Mmp2 Deficiency Leads to Defective Parturition and High Dystocia Rates in Mice.

Parturition is the final and essential step for mammalian reproduction. While the uterus is quiescent during pregnancy, fundamental changes arise in the myometrial contractility, inducing fetal expulsion. Extracellular matrix (ECM) remodeling is fundamental for these events. The gelatinases subgroup of matrix metalloproteinases (MMPs), MMP2 and MMP9, participate in uterine ECM remodeling throughout pregnancy and parturition. However, their loss-of-function effect is unknown. Here, we determined the result of eliminating Mmp2 and/or Mmp9 on parturition in vivo, using single- and double-knockout (dKO) mice. The dystocia rates were measured in each genotype, and uterine tissue was collected from nulliparous synchronized females at the ages of 2, 4, 9 and 12 months. Very high percentages of dystocia (40-55%) were found in the Mmp2-/- and dKO females, contrary to the Mmp9-/- and wild-type females. The histological analysis of the uterus and cervix revealed that Mmp2-/- tissues undergo marked structural alterations, including highly enlarged myometrial, endometrial and luminal cavity. Increased collagen deposition was also demonstrated, suggesting a mechanism of extensive fibrosis in the Mmp2-/- myometrium, which may result in dystocia. Overall, this study describes a new role for MMP2 in myometrium remodeling during mammalian parturition process, highlighting a novel cause for dystocia due to a loss in MMP2 activity in the uterine tissue.

Obstructed uterine venous return: a preventable cause of dysfunctional labor?

Dysfunctional labor is a common cause of cesarean delivery and may be caused by myometrial hypoxia. Obstruction of uterine venous return due to compression of the inferior vena cava by the gravid uterus or the abdominal wall may be an auxiliary cause of myometrial hypoxia which aggravates other causes.

Abnormal pelvic morphology and high cervical length are responsible for high-risk pregnancies in women displaying achondroplasia.

Pregnancies of women displaying achondroplasia are at high risk of adverse events. Early sonographic assessment of affected women can indicate an unusually long cervical length. It is the consequence of pathological anatomy of the pelvis. Thus, there is a foreseeable dystocia owing to cephalopelvic disproportion. Furthermore, this situation could also complicate cervical ripening prior to fetal extraction.

Lactate in Amniotic Fluid: Predictor of Labor Outcome in Oxytocin-Augmented Primiparas' Deliveries.

BACKGROUND: One of the major complications related to delivery is labor dystocia, or an arrested labor progress. Many dystocic deliveries end vaginally after administration of oxytocin, but a large numbers of women with labor dystocia will undergo a long and unsafe parturition. As a result of the exertion required in labor, the uterus produces lactate. The uterine production of lactate is mirrored by the level of lactate in amniotic fluid (AFL). OBJECTIVES: To evaluate whether the level of AFL, analysed in a sample of amniotic fluid collected vaginally at arrested labor when oxytocin was needed, could predict labor outcome in nulliparous deliveries. METHODS: A prospective multicentre study including 3000 healthy primiparous women all with a singleton pregnancy, gestational age 37 to 42 weeks and no maternal /fetal chronic and/or pregnancy-related conditions. A spontaneous onset of labor, regular contractions and cervical dilation ≥ 3 cm were required before the women were invited to take part in the study. RESULTS: AFL, analysed within 30 minutes before augmentation, provides information about delivery outcome. Sensitivity for an acute cesarean section according to high (≥10.1mmol/l) or low (< 10.1mmol/l) AFL values was 39.0% (95% CI; 27-50), specificity 90.3% (95% CI; 87-93) PPV 37.3% (95% CI; 27-48) and NPV was 91.0% (95% CI; 88-93). The overall percentage of correct predictions of delivery outcome when the AFL level was used was 83.7%. Deliveries with a high AFL-level correlated with delivery time >12h (p = 0.04), post-partum fever (>38°C, p = 0.01) and post-partum haemorrhage >1.5L (p = 0.04). CONCLUSION: The AFL is a good predictor of delivery outcome in arrested nulliparous deliveries. Low levels of AFL may support the decision to continue a prolonged vaginal labor by augmentation with oxytocin. A high level of AFL correlates with operative interventions and post-partum complications.

Recurrent shoulder dystocia: is it predictable?

OBJECTIVE: To examine the course and outcome of deliveries occurring in women who previously experienced shoulder dystocia. In addition, recurrent shoulder dystocia risk factors were assessed. METHODS: A retrospective cohort analysis comparing all singleton deliveries with and without shoulder dystocia in their preceding delivery was conducted. Independent predictors of recurrent shoulder dystocia were investigated using a multiple logistic regression model. RESULTS: Of the 201,422 deliveries included in the analysis, 307 occurred in women with a previous shoulder dystocia (0.015 %). Women with a history of shoulder dystocia were more likely to be older, experienced higher rates of gestational diabetes mellitus, polyhydramnios, prolonged second stage, operative delivery and macrosomia (>4000 g) in the following delivery. Previous shoulder dystocia was found to be an independent risk factor for recurrent shoulder dystocia (OR = 6.1, 95 % CI 3.2-11.8, p value <0.001) in the multivariable regression analysis. CONCLUSIONS: Shoulder dystocia is an independent risk factor for recurrent shoulder dystocia. Deliveries in women with a history of shoulder dystocia are characterized by higher rates of operative delivery, prolonged second stage of labor and macrosomia.

Dystocia in dromedary camels: Prevalence, forms, risks and hematobiochemical changes.

The objectives of this study were to investigate the prevalence of dystocia in camel herds, its forms in primi- and multipara, the risks to fetus and dam, and the associated hematobiochemical changes. A total of 1890 calvings were surveyed for the prevalence of dystocia. Cases with dystocia (n=107) were examined for causes and treated with traction, fetotomy or Cesarean section. Logistic regression was performed to identify risk factors. The dependent variables were the fetal and maternal mortality, while the independent variables were parity, duration of dystocia, causes of dystocia, and method of treatment. Blood samples were collected from all dystocia camels and six controls for hematology and concentrations of serum amyloid A (SAA), haptoglobin (Hp), estradiol-17ß (E2), progesterone (P4), total protein, albumin, calcium, phosphorus, magnesium, blood urea nitrogen (BUN), creatinine and aspartate aminotransferase (AST). The overall prevalence of dystocia was 8.6%. Risk of dystocia was higher in camels managed in an intensive system than in those in a free system (Odds ratio=1.9, P=0.0003) and higher in primipara than in multipara (Odds ratio 1.7, P=0.005). Abnormal posture was the most important cause of dystocia (51.4%). Uterine torsion was the second most important cause (23.4%) and was mainly observed in multipara (P=0.0006). Dystocia was linked to high fetal mortality (87.9%). A significant relationship was found between fetal death and duration of dystocia (Odds ratio=8.04, P=0.005). The percentage of dam mortality was 17.8%. Significant associations were detected between dam mortality rate and the duration of dystocia (Odds ratio=4.74, P=0.03) and fetal viability (Odds ratio=5.82, P=0.02). Increasing duration of dystocia was associated with significant increases in SAA, Hp, BUN and AST, but with decreases in E2 (P<0.05). After a transient period of elevation, the white blood cell and neutrophil counts decreased (P<0.05). In conclusion, abnormal posture and uterine torsion were found to be the common causes of dystocia in dromedary camels, and fetal and maternal deaths were mainly associated with the duration of dystocia.

Effect of dystocia on subsequent reproductive performance and functional longevity in Holstein cows.

The objective of this study was to evaluate the effect of dystocia on the reproductive performance and functional longevity in Iranian Holsteins. Data consisted of 1 467 064 lactation records of 581 421 Holstein cows from 3083 herds which were collected by the Animal Breeding Center of Iran from April 1987 to February 2014. Reproduction traits in this study included interval from first to second calving, days open and days from first calving to first service. The generalized linear model was used for the statistical analysis of reproductive traits. Survival analysis was performed using the Weibull proportional hazards models to analyse the impact of dystocia on functional longevity. The incidence of dystocia had an adverse effect on the reproductive performance of dairy cows. Therefore, reproductive traits deteriorated along with increase in dystocia score (p < 0.05). The culling risk was increased along with increase in the score of dystocia (p < 0.0001). The greatest culling risk was observed in primiparous cows, small herds and low-yielding cows (p < 0.0001). Also, the lowest culling risk was found for cows calving at the youngest age (<27 months), and cows with age at first calving >33 months had the greatest risk (p < 0.0001). The results of current study indicated that dystocia had important negative effects on the reproductive performance and functional longevity in dairy cows, and it should be avoided as much as possible to provide a good perspective in the scope of economic and animal welfare issues in dairy herds.

Risk factors for brachial plexus injury in a large cohort with shoulder dystocia.

OBJECTIVE: To examine birthweight and other predictors of brachial plexus injury (BPI) among births complicated by shoulder dystocia. STUDY DESIGN: A retrospective cohort study of term births complicated by shoulder dystocia in California between 1997 and 2006. Birthweight at time of delivery was stratified into 500-g intervals. Women were further stratified by diabetes status, parity, and race/ethnicity. The perinatal outcome of BPI was assessed. RESULTS: This study included 62,762 deliveries complicated by shoulder dystocia, of which 3168 (5 %) resulted in BPI. The association between birthweight and BPI remained significant regardless of confounders. Each increasing birthweight interval was associated with an increasing risk of BPI compared with 3000-3499-g birthweight. Race/ethnicity, diabetes, and parity were also independently associated with BPI. CONCLUSION: Increasing birthweight increases the risk of BPI among births with shoulder dystocia, independent of advanced maternal age, race, parity, gestational diabetes, or operative vaginal delivery.

Clinical utility of calf front hoof circumference and maternal intrapelvic area in predicting dystocia in 103 late gestation Holstein-Friesian heifers and cows.

The objective of this study was to determine the clinical utility of measuring calf front hoof circumference, maternal intrapelvic area, and selected morphometric values in predicting dystocia in dairy cattle. An observational study using a convenience sample of 103 late-gestation Holstein-Friesian heifers and cows was performed. Intrapelvic height and width of the dam were measured using a pelvimeter, and the intrapelvic area was calculated. Calf front hoof circumference and birth weight were also measured. Data were analyzed using Spearman's correlation coefficient (rs), Mann-Whitney U test, and binary or ordered logistic regression; P < 0.05 was significant. The calving difficulty score (1-5) was greater in heifers (median, 3.0) than in cows (median, 1.0). Median intrapelvic area immediately before parturition was smaller in heifers (268 cm(2)) than in cows (332 cm(2)), whereas front hoof circumference and birth weight of the calf were similar in both groups. The calving difficulty score was positively associated with calf birth weight in heifers (rs = 0.39) and cows (rs = 0.24). Binary logistic regression using both dam and calf data indicated that the ratio of front hoof circumference of the calf to the maternal intrapelvic area provided the best predictor of dystocia (calving difficulty score = 4 or 5), with sensitivity = 0.50 and specificity = 0.93 at the optimal cutpoint for the ratio (>0.068 cm/cm(2)). Determining the ratio of calf front hoof circumference to maternal intrapelvic area has clinical utility in predicting the calving difficulty score in Holstein-Friesian cattle.

Stillbirth in dairy calves is influenced independently by dystocia and body shape.

The objectives of this study were to determine (1) if stillborn calves born following dystocia present with specific injuries/pathological changes compared to stillborns delivered without difficulty, and (2) whether such stillborns differ in conformation from dystocic calves that survive. Post-mortem examinations were carried out on 20 stillborns that were either unassisted (N) or were 'farm-staff'-assisted/normally presented (FN) at birth. Evidence of greater trauma and bruising was observed in the FN calves and parameters such as body length, birth-weight and thyroid:body weight were similar. In a second part of the study birth-weight, body length and height, girth length, body mass (BMI), and ponderal (PI) indices were assessed in 490 calves. Regardless of the severity of dystocia, stillborns had greater body lengths and lower BMIs and PIs than calves born alive (P<0.05), suggesting prenatal factors contribute to their post-natal survival. FN calves were heavier than N calves (P<0.05), and both FN and farm-staff-assisted/malpresented calves had lower PIs than N calves (P<0.05). The study found that criteria such as grossly visible carcass haemorrhage, bruising, and brain congestion were not reliable in terms of identifying calves that had experienced dystocia. Half of the stillborns had breathed indicating they were alive and possibly had experienced pain/distress at time of delivery. Body conformation was related to stillbirth independently of dystocia, a finding likely reflecting inadequate prenatal development.

Uterine dysfunction in biglycan and decorin deficient mice leads to dystocia during parturition.

Cesarean birth rates are rising. Uterine dysfunction, the exact mechanism of which is unknown, is a common indication for Cesarean delivery. Biglycan and decorin are two small leucine-rich proteoglycans expressed in the extracellular matrix of reproductive tissues and muscle. Mice deficient in biglycan display a mild muscular dystrophy, and, along with mice deficient in decorin, are models of Ehlers-Danlos Syndrome, a connective tissue anomaly associated with uterine rupture. As a variant of Ehlers-Danlos Syndrome is caused by a genetic mutation resulting in abnormal biglycan and decorin secretion, we hypothesized that biglycan and decorin play a role in uterine function. Thus, we assessed wild-type, biglycan, decorin and double knockout pregnancies for timing of birth and uterine function. Uteri were harvested at embryonic days 12, 15 and 18. Nonpregnant uterine samples of the same genotypes were assessed for tissue failure rate and spontaneous and oxytocin-induced contractility. We discovered that biglycan/decorin mixed double-knockout dams displayed dystocia, were at increased risk of delayed labor onset, and showed increased tissue failure in a predominantly decorin-dependent manner. In vitro spontaneous uterine contractile amplitude and oxytocin-induced contractile force were decreased in all biglycan and decorin knockout genotypes compared to wild-type. Notably, we found no significant compensation between biglycan and decorin using quantitative real time PCR or immunohistochemistry. We conclude that the biglycan/decorin mixed double knockout mouse is a model of dystocia and delayed labor onset. Moreover, decorin is necessary for uterine function in a dose-dependent manner, while biglycan exhibits partial compensatory mechanisms in vivo. Thus, this model is poised for use as a model for testing novel targets for preventive or therapeutic manipulation of uterine dysfunction.

Assessment of calving progress and reference times for obstetric intervention during dystocia in Holstein dairy cows.

The objectives of this observational study were (1) to assess the time from the appearance of the amniotic sac (AS) or feet outside the vulva to birth in Holstein cows (primiparous and multiparous) with (dystocia) or without assistance (eutocia) at calving, and (2) to estimate reference times to be used as guidelines for obstetric intervention in Holstein cows that need assistance during difficult births. Cows (n=92) from 1 commercial dairy operation were used in this study. Periparturient dairy cows (primiparous, n=58; multiparous, n=34) were placed in a maternity pen and constantly monitored until birth. The calving ease of cows, time from AS or feet appearance to birth, calving progress from a subset of 15 cows (frequency and duration of abdominal contractions during labor), calf birth weight, calf sex, and stillbirths (born dead or died within 24h after birth) were recorded. The reference times for obstetric intervention during dystocia were estimated based on values from unassisted births (normal). The normal range of times from the appearance of AS or feet outside the vulva to birth was estimated based on the mean+2 standard deviations (SD) of unassisted births. According to farm protocol, assistance was provided to cows without calving progress 80 min after AS appearance or earlier (e.g., to correct malpositions). Cows with dystocic births had a longer time from AS appearance to birth and increased incidence of stillbirth compared with cows with eutocic calvings. After the appearance of the AS, calving progress was evident every 15 min for eutocic births. The estimated reference times (mean+2 SD) from AS appearance to birth were 69.7 min and from feet appearance to birth were 64.6 min for eutocic births. Findings from this study suggested that calving personnel should start assisting cows 70 min after AS appearance (or 65 min after feet appearance) outside the vulva. The time spent in labor (straining) combined with the time from the appearance of the AS or feet to birth, and the assessment of calving progress (as described for eutocic births) should be used as guidelines for obstetric intervention during difficult births under field conditions. These reference times should be interpreted in combination with adequate obstetrical knowledge and examination.

Severe shoulder dystocia leading to neonatal injury: a case control study.

BACKGROUND AND OBJECTIVES: Severe shoulder dystocia (SD) is associated with neonatal brachial plexus injuries and skeletal fractures, with the former being the commonest cause for litigation related to birth trauma. The aim of this case-control study was to evaluate risk factors for birth injuries in cases presenting with SD. METHODS: Between January 2000 and December 2006, 22 babies who sustained brachial nerve paralysis or skeletal fractures following severe SD and requiring admission to Special Care Baby Unit (SCBU) were identified. The control group (n = 22) comprised the next infant delivered who was deemed to have SD but did not suffer significant birth injuries. Antenatal, labour and postnatal data were collected and compared between the two groups. RESULTS: The study and control groups had similar median maternal age (28 vs. 26.5 years), gestational age at delivery (40 vs. 40 weeks) and estimated blood loss (300 vs. 225 ml) (both P > 0.05, Mann-Whitney test). Median 1 min Apgar scores (5.5 vs. 7), maternal BMI (31.34 vs. 27.19 kg/m(2)) and duration of second stages (53.8 vs. 49.2 min) were also statistically similar in both groups (P > 0.05). However, compared to controls, brachial nerve injuries and skeletal fractures were more likely to occur in mothers with gestational diabetes (5/22 vs. 1/22) or who had previous big babies (4/22 vs. 1/22) (both P < 0.05, Fisher's exact test). Babies who had birth injuries were also more likely to have greater median birth weights (4.3 vs. 3.8 kg) and postnatal anthropometric measurements such as head circumference (35 vs. 34 cm) and ponderal indices (81.9 vs. 74.3 kg/m(3)) compared to controls. CONCLUSION: In babies with SD, brachial nerve injuries and skeletal fractures are more likely to occur in those with greater birthweights but also larger length to weight ratios. In these babies, assessment of abdominal circumference and biacromial length by magnetic resonance imaging (MRI) may help predict the likelihood of severe SD, especially in mothers with identifiable risk factors. However, further research in larger controlled trials are still needed to determine their predictive value.

Bladder stone: uncommon cause of mechanical dystocia.

Bladder stone can exceptionally cause an obstetrical dystocia. A combined procedure of cesarean section with a cystolithotomy is the most advocated attitude. The authors reported a rare case of mechanical dystocia caused by a bladder stone in a 27 year-old multiparous women. The diagnosis was suspected during labor and a vaginal examination revealed a large firm mass in the anterior vagina wall. This mass was responsible for an obstruction of the pelvis requiring a cesarean section. A cystotomy was performed intraoperatively and a bladder stone weighing 130 g and measuring 8 x 6 x 4 cm(3) was extracted. The postoperative course was uneventful.

Maternal morbidity associated with obstetrical maneuvers in shoulder dystocia.

OBJECTIVES: To determine whether shoulder dystocia and obstetrical maneuvers used for its relief have detrimental effects on perineum or immediate postpartum outcome. DESIGN: Case-control study. SETTING: Tertiary maternity ward in Marseille, France. POPULATION: A total 140 cases with shoulder dystocia and 280 controls without shoulder dystocia were enrolled by reviewing charts for the period between January 1999 and December 2004. METHODS: Demographic data including obstetrical history, age, height, weight before pregnancy and at the time of delivery, and respective body mass index (BMI) and obstetrical data including analgesic technique, duration of first and second stage of labor were compared in function of outcome and of the type and number of maneuvers used to relieve shoulder dystocia. RESULTS: Resolving shoulder dystocia required one obstetrical maneuver in 41 cases (29.3%) and two obstetrical maneuvers in 48 cases (34.3%). Third-degree tears occurred in one patient in the case group versus five in the control group. No correlation was found between the number of obstetrical maneuvers needed to relieve shoulder dystocia and risk for third-degree tear (OR: 0.8; 95% CI: 0.1-7.6). Mean hemoglobin values were 96.1 g/l in the case group and 96.0 g/l in the control group (p=0.95). There was no difference between the two groups regarding duration of postpartum hospitalization. The incidence of urinary incontinence was similar in the group that underwent obstetrical maneuvers: 4.7% (6/127) and in the control group: 3.7% (13/352). Only two patients reported de novo anal symptoms, both in the control group. CONCLUSION: Shoulder dystocia and obstetrical techniques used for its relief did not result in adverse maternal outcome.

Delivery of the macrosomic infant: cesarean section versus vaginal delivery.

The macrosomic fetus of a diabetic woman faces increased risk for injury at the time of birth. Cesarean section offers the potential for avoiding trauma to the fetus, but can result in increased morbidity in the mother as compared to vaginal delivery. In this article, the advantages and disadvantages of the 2 routes of delivery for the overgrown fetus of a diabetic mother are discussed. In addition, methods for diagnosing macrosomia by ultrasound are examined, along with the benefits and pitfalls of ultrasonic fetal weight estimation in the setting of diabetes. Finally, management approaches for selecting route of delivery for the macrosomic fetus are described and analyzed.

MR imaging pelvimetry: a useful adjunct in the treatment of women at risk for dystocia?

OBJECTIVE: The objective of this study was to test the clinical value of MR imaging for diagnosing cephalopelvic disproportion and for predicting labor outcome in women at risk for dystocia. SUBJECTS AND METHODS: Antepartum fetal sonography and maternal MR imaging pelvimetry measurements were performed at term in 38 pregnant women at risk for dystocia with a single fetus in cephalic presentation. Various methods used to diagnose cephalopelvic disproportion were evaluated in a blinded manner for their accuracy to predict both the presence of cephalopelvic disproportion and the mode of delivery (vaginal vs cesarean). RESULTS: None of the methods tested yielded both high sensitivity (15-100%) and high specificity (24-92%) for determining the presence of cephalopelvic disproportion and high levels of accuracy for predicting labor outcome (overall predictability, 50-74%). CONCLUSION: To achieve increased reliability of MR imaging pelvimetry in the diagnosis and treatment of dystocia and in predicting labor outcome, new methods assessing fetal-pelvic compatibility, including measurements of the pelvic outlet and the shape and configuration of the pelvis, need to be established and prospectively tested before firm recommendations for clinical use can be made.

Pelvimetry by magnetic resonance imaging as a diagnostic tool to evaluate dystocia.

OBJECTIVE: To test the clinical value of magnetic resonance imaging (MRI) pelvimetry for the diagnosis of cephalopelvic disproportion. METHODS: All deliveries from January 1993 through December 1994 were reviewed to identify 42 nulliparas at term with vertex presentation and cesarean delivery due to dystocia. Complete data were available for 41 women, and subjects were divided into the following two subgroups, according to clinical data: "cephalopelvic disproportion" (n = 28) and "failure to progress" (n = 13). Ten nulliparous women with uncomplicated vaginal delivery served as controls. Pelvimetry data from postpartum MRI were correlated with fetal and neonatal dimensions to evaluate various criteria for the diagnosis of cephalopelvic disproportion. RESULTS: Comparing both the fetal head volume derived from antepartum ultrasound assessment and the neonatal head volume (postpartum measurement) with maternal pelvic capacity determined by MRI, cephalopelvic disproportion (head volume exceeding pelvic capacity) indicated that 25 and 27, respectively, of the 28 women had been clinically diagnosed correctly with cephalopelvic disproportion, corresponding to sensitivities of 89% and 96%, respectively. Fetal head volume was not larger than pelvic capacity in any of the women in the control group. In seven of the 13 women diagnosed as "failure to progress," the fetal head volume exceeded the pelvic capacity. CONCLUSION: A fetal head volume estimate exceeding MRI-measured pelvic capacity is a frequent finding in nulliparas with cesarean birth due to cephalopelvic disproportion. An appropriate prospective study to determine the benefits of an antepartum diagnosis of cephalopelvic disproportion in high-risk nulliparas is warranted.