Effects of twinning on gestation length, retained placenta, and dystocia.
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Constraints to maximal productivity from twinning in beef cattle include increased incidence of dystocia and retained placenta, longer postpartum interval, and lower conception rate. Incidence and cause(s) of the shorter gestation length and of the increased retained placenta and dystocia associated with twinning were evaluated for 3,370 single and 1,014 twin births produced in a population of cattle selected for natural twin births. Gestation length was shorter for twin than for single pregnancies (275.6 vs. 281.3 d, P<.01) and likely contributed to the higher incidence of retained placenta associated with twin births (27.9 vs. 1.9%; P<.01). Incidence of retained placenta was also higher in the spring (March-April) than in the fall (August-September) calving season (18.3 vs. 11.4%; P<.01). The higher incidence of dystocia with twins than with singles (46.9 vs. 20.6%, P<.01) was primarily due to abnormal presentation (37.0 vs. 4.5%, respectively) of one or both twin calves at parturition. First- (40.5%) and second- (22.7%) parity dams with a single birth had more (P<.01) dystocia than older dams (13.4%), whereas dystocia was not affected (P>.10) by parity with twin births. Because of the shorter gestation length and the increased incidence of retained placenta and(or) dystocia, achievement of increased productivity with twinning in cattle necessitates intensive management of twin-producing dams and their calves during the calving season. Management of the increased dystocia can be facilitated by preparturient diagnosis of twin pregnancies, enabling timely administration of obstetrical assistance to facilitate delivery of twin calves and to increase their neonatal survival. (+info)
The influence of the obstetrician in the relationship between epidural analgesia and cesarean section for dystocia.
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BACKGROUND: The association between epidural analgesia for labor and the risk of cesarean section for dystocia remains controversial The authors hypothesized that if epidural analgesia were an important factor in determining cesarean section rates, then obstetricians with higher rates of utilization of epidural analgesia for labor would have higher rates of cesarean section for dystocia. METHODS: The frequency of use of epidural analgesia and frequency of occurrence of various patient risk factors for cesarean section were calculated for 110 obstetricians caring for > or = 50 low-risk parturients. These frequencies were compared by linear regression to obstetricians' rates of cesarean section for dystocia. Stepwise regression was used to attempt to predict obstetricians' cesarean rates from the incidence of various patient and provider risk factors. RESULTS: There was no relationship between frequency of epidural analgesia and rate of cesarean section for dystocia across practitioners (R2 = 0.019; P = 0.156). Weighting each obstetrician's data for the number of patients cared for during the study period did not change this result. Stepwise linear regression only modestly predicted obstetricians' cesarean section rates for dystocia, yielding a model containing 12 variables not including epidural analgesia (gestational age, induction of labor, maternal age, provider volume, nulliparity, and seven interactions; adjusted R2 = 0.312; P < 0.0001). CONCLUSIONS: The frequency of use of epidural analgesia does not predict obstetricians' rates of cesarean section for dystocia. After accounting for a number of known patient risk factors, obstetrical practice style appears to be a major determinant of rates of cesarean section. (+info)
Threshold-linear versus linear-linear analysis of birth weight and calving ease using an animal model: I. Variance component estimation.
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Birth weight and calving difficulty were analyzed with Bayesian methodology using univariate linear models, a bivariate linear model, a threshold model for calving difficulty, and a joint threshold-linear model using a probit approach. Field data included 26,006 records of Gelbvieh cattle. Simulated populations were generated using parameters estimated from the field data. The Gibbs sampler was used to obtain estimates of the marginal posterior mean and standard deviation of the (co)variance components, heritabilities, and correlations. In the univariate analyses, the posterior mean of direct heritability for calving difficulty was .23 with the threshold model and .18 with the linear model. Maternal heritabilities were .10 and .08, respectively. In the bivariate analysis, posterior means of direct heritability for calving difficulty were .21 and .18 for the bivariate linear-threshold and linear-linear model, respectively. Maternal heritabilities were .09 and .06, respectively. Direct heritability for birth weight was .25 for the univariate model and .26 for bivariate models. Maternal heritability was .05 for the linear-threshold model and the univariate model and .06 for the bivariate linear model. Genetic correlation between direct genetic effects in both traits was .81 for the linear-threshold model and .79 for the bivariate linear. Residual correlation was .35 for the bivariate linear model and .50 for the bivariate linear-threshold. A simulation study confirmed that the posterior mean of the marginal distribution was suitable as a point estimate for univariate threshold and bivariate linear-threshold models. (+info)
Threshold-linear versus linear-linear analysis of birth weight and calving ease using an animal model: II. Comparison of models.
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Several models were evaluated in terms of predictive ability for calving difficulty. Data included birth weight and calving difficulty scores provided by the American Gelbvieh Association from 26,006 calves born to first-parity cows and five simulated populations of 6,200 animals each. Included in the model were fixed age of dam x sex interaction effects, random herd-year-season effects, and random animal direct and maternal effects. Bivariate linear-threshold and linear-linear models for birth weight/calving ease and univariate threshold and linear models for calving ease were applied to the data sets. For each data set and model, one-half of calving ease records were randomly discarded. Predictive ability of the different models was defined with the mean square error (MSE) for the difference between a deleted calving ease score and its prediction obtained from the remaining data. In terms of correlation between simulated and predicted breeding values, the threshold models had a 1% advantage for direct genetic effects and 3% for maternal genetic effects. In simulation, the average MSE was .29 for linear-threshold, .32 for linear-linear, .37 for threshold, and .39 for linear model. For the field data set, the MSE was .31, .33, .39, and .40, respectively. Although the bivariate models for calving ease/birth weight were more accurate than univariate models, the threshold models showed a greater advantage under the bivariate model. For the purpose of genetic evaluation for calving difficulty in beef cattle, the use of the linear-threshold model seems justified. In dairy cattle, the evaluation for calving ease can benefit from recording birth weight. (+info)
Relationship of maternal plasma progesterone and estrone sulfate to dystocia in Holstein-Friesian heifers and cows.
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Thirteen primiparous and 41 multiparous Holstein-Friesian cattle were used to study the relationship between maternal plasma progesterone (P4) and estrone sulfate (E1S) concentrations and the prevalence of dystocia. The calvings in 4 heifers and 30 cows were normal (eutocia), while the calvings in 9 heifers and 11 cows were difficult (dystocia). Neither the concentrations of P4 nor E1S were different between the groups with eutocia and dystocia from days 90 to 270 of pregnancy. However, a few days prior to parturition, eutocial cows and heifers showed a sharp decline of plasma P4, while dystocial cattle did not show such a remarkable decline of P4 concentration. Plasma P4 levels in dystocial cows a few days antepartum were significantly higher than in eutocial animals (P<0.05 or P<0.01). Prepartum E1S concentrations were significantly lower (P<0.05) in dystocial than eutocial cattle during the prepartum period from days 6 to 1 in heifers and from days 3 to 1 in cows. These results suggest that insufficient production of E1S and delayed regression of the corpora lutea are possible causes of dystocia in cattle. (+info)
No mutations found in candidate genes for dystocia.
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Dystocia is a disorder characterized by prolonged or dysfunctional labour. Delivery that starts late or not at all, leads to an increased risk for Caesarean section, infant morbidity and mortality. Familial aggregations of dystocia suggest a polygenic background. We have studied three candidate genes for dystocia, i.e. the genes for testosterone 5-alpha reductase type 1, prostaglandin F2alpha receptor and endothelin 1 and performed mutational screening in 23 women with dystocia, of which 12 have affected relatives. No mutations were found, making it unlikely that any of these genes represent a major cause of dystocia in man. (+info)
Effect of mode of delivery in nulliparous women on neonatal intracranial injury.
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BACKGROUND: Infants delivered by vacuum extraction or other operative techniques may be more likely to sustain major injuries than those delivered spontaneously, but the extent of the risk is unknown. METHODS: From a California data base, we identified 583,340 live-born singleton infants born to nulliparous women between 1992 and 1994 and weighing between 2500 and 4000 g. One third of the infants were delivered by operative techniques. We evaluated the relation between the mode of delivery and morbidity in the infants. RESULTS: Intracranial hemorrhage occurred in 1 of 860 infants delivered by vacuum extraction, 1 of 664 delivered with the use of forceps, 1 of 907 delivered by cesarean section during labor, 1 of 2750 delivered by cesarean section with no labor, and 1 of 1900 delivered spontaneously. As compared with the infants delivered spontaneously, those delivered by vacuum extraction had a significantly higher rate of subdural or cerebral hemorrhage (odds ratio, 2.7; 95 percent confidence interval, 1.9 to 3.9), as did the infants delivered with the use of forceps (odds ratio, 3.4; 95 percent confidence interval, 1.9 to 5.9) or cesarean section during labor (odds ratio, 2.5; 95 percent confidence interval, 1.8 to 3.4), but the rate of subdural or cerebral hemorrhage associated with vacuum extraction did not differ significantly from that associated with forceps use (odds ratio for the comparison with vacuum extraction, 1.2; 95 percent confidence interval, 0.7 to 2.2) or cesarean section during labor (odds ratio, 0.9; 95 percent confidence interval, 0.6 to 1.4). CONCLUSIONS: The rate of intracranial hemorrhage is higher among infants delivered by vacuum extraction, forceps, or cesarean section during labor than among infants delivered spontaneously, but the rate among infants delivered by cesarean section before labor is not higher, suggesting that the common risk factor for hemorrhage is abnormal labor. (+info)
Nutrition and obstructed labor.
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Obstructed labor is one of the most common preventable causes of maternal and perinatal morbidity and mortality in developing countries. Among the common causes are cephalopelvic disproportion, malpresentation, and malposition. Recognizing the causes of obstructed labor is important if the complications are to be prevented. Adequate prevention, however, can be achieved only through a multidisciplinary approach aimed in the short term at identifying high-risk cases and in the long term at improving nutrition. Early motherhood should be discouraged, and efforts are needed to improve nutrition during infancy, childhood, early adulthood, and pregnancy. Improving the access to and promoting the use of reproductive and contraceptive services will help reduce the prevalence of this complication. (+info)