent at 12 per ha and 10 per cent at 8 per ha. Ewe body weight pre-lambing was not related to the incidence of dystocia but it would appear that weaker ewes are more likely to have a difficult birth than ewes that are stronger and in better condition.

Animals↗
PubMed1976

A survey of dystocia in beef cattle in Southern Queensland.

Data relating to dystocia were obtained for 22% of beef herds in the Roma region of southern Queensland. In 1973 dystocia incidence in 23,129 maiden heifers was 12%; 4% of heifers and 7% of calves died. Thirty-five per cent of the 444 herds surveyed had more than a 10% incidence of dystocia, and 10% had more than a 30% incidence of dystocia. Only 6% of herds had no dystocia. Among the 73% of producers considering dystocia a problem in most years, 14% regarded it as a major problem. The incidence of dystocia in heifers was significantly higher in Poll Hereford than Hereford herds, which in turn were higher than other breeds of cattle. Poll Hereford and Hereford owners were the most concerned about dystocia but did not supervise calving more frequently. Dystocia and attitude were also examined in relation to degree of supervision at calving and size of the breeding herd.

Animal Husbandry↗