Association of Parity and Previous Birth Outcome With Brachial Plexus Birth Injury Risk.

OBJECTIVE: To evaluate the association of maternal delivery history with a brachial plexus birth injury risk in subsequent deliveries and to estimate the effect of subsequent delivery method on brachial plexus birth injury risk. METHODS: We conducted a retrospective cohort study of all live-birth deliveries occurring in California-licensed hospitals from 1996 to 2012. The primary outcome was recurrent brachial plexus birth injury in a subsequent pregnancy. The exposure was delivery history (parity, shoulder dystocia in a previous delivery, or previously delivering a neonate with brachial plexus birth injury). Multiple logistic regression was used to model adjusted associations of delivery history with brachial plexus birth injury in a subsequent pregnancy. The adjusted risk and adjusted risk difference for brachial plexus birth injury between vaginal and cesarean deliveries in subsequent pregnancies were determined, stratified by delivery history, and the number of cesarean deliveries needed to prevent one brachial plexus birth injury was determined. RESULTS: Of 6,286,324 neonates delivered by 4,104,825 individuals, 7,762 (0.12%) were diagnosed with a brachial plexus birth injury. Higher parity was associated with a 5.7% decrease in brachial plexus birth injury risk with each subsequent delivery (adjusted odds ratio [aOR] 0.94, 95% CI 0.92-0.97). Shoulder dystocia or brachial plexus birth injury in a previous delivery was associated with fivefold (0.58% vs 0.11%, aOR 5.39, 95% CI 4.10-7.08) and 17-fold (1.58% vs 0.11%, aOR 17.22, 95% CI 13.31-22.27) increases in brachial plexus birth injury risk, respectively. Among individuals with a history of delivering a neonate with a brachial plexus birth injury, cesarean delivery was associated with a 73.0% decrease in brachial plexus birth injury risk (0.60% vs 2.21%, aOR 0.27, 95% CI 0.13-0.55) compared with an 87.9% decrease in brachial plexus birth injury risk (0.02% vs 0.15%, aOR 0.12, 95% CI 0.10-0.15) in individuals without this history. Among individuals with a history of brachial plexus birth injury, 48.1 cesarean deliveries are needed to prevent one brachial plexus birth injury. CONCLUSIONS: Parity, previous shoulder dystocia, and previously delivering a neonate with brachial plexus birth injury are associated with future brachial plexus birth injury risk. These factors are identifiable prenatally and can inform discussions with pregnant individuals regarding brachial plexus birth injury risk and planned mode of delivery.

Maternal Epidemiology of Brachial Plexus Birth Injuries in California: 1996 to 2012.

OBJECTIVE: This study aimed to evaluate the incidence of brachial plexus birth injury (BPBI) and its associations with maternal demographic factors. Additionally, we sought to determine whether longitudinal changes in BPBI incidence differed by maternal demographics. STUDY DESIGN: We conducted a retrospective cohort study of over 8 million maternal-infant pairs using California's Office of Statewide Health Planning and Development Linked Birth Files from 1991 to 2012. Descriptive statistics were used to determine BPBI incidence and the prevalence of maternal demographic factors (race, ethnicity, age). Multivariable logistic regression was used to determine associations of year, maternal race, ethnicity, and age with BPBI. Excess population-level risk associated with these characteristics was determined by calculating population attributable fractions. RESULTS: The incidence of BPBI between 1991 and 2012 was 1.28 per 1,000 live births, with peak incidence of 1.84 per 1,000 in 1998 and low of 0.9 per 1,000 in 2008. Incidence varied by demographic group, with infants of Black (1.78 per 1,000) and Hispanic (1.34 per 1,000) mothers having higher incidences compared with White (1.25 per 1,000), Asian (0.8 per 1,000), Native American (1.29 per 1,000), other race (1.35 per 1,000), and non-Hispanic (1.15 per 1,000) mothers. After controlling for delivery method, macrosomia, shoulder dystocia, and year, infants of Black (adjusted odds ratio [AOR] = 1.88, 95% confidence interval [CI] = 1.70, 2.08), Hispanic (AOR = 1.25, 95% CI = 1.18, 1.32), and advanced-age mothers (AOR = 1.16, 95% CI = 1.09, 1.25) were at increased risk. Disparities in risk experienced by Black, Hispanic, and advanced-age mothers contributed to a 5, 10, and 2% excess risk at the population level, respectively. Longitudinal trends in incidence did not vary among demographic groups. Population-level changes in maternal demographics did not explain changes in incidence over time. CONCLUSION: Although BPBI incidence has decreased in California, demographic disparities exist. Infants of Black, Hispanic, and advanced-age mothers are at increased BPBI risk compared with White, non-Hispanic, and younger mothers. KEY POINTS: · The incidence of BPBI has decreased over time.. · Demographic disparities in BPBI incidence and risk exist.. · Infants of Black, Hispanic, and advanced age mothers are at greatest risk of BPBI..

Positive predictive value of a single nucleotide polymorphism (SNP)-based NIPT for aneuploidy in twins: Experience from clinical practice.

OBJECTIVE: Twins account for approximately 1 in 30 live births in the United States. However, there are limited clinical experience studies published in noninvasive prenatal testing (NIPT) for detecting aneuploidies in twins. This study reports the performance of an SNP-based NIPT in the largest cohort with known outcomes for high-risk aneuploidy results. METHOD: This is a retrospective analysis of 18,984 results from commercial single-nucleotide polymorphism (SNP)-based NIPT tests performed in twins between October 2, 2017 and December 31, 2019. Follow-up for all 211 high-risk cases was solicited. RESULTS: Follow-up outcomes were obtained in 105 cases. Positive predictive values (PPVs) for high-risk results were 88.7% (63/71, 95% Confidence Interval [CI]: 79.0%-95.0%) for trisomy 21% and 72.7% (8/11, 95% CI: 39.0%-94.0%) for trisomy 18. The results were stratified into monozygotic (MZ) and dizygotic (DZ). The PPVs in MZ were 100% for both trisomy 21 (4/4, 95% CI: 40%-100%) and trisomy 18 (1/1, 95% CI: 2.5%-100%). No trisomy 13 cases were detected in the MZ group. The PPVs in DZ were 88.1% (59/67, 95% CI: 77.8%-94.7%), 70.0% (7/10, 95% CI: 34.8%-93.3%), and 66.7% (2/3, 95% CI: 9.4%-99.2%) for trisomy 21, trisomy 18, and trisomy 13, respectively. CONCLUSION: The performance of SNP-based NIPT in this large twin cohort was comparable to previously reported twin NIPT studies. SNP-based NIPT allows for zygosity-based PPV assessment.

Towards Noninvasive Accurate Detection of Intrapartum Fetal Hypoxic Distress.

Current intrapartum fetal well-being assessment is performed using electronic fetal monitoring (EFM), technically referred to as cardiotocography (CTG), which transabdominally monitors fetal heart rate (FHR) in relationship to maternal uterine contractions. Sometimes the deceleration in FHR following a uterine contraction can be sign of fetal hypoxic distress, but it may also be a normal physiological response. Multiple studies have shown that EFM has a high false positive rate for detecting fetal hypoxia. This has caused a rise in emergency Cesarean section (C-section) deliveries performed in the US over the years, while the rates of various conditions associated with anoxic brain injury at birth remain unchanged. The underlying problem is that many factors other than hypoxia can cause non-reassuring CTG traces and a more objective measure of oxygen supply to the fetal brain is not conveniently available. We are working to develop a transabdominal fetal pulse oximetry (TFO) system to non-invasively measure fetal arterial blood oxygen saturation (FSpO2) in order to enhance intrapartum fetal monitoring. This paper gives an overview of the past and ongoing work performed to develop TFO, highlights the main engineering and clinical challenges faced and presents preliminary results that demonstrate feasibility of TFO in both pregnant sheep models and human subjects.

Design and In Vivo Evaluation of a Non-Invasive Transabdominal Fetal Pulse Oximeter.

OBJECTIVE: Current intrapartum fetal monitoring technology is unable to provide physicians with an objective metric of fetal well-being, leading to degraded patient outcomes and increased litigation costs. Fetal oxygen saturation (SpO2) is a more suitable measure of fetal distress, but the inaccessibility of the fetus prior to birth makes this impossible to capture through current means. In this paper, we present a fully non-invasive, transabdominal fetal oximetry (TFO) system that provides in utero measures of fetal SpO2. METHODS: TFO is performed by placing a reflectance-mode optode on the maternal abdomen and sending photons into the body to investigate the underlying fetal tissue. The proposed TFO system design consists of a multi-detector optode, an embedded optode control system, and custom user-interface software. To evaluate the developed TFO system, we utilized an in utero hypoxic fetal lamb model and performed controlled desaturation experiments while capturing gold standard arterial blood gases (SaO2). RESULTS: Various degrees of fetal hypoxia were induced with true SaO2 values ranging between 10.5% and 66%. The non-invasive TFO system was able to accurately measure these fetal SpO2 values, supported by a root mean-squared error of 6.37% and strong measures of agreement with the gold standard. CONCLUSION: The results support the efficacy of the presented TFO system to non-invasively measure a wide-range of fetal SpO2 values and identify critical levels of fetal hypoxia. SIGNIFICANCE: TFO has the potential to improve fetal outcomes by providing obstetricians with a non-invasive measure of fetal oxygen saturation prior to delivery.

Validation of a Novel Transabdominal Fetal Oximeter in a Hypoxic Fetal Lamb Model.

Current intrapartum fetal oxygen saturation (SaO2) monitoring methodologies are limited, mostly consisting of fetal heart rate monitoring which is a poor predictor of fetal hypoxia. A newly developed transabdominal fetal oximeter (TFO) may be able to determine fetal SaO2 non-invasively. This study is to validate a novel TFO in determining fetal SaO2 in a hypoxic fetal lamb model. Fetal hypoxia was induced in at-term pregnant ewe by placing an aortic occlusion balloon infrarenally and inflating it in a stepwise fashion to decrease blood flow to the uterine artery. The inflation was held at each step for 10 min, and fetal arterial blood gases (ABGs) were intermittently recorded from the fetal carotid artery. The balloon catheter was deflated when fetal SaO2 fell below 15%, and the fetus was recovered. A total of three desaturation experiments were performed. The average fetal SpO2 reported by the TFO was derived at each hypoxic level and correlated with the ABG measures. Fetal SaO2 from the ABGs ranged from 10.5 to 66%. The TFO SpO2 correlated with the ABG fetal SaO2 (r-squared = 0.856) with no significant differences (p > 0.5). The fetal SpO2 measurements from TFO were significantly different than the maternal SpO2 (p < 0.01), which suggests that the transcutaneous measurements are penetrating through the maternal abdomen sufficiently and are expressing the underlying fetal tissue physiology. The recently developed TFO system was able to non-invasively report the fetal SpO2, which showed strong correlation with ABG measures and showed no significant differences.

Validation of a Single-Nucleotide Polymorphism-Based Non-Invasive Prenatal Test in Twin Gestations: Determination of Zygosity, Individual Fetal Sex, and Fetal Aneuploidy.

We analyzed maternal plasma cell-free DNA samples from twin pregnancies in a prospective blinded study to validate a single-nucleotide polymorphism (SNP)-based non-invasive prenatal test (NIPT) for zygosity, fetal sex, and aneuploidy. Zygosity was evaluated by looking for either one or two fetal genome complements, fetal sex was evaluated by evaluating Y-chromosome loci, and aneuploidy was assessed through SNP ratios. Zygosity was correctly predicted in 100% of cases (93/93; 95% confidence interval (CI) 96.1%-100%). Individual fetal sex for both twins was also called with 100% accuracy (102/102; 95% weighted CI 95.2%-100%). All cases with copy number truth were also correctly identified. The dizygotic aneuploidy sensitivity was 100% (10/10; 95% CI 69.2%-100%), and overall specificity was 100% (96/96; 95% weighted CI, 94.8%-100%). The mean fetal fraction (FF) of monozygotic twins (n = 43) was 13.0% (standard deviation (SD), 4.5%); for dizygotic twins (n = 79), the mean lower FF was 6.5% (SD, 3.1%) and the mean higher FF was 8.1% (SD, 3.5%). We conclude SNP-based NIPT for zygosity is of value when chorionicity is uncertain or anomalies are identified. Zygosity, fetal sex, and aneuploidy are complementary evaluations that can be carried out on the same specimen as early as 9 weeks' gestation.

A Standardized Approach for Category II Fetal Heart Rate with Significant Decelerations: Maternal and Neonatal Outcomes.

OBJECTIVE: To determine if a standardized intervention process for Category II fetal heart rates (FHRs) with significant decels (SigDecels) would improve neonatal outcome and to determine the impact on mode of delivery rates. STUDY DESIGN: Patients with Category II FHRs from six hospitals were prospectively managed using a standardized approach based on the presence of recurrent SigDecels. Maternal and neonatal outcomes were compared between pre- (6 months) and post-(11 months) implementation. Neonatal outcomes were: 5-minute APGAR scores of <7, <5, <3, and severe unexpected newborn complications (UNC). Maternal outcomes included primary cesarean and operative vaginal birth rates of eligible deliveries. RESULTS: Post implementation there were 8,515 eligible deliveries, 3,799 (44.6%) were screened, and 361 (9.5%) met criteria for recurrent SigDecels. Compliance with the algorithm was 97.8%. The algorithm recommended delivery in 68.0% of cases. Relative to pre-implementation, 5-minute APGAR score of <7 were reduced by 24.6% (p < 0.05) and severe UNC by -26.6%, p = < .05. The rate of primary cesarean decreased (19.8 vs 18.3%, p < 0.05), while there were nonsignificant increases in vaginal (74.6 vs 75.8%, p = 0.13) and operative vaginal births (5.7 vs 5.9%, p = 0.6). CONCLUSION: Standardized management of recurrent SigDecels reduced the rate of 5-minute APGAR scores of < 7 and severe UNC.

A Comparison of the Nulliparous-Term-Singleton-Vertex and Society of Maternal-Fetal Medicine Cesarean Birth Metrics Based on Hospital Size.

OBJECTIVE: The purpose of this study was to compare the nulliparous-term-singleton-vertex (NTSV) and the Society of Maternal-Fetal Medicine (SMFM) cesarean birth metrics as tools for quality improvement efforts based on hospital size. MATERIALS AND METHODS: Cesarean birth rates from 275 hospitals from six states were used to evaluate the NTSV metric and 81 hospitals from four states for the SMFM metric. Data were assessed based on delivery volume, their use as an effective tool for ongoing quality improvement programs, and their ability to serve as performance-based payline indicators. RESULTS: The average NTSV and SMFM cesarean birth rates were 25.6 and 13.0%, respectively. The number of deliveries included in the NTSV metric was stable across all hospital sizes (33.1-36.2%). With the SMFM metric, there was a progressive decline in the number of deliveries included, 90.0 versus 69.6%, in relatively small to large facilities. Variability was less and precision increased with the SMFM metric, which reduced the number of hospitals that could be incorrectly categorized when using performance-based predefined cesarean birth rate paylines. CONCLUSION: The SMFM metric appears to be better suited as a tool for rapid process improvement programs aimed at reducing cesarean birth rates in low-risk patients.

Early standardized treatment of critical blood pressure elevations is associated with a reduction in eclampsia and severe maternal morbidity.

BACKGROUND: Hypertensive disorders of pregnancy result in significant maternal morbidity and mortality. State and national guidelines have been proposed to increase treatment of patients with hypertensive emergencies or critically elevated blood pressures. There are limited data available to assess the impact of these recommendations on maternal morbidity. OBJECTIVE: The purpose of this prospective quality improvement project was to determine if maternal morbidity would be improved using a standardized approach for treatment of critically elevated blood pressures. STUDY DESIGN: In all, 23 hospitals participated in this project. Treatment recommendations included the use of an intravenous blood pressure medication and magnesium sulfate when there was a sustained blood pressure of ≥160 mm Hg systolic and/or ≥110 mm Hg diastolic. Compliance with the metric recommendations was monitored based on the number of patients treated with an intravenous blood pressure medication, use of magnesium sulfate, and if they received a timely postpartum follow-up appointment. The metric was scored as all or none; missing any of the 3 metric components was considered noncompliant. From January through June 2015 baseline data were collected and hospitals were made aware that ongoing monitoring of compliance would begin in July 2015 through June 2016. The primary outcomes were composite metric compliance, the incidence of eclampsia per 1000 births, and severe maternal morbidity. RESULTS: During the 18 months of this study there were 69,449 births. Within this population, 2034 met criteria for a critically elevated blood pressure, preeclampsia, or superimposed preeclampsia with severe features. Of this group, 1520 had a sustained critical blood elevation. Initial compliance with treatment recommendations was low (50.5%) and increased to >90% after April 2016 (P < .001). Compliance with utilization of intravenous blood pressure medication increased by 33.2%, from a baseline of 57.1-90.3% (P < .01) during the last 6 months of monitoring. Compliance with utilization of magnesium sulfate increased by 10.8%, from a baseline of 85.4-96.2% (P < .01). The incidence of eclampsia declined by 42.6% (1.15 ± 0.15/1000 to 0.62 ± 0.09/1000 births). Severe maternal morbidity decreased by 16.7% from 2.4 ± 0.10% to 2.0 ± 0.15% (P < .01). CONCLUSION: We noted 3 important findings: (1) compliance with state and national treatment guidelines is low without monitoring; (2) high levels of compliance can be achieved in a relatively short period of time; and (3) early intervention with intravenous blood pressure medication and magnesium sulfate for verified sustained critical maternal blood pressures resulted in a significant reduction in the rate of eclampsia and severe maternal morbidity. The reduction in the rate of eclampsia could only partially be attributed to the increase in the use of magnesium sulfate, suggesting an additive or synergistic effect of the combined treatment of an antihypertensive medication and magnesium sulfate on the rate of eclampsia and severe maternal morbidity.

Decreased rates of shoulder dystocia and brachial plexus injury via an evidence-based practice bundle.

OBJECTIVE: To evaluate whether a standardized approach to identify pregnant women at risk for shoulder dystocia (SD) is associated with reduced incidence of SD and brachial plexus injury (BPI). METHODS: Between 2011 and 2015, prospective data were collected from 29 community-based hospitals in the USA during implementation of an evidence-based practice bundle, including an admission risk assessment, required "timeout" before operative vaginal delivery (OVD), and low-fidelity SD drills. All women with singleton vertex pregnancies admitted for vaginal delivery were included. Rates of SD, BPI, OVD, and cesarean delivery were compared between a baseline period (January 2011-September 2013) and an intervention period (October 2013-June 2015), during which there was a system-wide average bundle compliance of 90%. RESULTS: There was a significant reduction in the incidence of SD (17.6%; P=0.028), BPI (28.6%; P=0.018), and OVD (18.0%; P<0.001) after implementation of the evidence-based practice bundle. There was a nonsignificant reduction in primary (P=0.823) and total (P=0.396) cesarean rates, but no association between SD drills and incidence of BPI. CONCLUSION: Implementation of a standard evidence-based practice bundle was found to be associated with a significant reduction in the incidence of SD and BPI. Utilization of low-fidelity drills was not associated with a reduction in BPI.

Use of Maternal Early Warning Trigger tool reduces maternal morbidity.

BACKGROUND: Maternal mortality in the United States has increased unabated for the past 20 years. Maternal morbidity is also affecting an increasingly large number of women in the United States. A number of national and state organizations have recommend the use of maternal early warning tools as a method to combat this problem. There are limited data suggesting that the use of these types of clinical assessment tools can reduce maternal morbidity. OBJECTIVE: We sought to determine if maternal morbidity could be reduced with the implementation of a clinical pathway-specific Maternal Early Warning Trigger (MEWT) tool. STUDY DESIGN: The tool was developed internally and prospectively implemented as a pilot project in 6 of 29 hospitals within a large hospital system. The primary goal was early assessment and treatment of patients suspected of clinical deterioration. The tool addressed the 4 most common areas of maternal morbidity: sepsis, cardiopulmonary dysfunction, preeclampsia-hypertension, and hemorrhage. To be considered positive, triggers needed to be sustained for >20 minutes and were defined as severe (single abnormal value): maternal heart rate (HR) >130 beats/min (bpm), respiratory rate >30/min, mean arterial pressure <55 mm Hg, oxygen saturation <90%, or nurse concern; or nonsevere (required 2 abnormal values): temperature >38 or <36°C, blood pressure >160/110 or <85/45 mm Hg, HR >110 or <50 bpm, respiratory rate >24 or <10/min, oxygen saturation <93%, fetal HR >160 bpm, altered mental status, or disproportionate pain. Within each group, recommended management or assessment was also provided. Outcome measures were Centers for Disease Control and Prevention (CDC)-defined severe maternal morbidity, composite maternal morbidity, and intensive care unit (ICU) admissions. Two time intervals were used to analyze the effect of the MEWT tool: a 24-month baseline control period and a 13-month MEWT study period. To determine that the findings noted were not simply changes that would have occurred without the utilization of the early warning tool, we also compared a control population from nonpilot sites during the same baseline and 13-month time periods. RESULTS: There were 36,832 deliveries at the pilot sites (24,221 pre- and 12,611 post-MEWT testing) and 146,359 at the nonpilot sites (95,718 pre- and 50,641 post-MEWT testing) during the 2 study time periods. Use of the MEWT tool resulted in significant reductions in CDC severe maternal morbidity (P < 0.01) and composite morbidity (P < 0.01). ICU admissions were unchanged. At nonpilot sites CDC severe maternal morbidity, composite morbidity, and ICU admissions were unchanged between baseline and the post-MEWT testing time period. CONCLUSION: The use of the MEWT tool in this study, designed to address 4 of the most common causes of maternal morbidity, as well as provide assessment and management recommendations, resulted in significant improvement in maternal morbidity. The variation in hospital delivery services at the pilot sites suggests that this maternal early warning tool would be suitable for use in the majority of maternity centers in the United States.

Baseline assessment of a hospital-specific early warning trigger system for reducing maternal morbidity.

OBJECTIVE: To determine whether predefined maternal early warning triggers (MEWTs) can predict pregnancy morbidity. METHODS: In a retrospective case-control study, obstetric patients admitted to the intensive care unit (ICU) between 2012 and 2013 at seven pilot US hospitals were compared with control patients who had a normal delivery outcome. Six MEWTs were assessed. RESULTS: The case and control groups each contained 50 patients. Hemorrhage (15/50, 30%), sepsis (12/50, 24%), cardiac dysfunction (8/50, 16%), and pre-eclampsia (6/50, 12%) were the most common reasons for ICU admission. Significant associations were recorded between ICU admission and tachycardia (OR 5.0, 95% CI 2.1-11.7), mean arterial pressure less than 65 mm Hg (OR 4.5, 95% CI 1.9-10.8), temperature of at least 38°C (OR 44.1, 95% CI 13.0-839.1), and altered mental state (OR 44.1, 95% CI 13.1-839.0). Two or more triggers were persistent for 30 minutes or more in 36 (72%) ICU patients versus 2 (4%) controls (OR 61.7, 95% CI 13.2-288.0). Earlier medical intervention might have led to a lesser degree of maternal morbidity for 31 (62%) ICU patients with at least one MEWT. CONCLUSION: Persistent MEWTs were present in most obstetric ICU cases. Retrospectively, MEWTs in this cohort seemed to separate normal obstetric patients from those for whom ICU admission was indicated; their use might reduce maternal morbidity.

Is there value for serial ultrasonographic assessment of cervical lengths after a cerclage?

OBJECTIVE: The objective of the study was to determine the value of serial ultrasonographic cervical length (CL) measurements after cerclage to predict preterm delivery. STUDY DESIGN: Retrospective ultrasonographic and outcome data from singleton pregnancies with cerclage were reviewed. Using transvaginal ultrasound (TVS), overall CL obtained before cerclage placement, 2 weeks after cerclage, and before delivery were compared between women who delivered preterm (less than 37 weeks) and term. The overall CL including CL above (CLA) and below the cerclage (CLB) were compared using the SAS program. RESULTS: Cerclage was placed at 15.7 +/- 3.6 weeks (mean +/- SD) in 57 women. The overall CL before cerclage, 2 weeks after cerclage, and the last TVS before delivery was not different in preterm and term births. The odds ratio of a measurable CLA for preterm delivery by TVS was 0.87 (0.78 to 0.95, 95% confidence interval). Thirty-two patients (56%) had absent CLA at 26.7 +/- 4.4 weeks. Of these, 16 (50%) were delivered for preterm premature rupture of membranes (PPROM) and chorioamnionitis (sensitivity of 100%, specificity of 61%, positive predictive value of 50%, and negative predictive value of 100%). CONCLUSION: Although the overall cervical length by serial TVS after cerclage did not predict preterm birth, absent CLA is associated with preterm delivery, chorioamnionitis, and PPROM.

A retrospective review of isoimmunized pregnancies managed by middle cerebral artery peak systolic velocity.

OBJECTIVE: The purpose of this study was to determine the clinical outcome of isoimmunized pregnancies managed primarily by middle cerebral artery peak systolic velocity. STUDY DESIGN: A retrospective chart review was conducted of isoimmunized pregnancies that underwent ultrasound examinations from January 1, 2001, through May 1, 2003. Ultrasound reports, laboratory tests, and maternal and neonatal charts were reviewed. RESULTS: Women with a clinically significant red blood cell antibody and titer value were included. The study population consisted of 39 women (40 pregnancies, 42 fetuses). Patients with a middle cerebral artery peak systolic velocity of > or =1.5 MoM were offered amniocentesis. Seven pregnancies had an abnormal middle cerebral artery peak systolic velocity. Three of these infants had significant anemia. Six of the 7 pregnancies required an exchange transfusion. None of the 33 pregnancies (35 neonates) with normal middle cerebral artery peak systolic velocity measurements resulted in a neonate with significant anemia or severe hyperbilirubinemia. CONCLUSION: The clinical outcome of these pregnancies supports the use of middle cerebral artery peak systolic velocity measurements in the management of isoimmunized pregnancies.