Mode of Delivery in Antepartum Singleton Stillbirths and Associated Risk Factors

OBJECTIVE

 This study was aimed to investigate delivery management of patients with antepartum stillbirth.

STUDY DESIGN

 Using data from fetal death certificates and linked maternal hospital discharge records, we identified a population-based sample of patients with singleton antepartum stillbirth at 20 to 42 weeks of gestation in California in 2007 to 2011. Primary outcomes were intended mode of delivery and actual mode of delivery. We used multivariable regressions to examine the association between patient demographic, clinical, and hospital characteristics and their mode of delivery. Separate analysis was performed for patients who had prior cesarean delivery versus those who did not.

RESULTS

 Of 7,813 patients with singleton antepartum stillbirth, 1,356 had prior cesarean, while 6,457 had no prior cesarean. Labor was attempted in 51.8% of patients with prior cesarean and 93.7% of patients without prior cesarean, with 76.2 and 95.8% of these patients, respectively, delivered vaginally. Overall, 18.9% of patients underwent a cesarean delivery (60.5% among those with prior cesarean and 10.2% among those without prior cesarean). Multivariable regression analysis identified several factors associated with the risk of cesarean delivery that were not medically indicated. For instance, among patients without prior cesarean, malpresentation (of which the vast majority was breech presentation) was associated with an increased likelihood of planned cesarean (adjusted odds ratio [OR] = 3.26, 95% confidence interval [CI]: 2.53-4.22) and cesarean delivery after attempting labor (adjusted OR = 3.09, 95% CI: 2.25-4.25). For both patients with and without prior cesarean, delivery at an urban teaching hospital was associated with a lower likelihood of planned cesarean and a lower likelihood of cesarean delivery after attempting labor (adjusted ORs ranged from 0.28 to 0.56, p < 0.001 for all).

CONCLUSION

 Over one in six patients with antepartum stillbirth underwent cesarean delivery. Among patients who attempted labor, rate of vaginal delivery was generally high, suggesting a potential opportunity to increase vaginal delivery in this population.

KEY POINTS

· In singleton antepartum stillbirths, 18.9% underwent cesarean delivery.. · Rate of vaginal delivery was high when labor was attempted.. · Both clinical and non-clinical factors were associated with risk of cesarean delivery..

Severe Maternal Morbidity Review and Preventability Assessment in a Large Academic Center

With the goal of identifying factors contributing to severe maternal morbidity (SMM) at our institution, we established a formal SMM review process. We performed a retrospective cohort study including all SMM cases as defined by American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine consensus criteria that were managed at Yale-New Haven Hospital over a 4-year period. Overall, 156 cases were reviewed. The SMM rate was 0.49% (95% CI 0.40-0.58). The leading causes of SMM were hemorrhage (44.9%) and nonintrauterine infection (14.1%). Two thirds of the cases were deemed to be preventable. Preventability was mostly associated with health care professional-level (79.4%) and system-level (58.8%) factors that could coexist. Detailed case review allowed for identification of preventable causes of SMM, revealed gaps in care, and allowed for implementation of practice changes targeting health care professional-level and system-level factors.

Racial and ethnic differences in severe maternal morbidity among singleton stillbirth deliveries

BACKGROUND

Despite growing evidence suggesting racial or ethnic disparities in the risk of severe maternal morbidity among live births, there is little research investigating potential differences in severe maternal morbidity risk among stillbirths across race and ethnicity.

OBJECTIVE

This study aimed to compare the risk of severe maternal morbidity by race and ethnicity among patients with singleton stillbirth pregnancies.

STUDY DESIGN

We used the California Linked Birth File database to perform a retrospective analysis of singleton stillbirth pregnancies delivered at 20 to 42 weeks' gestation between 2007 and 2011. The database contained information from fetal death certificates linked to maternal hospital discharge records. We defined severe maternal morbidity using the Centers for Disease Control and Prevention composite severe maternal morbidity indicator and compared rates of severe maternal morbidity across racial and ethnic groups. Multivariable regression analysis was used to examine how race and ethnicity were associated with severe maternal morbidity risk after accounting for the influence of patients' clinical risk factors, socioeconomic characteristics, and attributes of the delivery hospital.

RESULTS

Of the 9198 patients with singleton stillbirths, 533 (5.8%) experienced severe maternal morbidity. Non-Hispanic Black patients had a significantly higher risk of severe maternal morbidity (10.6% vs 5.2% in non-Hispanic White patients, 5.2% in Hispanic patients, and 5.1% in patients with other race or ethnicity; P<.001). The higher risk of severe maternal morbidity among non-Hispanic Black patients persisted even after adjusting for patients' clinical, socioeconomic, and hospital characteristics (adjusted odds ratio for non-Hispanic Black vs non-Hispanic White patients, 1.74; 95% confidence interval, 1.21-2.50). Further analysis separating blood-transfusion and nontransfusion severe maternal morbidity showed a higher risk of blood transfusion in non-Hispanic Black patients, which remained significant after adjusting for patients' clinical, socioeconomic, and hospital characteristics (adjusted odds ratio for non-Hispanic Black vs non-Hispanic White patients, 1.64; 95% confidence interval, 1.11-2.43). However, the higher risk of nontransfusion severe maternal morbidity in non-Hispanic Black patients was no longer significant after adjusting for patients' clinical risk factors (adjusted odds ratio for non-Hispanic Black vs non-Hispanic White patients, 1.38; 95% confidence interval, 0.83-2.30).

CONCLUSION

Severe maternal morbidity occurred in 5.8% of patients with a singleton stillbirth. Risk of severe maternal morbidity in stillbirth was higher in patients with non-Hispanic Black race, which was likely owing to a higher risk of hemorrhage, as evidenced by increased rate of blood transfusion.

Maternal respiratory SARS-CoV-2 infection in pregnancy is associated with a robust inflammatory response at the maternal-fetal interface

BACKGROUND

Pregnant women are at increased risk for severe outcomes from coronavirus disease 2019 (COVID-19), but the pathophysiology underlying this increased morbidity and its potential effect on the developing fetus is not well understood.

METHODS

We assessed placental histology, ACE2 expression, and viral and immune dynamics at the term placenta in pregnant women with and without respiratory severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

FINDINGS

The majority (13 of 15) of placentas analyzed had no detectable viral RNA. ACE2 was detected by immunohistochemistry in syncytiotrophoblast cells of the normal placenta during early pregnancy but was rarely seen in healthy placentas at full term, suggesting that low ACE2 expression may protect the term placenta from viral infection. Using immortalized cell lines and primary isolated placental cells, we found that cytotrophoblasts, the trophoblast stem cells and precursors to syncytiotrophoblasts, rather than syncytiotrophoblasts or Hofbauer cells, are most vulnerable to SARS-CoV-2 infection in vitro. To better understand potential immune mechanisms shielding placental cells from infection in vivo, we performed bulk and single-cell transcriptomics analyses and found that the maternal-fetal interface of SARS-CoV-2-infected women exhibited robust immune responses, including increased activation of natural killer (NK) and T cells, increased expression of interferon-related genes, as well as markers associated with pregnancy complications such as preeclampsia.

CONCLUSIONS

SARS-CoV-2 infection in late pregnancy is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion.

FUNDING

NIH (T32GM007205, F30HD093350, K23MH118999, R01AI157488, U01DA040588) and Fast Grant funding support from Emergent Ventures at the Mercatus Center.

SARS-CoV-2 infection in pregnancy is associated with robust inflammatory response at the maternal-fetal interface

Pregnant women appear to be at increased risk for severe outcomes associated with COVID-19, but the pathophysiology underlying this increased morbidity and its potential impact on the developing fetus is not well understood. In this study of pregnant women with and without COVID-19, we assessed viral and immune dynamics at the placenta during maternal SARS-CoV-2 infection. Amongst uninfected women, ACE2 was detected by immunohistochemistry in syncytiotrophoblast cells of the normal placenta during early pregnancy but was rarely seen in healthy placentas at full term. Term placentas from women infected with SARS-CoV-2, however, displayed a significant increase in ACE2 levels. Using immortalized cell lines and primary isolated placental cells, we determined the vulnerability of various placental cell types to direct infection by SARS-CoV-2 in vitro. Yet, despite the susceptibility of placental cells to SARS-CoV-2 infection, viral RNA was detected in the placentas of only a subset (~13%) of women in this cohort. Through single cell transcriptomic analyses, we found that the maternal-fetal interface of SARS-CoV-2-infected women exhibited markers associated with pregnancy complications, such as preeclampsia, and robust immune responses, including increased activation of placental NK and T cells and increased expression of interferon-related genes. Overall, this study suggests that SARS-CoV-2 is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion. While this likely represents a protective mechanism shielding the placenta from infection, inflammatory changes in the placenta may also contribute to poor pregnancy outcomes and thus warrant further investigation.

Coronary Disease in Pregnancy: Myocardial Infarction and Spontaneous Coronary Artery Dissection

Pregnancy-related maternal mortality and morbidity rates continue to increase in the United States despite global improvements in maternal outcomes. The unique hemodynamic and physiological changes of pregnancy results in a 3- to 4-fold increased risk of acute myocardial infarction (AMI) which causes a substantial proportion of all maternal cardiac deaths. In addition to atherosclerosis, pregnancy-associated AMI is commonly caused by nonatherosclerotic etiologies such as spontaneous coronary artery dissection, embolus to the coronary artery, and coronary vasospasm. Herein, the epidemiology, etiologies, presentation, diagnosis, and management of AMI in pregnancy is discussed along with future directions for multidisciplinary care.

Consolidation of obstetric services in a public health emergency

Though much of routine healthcare pauses in a public health emergency, childbirth continues uninterrupted. Crises like COVID-19 put incredible strains on healthcare systems and require strategic planning, flexible adaptability, clear communication, and judicious resource allocation. Experiences from obstetric units affected by COVID-19 highlight the importance of developing new teams and workflows to ensure patient and healthcare worker safety. Additionally, adapting a strategy that combines units and staff from different areas and hospitals can allow for synergistic opportunities to provision care appropriately to manage a structure and workforce at maximum capacity.

Coronavirus disease 2019 pregnancy outcomes in a racially and ethnically diverse population

Background

Older age and medical comorbidities are identified risk factors for developing severe coronavirus disease 2019. However, there are limited data on risk stratification, clinical and laboratory course, and optimal management of coronavirus disease 2019 in pregnancy.

Objective

Our study aimed to describe the clinical course of coronavirus disease 2019, effect of comorbidities on disease severity, laboratory trends, and pregnancy outcomes of symptomatic and asymptomatic severe acute respiratory syndrome coronavirus 2–positive pregnant women.

Study Design

This is a case series of pregnant and postpartum women who received positive test results for severe acute respiratory syndrome coronavirus 2 between March 3, 2020, and May 11, 2020, within 3 hospitals of the Yale New Haven Health delivery network. Charts were reviewed for basic sociodemographic and prepregnancy characteristics, coronavirus disease 2019 course, laboratory values, and pregnancy outcomes.

Results

Of the 1567 tested pregnant and postpartum women between March 3, 2020, and May 11, 2020, 9% (n=141) had a positive severe acute respiratory syndrome coronavirus 2 result. Hispanic women were overrepresented in the severe acute respiratory syndrome coronavirus 2–positive group (n=61; 43.8%). In addition, Hispanic ethnicity was associated with a higher rate of moderate and severe diseases than non-Hispanic (18% [11/61] vs 3.8% [3/78], respectively; odds ratio, 5.5; 95% confidence interval, 1.46–20.7; P=.01). Of note, 44 women (31.2%) were asymptomatic, 37 of whom (26.2%) were diagnosed on universal screening upon admission for delivery. Moreover, 59% (n=83) were diagnosed before delivery, 36% (n=51) upon presentation for childbirth, and 5% (n=7) after delivery. Severe disease was diagnosed in 6 cases (4.3%), and there was 1 maternal death. Obese women were more likely to develop moderate and severe diseases than nonobese women (16.4% [9/55] vs 3.8% [3/79]; odds ratio, 4.96; 95% confidence interval, 1.28–19.25; P=.02). Hypertensive disorders of pregnancy were diagnosed in 22.3% of women (17/77) who delivered after 20 weeks’ gestation. Higher levels of C-reactive protein during antepartum coronavirus disease 2019–related admission were more common in women with worse clinical course; however, this association did not reach statistical significance.

Conclusion

Coronavirus disease 2019 in pregnancy may result in severe disease and death. Hispanic women were more likely to receive a positive test result for severe acute respiratory syndrome 2 than other ethnic groups. Obesity and Hispanic ethnicity represent risk factors for moderate and severe diseases.

SARS-CoV-2 infection of the placenta

BACKGROUNDThe effects of the novel coronavirus disease 2019 (COVID-19) in pregnancy remain relatively unknown. We present a case of second trimester pregnancy with symptomatic COVID-19 complicated by severe preeclampsia and placental abruption.METHODSWe analyzed the placenta for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through molecular and immunohistochemical assays and by and electron microscopy and measured the maternal antibody response in the blood to this infection.RESULTSSARS-CoV-2 localized predominantly to syncytiotrophoblast cells at the materno-fetal interface of the placenta. Histological examination of the placenta revealed a dense macrophage infiltrate, but no evidence for the vasculopathy typically associated with preeclampsia.CONCLUSIONThis case demonstrates SARS-CoV-2 invasion of the placenta, highlighting the potential for severe morbidity among pregnant women with COVID-19.FUNDINGBeatrice Kleinberg Neuwirth Fund and Fast Grant Emergent Ventures funding from the Mercatus Center at George Mason University. The funding bodies did not have roles in the design of the study or data collection, analysis, and interpretation and played no role in writing the manuscript.

Prevalence of SARS-CoV-2 Among Patients Admitted for Childbirth in Southern Connecticut

This study describes the prevalence of positive SARS-CoV-2 test results among asymptomatic pregnant women presenting for labor and delivery at Yale New Haven health system hospitals.

Severe maternal morbidity during delivery hospitalisation in a large international administrative database, 2008-2013: a retrospective cohort

OBJECTIVE

This study utilized the Dr. Foster Global Comparators database to identify pregnancy complications and associated risk factors that led to severe maternal morbidity during delivery hospitalisations in large university hospitals based in the USA, Australia, and England.

DESIGN

Retrospective cohort.

SETTING

Births in the USA, England and Australia from 2008 to 2013.

SAMPLE

Data from delivery hospitalisations between 2008 and 2013 were examined using the Dr. Foster Global Comparators database.

METHODS

We identified delivery hospitalisations with life-threatening diagnoses or use of life-saving procedures, using algorithms for severe maternal morbidity from the Center for Disease Control. Frequency of severe maternal morbidity was calculated for each country.

MAIN OUTCOME MEASURES

Multivariable analysis was used to examine the association between morbidity and socio-demographic and clinical characteristics within each country. Chi-square tests assessed differences in covariates between countries.

RESULTS

From 2008 to 2013, there were 516 781 deliveries from a total of 18 hospitals: 24.5% from the USA, 57.0% from England and 18.4% from Australia. Overall severe maternal morbidity rate was 8.2 per 1000 deliveries: 15.6 in the USA, 5.0 in England, and 8.2 in Australia. The most common codes identifying severe morbidity included transfusion, disseminated intravascular coagulation, acute renal failure, cardiac events/procedures, ventilation, hysterectomy, and eclampsia. Advanced maternal age, hypertension, diabetes, and substance abuse were associated with severe maternal morbidity in all three countries.

CONCLUSION

Rates of severe maternal morbidity differed by country. Identification of geographical, socio-demographic, and clinical differences can help target modifications of practice and potentially reduce severe maternal morbidity.

TWEETABLE ABSTRACT

Rates of severe maternal morbidity vary, but risk factors associated with adverse outcomes are similar in developed countries.

Optimal maternal and neonatal outcomes and associated hospital characteristics

BACKGROUND

This study aims to examine hospital variation in both maternal and neonatal morbidities and identify institutional characteristics associated with hospital performance in a combined measure of maternal and neonatal outcomes.

METHODS

Using the California Linked Birth File containing data from birth certificate and hospital discharge records, we identified 1 322 713 term births delivered at 248 hospitals during 2010-2012. For each hospital, a risk-standardized rate of severe maternal morbidities and a risk-standardized rate of severe newborn morbidities were calculated after adjusting for patient clinical risk factors. Hospitals were ranked based on combined information on their maternal and newborn morbidity rates.

RESULTS

Risk-standardized severe maternal and severe newborn morbidity rates varied substantially across hospitals (10th to 90th percentile range = 67.5-148.2 and 141.8-508.0 per 10 000 term births, respectively), although there was no significant association between the two (P = 0.15). Government hospitals (non-Federal) were more likely than other hospitals to be in worse rank quartiles (P value for trend = 0.004), whereas larger volume was associated with better rank among hospitals in the first three quartiles (P = 0.004). The most prevalent morbidities that differed progressively across hospital rank quartiles were severe hemorrhage, disseminated intravascular coagulation, and heart failure during procedure/surgery for mothers, and severe infection, respiratory complication, and shock/resuscitation for neonates.

CONCLUSIONS

Hospitals with low maternal morbidity rates may not have low neonatal morbidity rates and vice versa, highlighting the importance of assessing joint maternal-newborn outcomes in order to fully characterize a hospital's obstetrical performance. Hospitals with smaller volume and government ownership tend to have less desirable outcomes and warrant additional attention in future quality improvement efforts.

Severe cardiovascular morbidity in women with hypertensive diseases during delivery hospitalization

BACKGROUND

Cardiovascular disease is the leading cause of pregnancy-related death in the United States. Identification of short-term indicators of cardiovascular morbidity has the potential to alter the course of this devastating disease among women. It has been established that hypertensive disorders of pregnancy are associated with increased risk of cardiovascular disease 10-30 years after delivery; however, little is known about the association of hypertensive disorders of pregnancy with cardiovascular morbidity during the delivery hospitalization.

OBJECTIVE

We aimed to identify the immediate risk of cardiovascular morbidity during the delivery hospitalization among women who experienced a hypertensive disorder of pregnancy.

MATERIALS AND METHODS

This retrospective cohort study of women, 15-55 years old with a singleton gestation between 2008 and 2012 in New York City, examined the risk of severe cardiovascular morbidity in women with hypertensive disorders of pregnancy compared with normotensive women during their delivery hospitalization. Women with a history of chronic hypertension, diabetes mellitus, or cardiovascular disease were excluded. Mortality and severe cardiovascular morbidity (myocardial infarction, cerebrovascular disease, acute heart failure, heart failure or arrest during labor or procedure, cardiomyopathy, cardiac arrest and ventricular fibrillation, or conversion of cardiac rhythm) during the delivery hospitalization were identified using birth certificates and discharge record coding. Using multivariable logistic regression, we assessed the association between hypertensive disorders of pregnancy and severe cardiovascular morbidity, adjusting for relevant sociodemographic and pregnancy-specific clinical risk factors.

RESULTS

A total of 569,900 women met inclusion criteria. Of those women, 39,624 (6.9%) had a hypertensive disorder of pregnancy: 11,301 (1.9%) gestational hypertension; 16,117 (2.8%) preeclampsia without severe features; and 12,206 (2.1%) preeclampsia with severe features, of whom 319 (0.06%) had eclampsia. Among women with a hypertensive disorder of pregnancy, 431 experienced severe cardiovascular morbidity (10.9 per 1000 deliveries; 95% confidence interval, 9.9-11.9). Among normotensive women, 1780 women experienced severe cardiovascular morbidity (3.4 per 1000 deliveries; 95% confidence interval, 3.2-3.5). Compared with normotensive women, there was a progressively increased risk of cardiovascular morbidity with gestational hypertension (adjusted odds ratio, 1.18; 95% confidence interval, 0.92-1.52), preeclampsia without severe features (adjusted odds ratio, 1.96; 95% confidence interval, 1.66-2.32), preeclampsia with severe features (adjusted odds ratio, 3.46; 95% confidence interval, 2.99-4.00), and eclampsia (adjusted odds ratio, 12.46; 95% confidence interval, 7.69-20.22). Of the 39,624 women with hypertensive disorders of pregnancy, there were 15 maternal deaths, 14 of which involved 1 or more cases of severe cardiovascular morbidity.

CONCLUSION

Hypertensive disorders of pregnancy, particularly preeclampsia with severe features and eclampsia, are significantly associated with cardiovascular morbidity during the delivery hospitalization. Increased vigilance, including diligent screening for cardiac pathology in patients with hypertensive disorders of pregnancy, may lead to decreased morbidity for mothers.

Hospital variation in utilization and success of trial of labor after a prior cesarean

BACKGROUND

Trial of labor after cesarean delivery is an effective and safe option for women without contraindications.

OBJECTIVES

The objective of the study was to examine hospital variation in utilization and success of trial of labor after cesarean delivery and identify associated institutional characteristics and patient outcomes.

STUDY DESIGN

Using linked maternal and newborn hospital discharge records and birth certificate data in 2010-2012 from the state of California, we identified 146,185 term singleton mothers with 1 prior cesarean delivery and no congenital anomalies or clear contraindications for trial of labor at 249 hospitals. Risk-standardized utilization and success rates of trial of labor after cesarean delivery were estimated for each hospital after accounting for differences in patient case mix. Risk for severe maternal and newborn morbidities, as well as maternal and newborn length of stay, were compared between hospitals with high utilization and high success rates of trial of labor after cesarean delivery and other hospitals. Bivariate analysis was also conducted to examine the association of various institutional characteristics with hospitals' utilization and success rates of trial of labor after cesarean delivery.

RESULTS

In the overall sample, 12.5% of women delivered vaginally. After adjusting for patient clinical risk factors, utilization and success rates of trial of labor after cesarean delivery varied considerably across hospitals, with a median of 35.2% (10th to 90th percentile range: 10.2-67.1%) and 40.5% (10th to 90th percentile range: 8.5-81.1%), respectively. Risk-standardized utilization and success rates of trial of labor after cesarean delivery demonstrated an inverted U-shaped relationship such that low or excessively high use of trial of labor after cesarean delivery was associated with lower success rate. Compared with other births, those delivered at hospitals with above-the-median utilization and success rates of trial of labor after cesarean delivery had a higher risk for uterine rupture (adjusted risk ratio, 2.74, P < .001), severe newborn respiratory complications (adjusted risk ratio, 1.46, P < .001), and severe newborn neurological complications/trauma (adjusted risk ratio, 2.48, P < .001), but they had a lower risk for severe newborn infection (adjusted risk ratio, 0.80, P = .003) and overall severe unexpected newborn complications (adjusted risk ratio, 0.86, P < .001) as well as shorter length of stays (adjusted mean ratio, 0.948 for mothers and 0.924 for newborns, P < .001 for both). Teaching status, system affiliation, larger volume, higher neonatal care capacity, anesthesia availability, higher proportion of midwife-attended births, and lower proportion of Medicaid or uninsured patients were positively associated with both utilization and success of trial of labor after cesarean delivery. However, rural location and higher local malpractice insurance premium were negatively associated with the utilization of trial of labor after cesarean delivery, whereas for-profit ownership was associated with lower success rate.

CONCLUSION

Utilization and success rates of trial of labor after cesarean delivery varied considerably across hospitals. Strategies to promote vaginal birth should be tailored to hospital needs and characteristics (eg, increase availability of trial of labor after cesarean delivery at hospitals with low utilization rates while being more selective at hospitals with high utilization rates, and targeted support for lower capacity hospitals).

Postpartum anticoagulation in women with mechanical heart valves

Background

Women with mechanical heart valves (MHV) requiring anticoagulation (AC) are at high risk for hemorrhagic complications. Despite guidelines to manage antenatal and peripartum AC, there are few evidence-based recommendations to guide the initiation of postpartum AC. We reviewed our institutional experience of pregnant women with MHV to lay the groundwork for recommendations of immediate postpartum AC therapy.

Study design

This descriptive retrospective cohort used ICD-9 and -10 codes to identify pregnant women with MHV on AC at the Yale-New Haven Hospital from 2007 to 2018. All identified patients were confirmed by chart review. Delivery hospitalization and the immediate postpartum AC management were reviewed. Maternal complications recorded were postpartum hemorrhage, transfusion, wound hematoma, intra-abdominal bleeding, stroke, valve thrombosis, and death. Further, immediate neonatal outcomes were detailed.

Results

Forty-two pregnant women with nonnative heart valves were identified during the study period. From those pregnant women, nine had an MHV and were anticoagulated throughout gestation. Of 19 total pregnancies, 14 met the inclusion criteria. The median gestational age of the delivered pregnancies was early term (37w2d). Nine deliveries were via cesarean (64%). The median time to restart AC after birth was 6 hours. After six deliveries (43%), AC was initiated ≤6 hours postpartum. Hemorrhagic complications occurred in six cases (43%), including wound and intra-abdominal hematomas. Four cases (29%) required blood transfusion. No maternal strokes, thrombotic events, or deaths were recorded. Five (38.5%) neonates required admission to the neonatal intensive care unit.

Conclusion

MHV in pregnancy was rare but was associated with significant maternal morbidity, particularly postpartum hemorrhagic complications. We noted significant variability in the timing of restarting postpartum AC and in the selected agents. Pooled institutional data and an interdisciplinary approach are recommended to minimize competing risks and sequelae of valve thrombosis and obstetrical hemorrhage and, thereby, to optimize maternal outcomes and develop evidence-based guidelines for postpartum AC management.

Estimated Placental Volume and Gestational Age

OBJECTIVE

The objective of this study was to validate estimated placental volume (EPV) across a range of gestational ages (GAs).

STUDY DESIGN

Three hundred sixty-six patients from 2009 to 2011 received ultrasound scans between 11 + 0 and 38 + 6 weeks GA to assess EPV. An EPV versus GA best fit curve was generated and compared with published normative curves of EPV versus GA in a different population. A subanalysis was performed to explore the relationship between EPV and birth weight (BW).

RESULTS

Analysis of EPV versus GA revealed a parabolic curve with the following best fit equation: EPV = (0.372 GA - 0.00364 GA²)³. EPV was weakly correlated with BW, and patients with an EPV in the bottom 50th percentile had 2.42 times the odds of having a newborn with a BW in the bottom 50th percentile (95% confidence interval: 1.27-4.68). Microscopic evaluation of two placentas corresponding to the smallest EPV outliers revealed significant placental pathology.

CONCLUSION

Placental volume increases throughout gestation and follows a predictable parabolic curve, in agreement with the existing literature. Further validation is required, but EPV may have the potential for clinical utility as a screening tool in a variety of settings.

Analysis of telomere length in Dolly, a sheep derived by nuclear transfer

We have used a (TTAGGG) oligonucleotide probe to demonstrate that ovine telomeres are composed of (TTAGGG) repeat arrays and to compare the terminal restriction fragment lengths of sheep derived by natural mating and nuclear transfer. Here we show that ovine somatic telomeres decrease in length with age, and that Dolly, derived by the transfer of 6-year-old adult somatic nucleus, exhibits diminished terminal restriction fragment lengths. The decrease is consistent with the age of the donor tissue and telomere erosion during in vitro culture. Nuclear transfer does not restore telomere lengths. Dolly otherwise appears physiologically and phenotypically normal for her breed and age. We further report on apparent telomere lengthening in sheep, occurring during the first year in naturally derived lambs.

Comparative analysis of 2-D versus 3-D ultrasound estimation of the fetal adrenal gland volume and prediction of preterm birth

OBJECTIVE

We aim to test the hypothesis that two-dimensional (2-D) fetal adrenal gland volume (AGV) measurements offer similar volume estimates as volume calculations based on 3-D technique.

METHODS

Fetal AGV was estimated by three-dimensional (3-D) ultrasound (VOCAL) in 93 women with signs/symptoms of preterm labor and 73 controls. Fetal AGV was calculated using an ellipsoid formula derived from 2-D measurements of the same blocks (0.523 × length × width × depth). Comparisons were performed by intraclass correlation coefficient (ICC), coefficient of repeatability, and Bland-Altman method. The corrected AGV (cAGV; AGV/fetal weight) was calculated for both methods and compared for prediction of preterm birth (PTB) within 7 days.

RESULTS

Among 168 volumes, there was a significant correlation between 3-D and 2-D methods (ICC = 0.979; 95% confidence interval [CI]: 0.971 to 0.984). The coefficient of repeatability for the 3-D was superior to the 2-D method (intraobserver 3-D: 30.8, 2-D:57.6; interobserver 3-D:12.2, 2-D: 15.6). Based on 2-D calculations, cAGV ≥ 433 mm3/kg was best for prediction of PTB (sensitivity: 75%, 95% CI = 59 to 87; specificity: 89%, 95% CI = 82 to 94). Sensitivity and specificity for the 3-D cAGV (cutoff ≥ 420 mm3/kg) was 85% (95% CI = 70 to 94) and 95% (95% CI = 90 to 98), respectively. In receiver-operating-curve curve analysis, 3-D cAGV was superior to 2-D cAGV for prediction of PTB (z = 1.99, p = 0.047).

CONCLUSION

2-D volume estimation of fetal adrenal gland using ellipsoid formula cannot replace 3-D AGV calculations for prediction of PTB.

Accreta complicating complete placenta previa is characterized by reduced systemic levels of vascular endothelial growth factor and by epithelial-to-mesenchymal transition of the invasive trophoblast

OBJECTIVE

We sought to characterize serum angiogenic factor profile of women with complete placenta previa and determine if invasive trophoblast differentiation characteristic of accreta, increta, or percreta shares features of epithelial-to-mesenchymal transition.

STUDY DESIGN

We analyzed gestational age-matched serum samples from 90 pregnant women with either complete placenta previa (n = 45) or uncomplicated pregnancies (n = 45). Vascular endothelial growth factor (VEGF), placental growth factor, and soluble form of fms-like-tyrosine-kinase-1 were immunoassayed. VEGF and phosphotyrosine immunoreactivity was surveyed in histological specimens relative to expression of vimentin and cytokeratin-7.

RESULTS

Women with previa and invasive placentation (accreta, n = 5; increta, n = 6; percreta, n = 2) had lower systemic VEGF (invasive previa: median 0.8 [0.02-3.4] vs control 6.5 [2.7-10.5] pg/mL, P = .02). VEGF and phosphotyrosine immunostaining predominated in the invasive extravillous trophoblasts that coexpressed vimentin and cytokeratin-7, an epithelial-to-mesenchymal transition feature and tumorlike cell phenotype.

CONCLUSION

Lower systemic free VEGF and a switch of the interstitial extravillous trophoblasts to a metastable cell phenotype characterize placenta previa with excessive myometrial invasion.

Cord blood erythropoietin and interleukin-6 for prediction of intraventricular hemorrhage in the preterm neonate

OBJECTIVE

To evaluate cord blood erythropoietin (EPO) and interleukin-6 (IL-6) levels to predict preterm infants at risk of developing intraventricular hemorrhage (IVH).

METHODS

Levels of umbilical cord EPO, acid-base status and IL-6 were analyzed in 116 consecutive, preterm newborns (GA at delivery: 29 [23-34 ] weeks) born to mothers who had a clinically indicated amniocentesis to rule out infection. Early-onset neonatal sepsis (EONS) was diagnosed using symptoms, hematological criteria and blood cultures.

RESULTS

IVH was diagnosed by cranial ultrasounds. The prevalence of IVH in our population was 25% (29/116). There was a direct relationship between cord blood EPO and cord blood IL-6 concentration (r = 0.225, p = 0.014), independent of GA at birth. Elevated cord blood EPO levels (r = 0.182, p = 0.016) and GA at birth (r =  -0.236, p = 0.004) remained significant independent factors associated with the risk of IVH, when evaluated with stepwise logistic regression analyses. Cord blood IL-6, pH, and EONS were not associated with IVH. These relationships remained following correction for GA at birth (p = 0.027).

CONCLUSIONS

Our results suggest that elevation in cord blood EPO may predict newborns at risk for IVH, independent of fetal inflammatory status. Further studies are warranted to confirm this association.

Cesarean scar ectopic pregnancy: case series and review of the literature

Cesarean scar ectopic pregnancy is becoming increasingly common at tertiary care hospitals around the world. It is a condition in which the embryo implants within the myometrium at the site of a previous cesarean hysterotomy, and it can occur in women with only one prior cesarean delivery. We present four cases of cesarean scar ectopic pregnancy diagnosed within a 6-month period between 2007 and 2008. Their initial presentations and management are discussed, followed by a review of the published literature summarizing both diagnostic and management recommendations.

Congenital heart defects in twin gestations

As ultrasound technology advances, diagnosis of fetal malformations, particularly congenital heart defects (CHD) is becoming standard practice. Currently, a key element of obstetrical care is the use of ultrasound to diagnose chorionicity in multiple gestations. Given the difference in incidence and types of complications between dichorionic and monochorionic pregnancies, early diagnosis of chorionicity is critical to determine the type of care and counseling a patient receives throughout the pregnancy. Early diagnosis of chorionicity allows investigators to more accurately determine the risk of CHD in monochorionic pregnancies. It has been long known that twin gestations incur a higher risk of congenital malformations, including CHD. However, it was not until recently that the incidence could be determined according to chorionicity. Previous studies looking at risk of malformations including CHD used the like-sex technique as a proxy for chorionicity, thereby overestimating the prevalence of monochorionic twins because roughly two-thirds of all twin gestations (including dichorionic) are the same sex. The rate of multiple gestations is increasing in the developed world. Assisted reproductive technology (ART) is partly responsible for the increased incidence of multiples. While many of the ART conceived pregnancies are dichorionic multiples, there is evidence that ART increases the risk of monochorionic multiple gestations. Presently, it is not technically feasible, nor practical, to screen all pregnancies with fetal echocardiography. Thus, many perinatal ultrasound centers screen women for risk factors that place them at higher risk for having a fetus with CHD. This higher risk' group then receives a fetal echocardiogram. The available literature regarding risk of CHD in monochorionic multiple gestations strongly points to a significant increase over the general population risk of 0.5-0.8%. Fetal echocardiography is technically feasible in twin pregnancies and increasingly available. Monochorionic multiple gestations should be screened with fetal echocardiography.

Independent activation of MAP kinase and MPF during the initiation of meiotic maturation in pig oocytes

Mitogen-activated protein (MAP) kinase is universally activated during oocyte maturation in all vertebrates studied to date. Its role in the resumption of meiosis and in the activation of maturation-promoting factor (MPF) remains unclear, especially in domestic species such as the pig. This study aimed to clarify the temporal and causal relationships between MAP kinase and MPF during meiotic maturation, particularly during the resumption of meiosis. Pig oocytes were matured synchronously in culture by treatment with cycloheximide. Kinase activities were analysed using a sensitive in vitro double-kinase assay and the specific MAP kinase pathway inhibitor U0126. MAP kinase and MPF were activated simultaneously at the time of germinal vesicle breakdown (GVBD; 6 h after removal of cycloheximide); they reached significant activity at 7 h (P < 0.05). The activities increased in parallel during GVBD (6-10 h) and peaked when the oocytes entered metaphase I (MI; 10 h). Whereas MAP kinase remained stable at peak activity thereafter, MPF activity significantly declined during the MI-MII transition (16-20 h) but increased to a second peak at MII (22 h). MAP kinase activity in denuded and cumulus-cell enclosed oocytes was completely inhibited by 20 and 80 mmicro mol U0126 l(-1), respectively. Oocytes without detectable MAP kinase activity underwent normal GVBD in terms of nuclear morphology and timing, although later meiotic stages were abnormal. The kinetics of MPF activity during GVBD were unaffected by U0126. This study has demonstrated that MAP kinase is activated simultaneously with MPF at GVBD, but that its activation is not essential for the activation of MPF nor for the resumption of the first meiosis in pig oocytes.

Nuclear transfer in practice

The technique of nuclear transfer (NT) allows the production of embryos, fetuses, and offspring from a range of embryonic, fetal, and adult derived cell types in a range of species. Successful development is dependent upon numerous factors, including type of recipient cell, source of recipient cell, method of reconstruction, activation, embryo culture, donor cell type, and donor and recipient cell cycle stages. The present review will discuss the uses of NT, the techniques presently available, and the factors affecting subsequent development.

Cloned pigs produced by nuclear transfer from adult somatic cells

Since the first report of live mammals produced by nuclear transfer from a cultured differentiated cell population in 1995 (ref. 1), successful development has been obtained in sheep, cattle, mice and goats using a variety of somatic cell types as nuclear donors. The methodology used for embryo reconstruction in each of these species is essentially similar: diploid donor nuclei have been transplanted into enucleated MII oocytes that are activated on, or after transfer. In sheep and goat pre-activated oocytes have also proved successful as cytoplast recipients. The reconstructed embryos are then cultured and selected embryos transferred to surrogate recipients for development to term. In pigs, nuclear transfer has been significantly less successful; a single piglet was reported after transfer of a blastomere nucleus from a four-cell embryo to an enucleated oocyte; however, no live offspring were obtained in studies using somatic cells such as diploid or mitotic fetal fibroblasts as nuclear donors. The development of embryos reconstructed by nuclear transfer is dependent upon a range of factors. Here we investigate some of these factors and report the successful production of cloned piglets from a cultured adult somatic cell population using a new nuclear transfer procedure.

Production of gene-targeted sheep by nuclear transfer from cultured somatic cells

It is over a decade since the first demonstration that mouse embryonic stem cells could be used to transfer a predetermined genetic modification to a whole animal. The extension of this technique to other mammalian species, particularly livestock, might bring numerous biomedical benefits, for example, ablation of xenoreactive transplantation antigens, inactivation of genes responsible for neuropathogenic disease and precise placement of transgenes designed to produce proteins for human therapy. Gene targeting has not yet been achieved in mammals other than mice, however, because functional embryonic stem cells have not been derived. Nuclear transfer from cultured somatic cells provides an alternative means of cell-mediated transgenesis. Here we describe efficient and reproducible gene targeting in fetal fibroblasts to place a therapeutic transgene at the ovine alpha1(I) procollagen (COL1A1) locus and the production of live sheep by nuclear transfer.

Nuclear transfer from somatic cells: applications in farm animal species

The reconstruction of mammalian embryos by transfer of a blastomere nucleus to an enucleated oocyte or zygote allows for the production of genetically identical individuals. This has advantages for research (that is, as biological controls) and commercial applications (that is, multiplication of genetically valuable livestock). However, the number of offspring that can be produced from a single embryo is limited both by the number of blastomeres (embryos at the 32-64-cell stage are the most widely used in farm animal species) and the limited efficiency of the nuclear transfer procedure. The ability to produce live offspring by nuclear transfer from cells that can be propagated and maintained in culture offers many advantages, including the production of many identical offspring over an extended period (since cultured cells can be frozen and stored indefinitely) and the ability to modify genetically or to select populations of cells of specific genotypes or phenotypes before embryo reconstruction. This objective has been achieved with the production of lambs using nuclei from cultured cells established from embryonic, fetal and adult material. In addition, lambs transgenic for human factor IX have been produced from fetal fibroblasts transfected and selected in culture.

Production of live calves derived from embryonic stem-like cells aggregated with tetraploid embryos

To date, cloned farm animals have been produced by nuclear transfer from embryonic, fetal, and adult cell types. However, mice completely derived from embryonic stem (ES) cells have been produced by aggregation with tetraploid embryos. The objective of the present study was to generate offspring completely derived from bovine ES-like cells. ES-like cells isolated from the inner cell mass of in vitro-produced embryos were aggregated with tetraploid bovine embryos generated by electrofusion at the 2-cell stage. A total of 77 embryo aggregates produced by coculture of two 8-cell-stage tetraploid embryos and a clump of ES-like cells were cultured in vitro. Twenty-eight of the aggregates developed to the blastocyst stage, and 12 of these were transferred to recipient cows. Six calves representing 2 singletons and 2 sets of twins were produced from the transfer of the chimeric embryos. Microsatellite analysis for the 6 calves demonstrated that one calf was chimeric in the hair roots and the another was chimeric in the liver. However, unfortunately, both of these calves died shortly after birth. Two of the placentae from the remaining pregnancies were also chimeric. These results indicate that the bovine ES-like cells used in these studies were able to contribute to development.

New advances in somatic cell nuclear transfer: application in transgenesis

The ability to produce live offspring by nuclear transfer from cultured somatic cells provides a route for the precise genetic manipulation of large animal species. Such modifications include the addition, or "knock-in", and the removal or inactivation, "knock-out", of genes or their control sequences. This paper will review some of the factors which affect the development of embryos produced by nuclear transfer, the advantages of using cultured cells as donors of genetic material, and methods that have been developed to enrich gene targeting frequency. Commercial applications of this technology in biomedicine and agriculture will also be addressed.

Embryonic and somatic cell cloning

Revolutionary opportunities in biology, medicine and agriculture arise from the observation that offspring are obtained after nuclear transfer if somatic donor cells are induced to become quiescent. Exploitation of many of these opportunities will depend upon optimizing procedures for nuclear transfer. This may come about through an understanding of the means by which factors in the oocyte cytoplasm act upon the DNA of the transferred nucleus to regulate gene expression. Similarly, research will extend the procedure to other species. This technology may be used for embryo production, the introduction of genetic change and the derivation of cells needed to treat human diseases. Groups of genetically identical animals will be used in research to control genetic variation and to allow transfer of cells between individuals. In agriculture, production of a small number of clones will separate genetic and environmental effects, whereas production of larger numbers of offspring will disseminate genetic improvement from nucleus herds. Precise genetic modification will be achieved by site specific recombination in the donor cells before nuclear transfer. In all mammals it will become possible to define the role of any gene product and to analyse the mechanisms that regulate gene expression. Medical uses of these techniques will include the production of proteins needed to treat disease and the supply of organs such as hearts, livers and kidneys from pigs. As genome mapping projects identify loci associated with traits of commercial importance in agriculture then gene targeting will be used to study this effect. Finally, cells capable of differentiation into any of the tissues of a patient will provide treatment for diseases reflecting damage to a specific cell population that neither repairs nor replaces itself.

Nuclear transfer in farm animal species

CLONE 'a group of two or more individuals with identical genetic makeup derived, by asexual reproduction, from a single common parent or ancestor' (The Chambers Dictionary 1993, Chambers Harrap). The term clone was originally applied to plants but has subsequently been used in a much broader context to include a person or thing closely similar to another, a copy or replica. In animals, true clones, as defined above, may be produced by embryo splitting or blastomere separation either artificially, or as occurs naturally in the production of identical twins. In these individuals all of the components making up the individual, including nuclear genetic material (the genome) and other maternally derived factors are derived from a single unique embryo which is the result of sexual reproduction. The term clone has been applied to animals produced by the technique of nuclear transfer. In this asexual process, nuclear genetic material is transferred from a donor cell (karyoplast) into a recipient cell (cytoplast) from which the genetic material has been removed. In farm animals the cytoplast of choice is the matured oocyte (or unfertilised egg) thus the animals developing from this technique are not true clones as each cytoplast is often derived from a different animal. The resultant animals may therefore be more aptly described as 'genomic copies'. In mammals, successful development of embryos reconstructed by nuclear transfer was originally restricted to using early embryos as nuclear donors, however, recent progress has demonstrated successful development using nuclei from embryonic, foetal and adult derived cell populations. Numerous factors affect the development of embryos reconstructed by nuclear transfer including; the cell cycle stage of the recipient cell, the cell cycle stage of the donor nucleus, the differentiated state of the donor nucleus, activation of the recipient cell, the culture method. In addition, there are variations in success between species, these may be related to differences in organisation of the cytoskeleton and/or the meiotic spindle in the recipient cell,differences in cell cycle control during early development, the onset of zygotic transcription or differences in the metabolic requirements of early embryos in vitro. The aim of this article is to describe and discuss some of these factors in relation to the successful development of nuclear transfer reconstructed embryos and in particular to the 'reprogramming' or 'remodeling' of the donor genetic material to attain successful development.

Nuclear Equivalence, Nuclear Transfer, and the Cell Cycle

The last 20 years have seen the development of techniques for the production of mammals by nuclear transfer. Originally limited to the swapping of pronuclei and the use of early cleavage-stage embryos as nuclear donors, nuclear transfer came of age in 1995 with the birth of 2 Welsh Mountain lambs, Megan and Morag, that were produced using cultured differentiated cells as donors of genetic material. In 1996, Dolly was the first animal to be produced using the genetic material from an adult-derived somatic cell. The techniques used in the production of these animals have now been reproduced in both sheep and cattle, and as predicted, successful development has been obtained using donor cells taken directly ex vivo. This article reviews the current status of mammalian nuclear transfer and the biological background to these successes.

Maintenance of bovine oocytes in meiotic arrest and subsequent development In vitro: A comparative evaluation of antral follicle culture with other methods

The frequency of development of bovine embryos produced by maturation, fertilization, and culture in vitro is lower than that observed in vivo. One factor that may affect both the frequency of development and the quality of the embryos produced is the developmental competence of the oocyte. In current in vitro production systems, oocyte maturation, characterized by the resumption of meiosis, occurs after oocyte aspiration from the follicle. The developmental competence of individual oocytes may be improved by inducing maturation after culturing under conditions that inhibit the resumption of meiosis. In order to test this hypothesis, a system has been established in which intact antral follicles (3-8 mm in diameter) are cultured in vitro. During this period the oocytes are maintained at the germinal vesicle (GV) stage under the inhibitory effects of the follicle. Culture of intact antral follicles was compared with two other "physiological" methods for the maintenance of GV arrest: oocytes were cultured attached to a small part of the follicle wall or within hemisections of follicles. It was found that 96.8% of oocytes recovered from intact antral follicles-as compared to 24.6% attached to a small part of the follicle wall and 62.7% within hemisections of follicles-were maintained at the GV stage after 24-h culture. The effects on GV arrest and subsequent maturation of the oocytes were evaluated after longer periods of antral follicle culture (2, 4, and 7 days). As the culture period increased, the number of GV-arrested oocytes decreased; the maximum percentage of GV arrest was observed after 24-h culture. The majority of these oocytes matured to metaphase II. A comparison of blastocyst production was made after fertilization and subsequent development of oocytes obtained following follicle culture and of control oocytes aspirated directly from antral follicles. The cleavage rate and percentage of blastocyst production in these two groups were 54.6 +/- 13.9%, 48.4 +/- 8.4% and 68.6 +/- 8.6%, 32.8 +/- 10.8%, respectively. Statistical analysis showed significant differences in both cleavage rate and blastocyst production between these two groups. Total cell numbers in the control group were 144.6 +/- 7.28 and 152.0 +/- 25.8 after follicle culture. It is concluded that culture of intact antral follicles for 24 h is an alternative method for the maintenance of bovine oocytes in meiotic arrest and that these oocytes acquire a greater developmental competence in vitro.

Human factor IX transgenic sheep produced by transfer of nuclei from transfected fetal fibroblasts

Ovine primary fetal fibroblasts were cotransfected with a neomycin resistance marker gene (neo) and a human coagulation factor IX genomic construct designed for expression of the encoded protein in sheep milk. Two cloned transfectants and a population of neomycin (G418)-resistant cells were used as donors for nuclear transfer to enucleated oocytes. Six transgenic lambs were liveborn: Three produced from cloned cells contained factor IX and neo transgenes, whereas three produced from the uncloned population contained the marker gene only. Somatic cells can therefore be subjected to genetic manipulation in vitro and produce viable animals by nuclear transfer. Production of transgenic sheep by nuclear transfer requires fewer than half the animals needed for pronuclear microinjection.

Viable offspring derived from fetal and adult mammalian cells

Fertilization of mammalian eggs is followed by successive cell divisions and progressive differentiation, first into the early embryo and subsequently into all of the cell types that make up the adult animal. Transfer of a single nucleus at a specific stage of development, to an enucleated unfertilized egg, provided an opportunity to investigate whether cellular differentiation to that stage involved irreversible genetic modification. The first offspring to develop from a differentiated cell were born after nuclear transfer from an embryo-derived cell line that had been induced to become quiescent. Using the same procedure, we now report the birth of live lambs from three new cell populations established from adult mammary gland, fetus and embryo. The fact that a lamb was derived from an adult cell confirms that differentiation of that cell did not involve the irreversible modification of genetic material required for development to term. The birth of lambs from differentiated fetal and adult cells also reinforces previous speculation that by inducing donor cells to become quiescent it will be possible to obtain normal development from a wide variety of differentiated cells.

Sheep cloned by nuclear transfer from a cultured cell line

Nuclear transfer has been used in mammals as both a valuable tool in embryological studies and as a method for the multiplication of 'elite' embryos. Offspring have only been reported when early embryos, or embryo-derived cells during primary culture, were used as nuclear donors. Here we provide the first report, to our knowledge, of live mammalian offspring following nuclear transfer from an established cell line. Lambs were born after cells derived from sheep embryos, which had been cultured for 6 to 13 passages, were induced to quiesce by serum starvation before transfer of their nuclei into enucleated oocytes. Induction of quiescence in the donor cells may modify the donor chromatin structure to help nuclear reprogramming and allow development. This approach will provide the same powerful opportunities for analysis and modification of gene function in livestock species that are available in the mouse through the use of embryonic stem cells.

Cell cycle co-ordination in embryo cloning by nuclear transfer

Exciting new opportunities in embryo cloning have been made possible by recent studies on the interaction of the donor nucleus with the recipient cytoplasm after embryo reconstruction. This article reviews information regarding the co-ordination of nuclear and cytoplasmic events during embryo reconstruction, in particular the direct and indirect effects of maturation/ meiosis/mitosis-promoting factor (MPF), upon the transferred nucleus. This will be discussed in relation to DNA replication, the maintenance of correct ploidy, the occurrence of chromosomal abnormalities and development of reconstructed embryos. Although this review is primarily concerned with the reconstruction of mammalian embryos, specific examples from amphibians will also be cited.

Isolation and characterization of permanent cell lines from inner cell mass cells of bovine blastocysts

Inner cell masses (ICM) from in vitro produced day 8 or 9 bovine blastocysts were isolated by immunosurgery and cultured under different conditions in order to establish which of two feeder cell types and culture media were most efficient in supporting attachment and outgrowth of the bovine ICM cells. The efficiency of attachment and outgrowth of the ICM cells could be markedly improved when STO feeder cells were used instead of bovine uterus epithelial cells, and by using charcoal-stripped serum instead of normal serum to supplement the culture medium. More than 20 stable cell lines were obtained. Some of these lines were examined by immunofluorescence for developmentally regulated markers. From these results we conclude that the cell lines resemble epithelial cells, rather than pluripotent ICM cells. The developmental potential of cells of one of the lines was tested in the nuclear transfer assay. The cell line could support the initial development of enucleated oocytes, but none of the reconstructed embryos passed the eight-cell block.

Transfer of nuclei from 8-cell stage mouse embryos following use of nocodazole to control the cell cycle

Mouse 2-, 4-, 8-, and 16-cell embryos were exposed to nocodazole in M16 culture medium. The effect of different concentrations and exposure times on the efficiency of cell cycle synchronization and the development of the treated embryos after release from the drug was determined. The minimum effective concentration (> 95% of arrested nuclei) for 4-, 8-, and 16-cell embryos was 5 microM nocodazole. The effect upon subsequent development of mouse embryos depended upon both the stage of development of the embryo at treatment (P < 0.001) and the length of exposure to nocodazole (P < 0.001). Exposure to any concentration of nocodazole within the range 2.5-10 microM for 12 hr caused a reduction in the proportion of embryos that formed blastocysts. As the period of exposure to 5 microM nocodazole increased from 12 to 24 hr, the proportion of embryos developing to the blastocyst stage decreased. The lower proportion of embryos developing to the blastocyst stage and to term (P < 0.01) suggests that the more advanced stages were more susceptible to damage as a result of exposure to nocodazole. The rate of development of 4-cell embryos to blastocysts was not affected when an exposure time of 9 hr was used. Together these results show that it is possible to use nocodazole to arrest mouse embryonic cells in mitosis but that it is not appropriate to culture the embryos in the presence of this drug for prolonged periods. Individual blastomeres completed mitosis at 60-90 min and started DNA synthesis at 120-150 min after release from nocodazole.(ABSTRACT TRUNCATED AT 250 WORDS)