Faculty Bibliography

BACKGROUND:The relationship between fetal fraction and birth weight in twin gestations is poorly understood. OBJECTIVE:To investigate the relationship between first trimester cfDNA fetal fraction and birth weight < 10th percentile in twin gestations. STUDY DESIGN/METHODS:This is a planned secondary analysis of the Twin cfDNA Study, a 17-center retrospective cohort of twin pregnancies screened for aneuploidy using cfDNA in the first trimester from 12/2011 - 2/2022, excluding those with positive screen results for chromosomal aneuploidy. CfDNA testing was performed by a single lab using massively parallel sequencing (MPSS). Baseline characteristics and birth weight of pregnancies with normal fetal fraction were compared to those with low (<5%) and high (>95%) fetal fraction using univariable analyses and multivariable regression. RESULTS:A total of 1041 twin pregnancies were included. Chronic hypertension, elevated BMI, and self-identified Black race were associated with fetal fraction <5th percentile. There was no difference in median fetal fraction between those with birth weight <10th percentile in at least one twin (median [IQR] fetal fraction 12.2% [9.8, 14.8] versus those with normal birth weight (10th percentile) in both twins (median [IQR] fetal fraction 12.3% [9.7, 15.2] for normal birth weight, p = 0.49). There was no association between high or low fetal fraction and birth weight <10th percentile for one (p=0.45) or both (p=0.81) twins, and there was no association between high or low fetal fraction and birth weight <5th percentile for one (p=0.44) or both (p=0.74) twins. The results were unchanged after adjustment for potential confounders. CONCLUSION/CONCLUSIONS:In this large cohort, there was no association between the extremes of cfDNA fetal fraction and birthweight < 10th percentile, suggesting that first trimester fetal fraction may not predict impaired fetal growth in twin gestations.

OBJECTIVE:Social determinants of health (SDOH) may impact the incidence of Respiratory Syncytial Virus (RSV) infection and the uptake of vaccinations in pregnancy. The objective of this study is to identify contributors to disparities in RSV vaccination in pregnancy. DESIGN/METHODS:This is a retrospective cohort study of patients delivering at term within three hospitals during February and March 2024, comparing pregnant patients identified as receiving vs not receiving RSV vaccinations. This period and gestational age were chosen to include patients who would have qualified for RSV vaccination administration. Vaccination status was extracted from standardized admission templates where these variables were recorded as discrete fields. Patients without RSV vaccination information were excluded. Sociodemographic factors, COVID vaccination status, and delivery campus were evaluated. Outcomes were analyzed using chi-squared, t-test, and McNemar test. RESULT/RESULTS:2181 patients met inclusion criteria and RSV vaccination information was available for 1548 patients (71%) with a 14% vaccination rate. Compared to those not vaccinated (n=1332), RSV vaccinated patients (n=216) were more likely to be older (30.7 vs 34.8, p<0.001), have private insurance (42% vs 85%, p<0.001), speak English (82% vs 95%, p<0.001), and deliver at our regional perinatal center (26% vs 77%, p<0.001). 50% of RSV vaccinated patients had a history of COVID vaccination compared to 33% of those not vaccinated against RSV (p<0.001). CONCLUSIONS:SDOH were associated with differences in RSV vaccination status. In addition, patients without RSV vaccination were less likely to have had COVID vaccination. These findings highlight the need to address SDOH to increase vaccination rates for vulnerable populations.

OBJECTIVE:To investigate the relationship between platelet indices (count, size and production/immaturity) and hypertensive disorders of pregnancy. STUDY DESIGN/METHODS:This was a secondary analysis of a prospective cohort of pregnant individuals followed from first trimester through delivery at an academic tertiary care institution. Routine platelet indices obtained prospectively during prenatal care and delivery were compared between those who developed a hypertensive disorder of pregnancy and those who did not. We assessed platelet count (by trimester), mean platelet volume, and immature platelet fraction measured as percent (%) and absolute count. Data were analyzed using Fisher's Exact test, chi-square test, and multivariable logistic regression. P < 0.05 was considered statistically significant. RESULTS: = 0.01) compared to those without a hypertensive disorder of pregnancy, after adjusting for age, race/ethnicity, obesity, nulliparity, and chronic hypertension. The prevalence and likelihood of a hypertensive disorder of pregnancy increased with increasing mean platelet volume, as well as with both the percent and absolute immature platelet fraction. There was no difference between groups in platelet count in the first trimester, second trimester, or at delivery. CONCLUSIONS:An increase in platelet size and immaturity was observed in those with a hypertensive disorder of pregnancy. These data support further investigation of platelets in the mechanisms of the development of hypertensive disorders of pregnancy and the use of platelet indices to better identify high risk groups in pregnancy.

Vasa previa is an abnormality of the umbilical cord and fetal membranes that affects ∼1 in 1300 pregnancies. The diagnosis is made by visualization of velamentous fetal vessels coursing within the membranes over the cervix unprotected by Wharton jelly or placenta. When it is not diagnosed prenatally, it is associated with a high risk of fetal death. Prenatal diagnosis of vasa previa using ultrasound, followed by close surveillance, and appropriately timed late preterm delivery by cesarean is associated with intact survival in >95% of cases. In this review, we review epidemiology, risk factors, diagnosis, and management of patients with vasa previa.

BACKGROUND:There are limited data to guide the diagnosis and management of vasa previa. Currently, what is known is largely based on case reports or series and cohort studies. OBJECTIVE:(s): To systematically collect and classify expert opinions and achieve consensus on the diagnosis and clinical management of vasa previa using focus group discussions (FGD) and a Delphi technique. STUDY DESIGN/METHODS:A four-round FGD and a three-round Delphi survey of an international panel of experts on vasa previa were conducted. Experts were selected based on their publication record on vasa previa. First, we convened an FGD panel of 20 experts and agreed on which issues were unresolved in the diagnosis and management of vasa previa. A three-round anonymous electronic survey was then sent to the full expert panel. Survey questions were presented on the diagnosis and management of vasa previa that the experts were asked to rate on a 5-point Likert scale (from strongly disagree = 1 to strongly agree = 5). Consensus was defined as a median score of 5. Following responses to each round, any statements that had median scores of 3 or less were deemed to have had no consensus and excluded. Statements with a median score of 4 were revised and re-presented to the experts in the next round. Consensus and non-consensus statements were then aggregated. RESULTS:Sixty-eight international experts were invited to participate in the study, of which 57 participated. Experts were from 13 countries on five continents and have contributed to over 80% of published cohort studies on vasa previa, as well as national and international society guidelines. Completion rates were 84%, 93%, 91% for the first, second, and third rounds, respectively, and 71% completed all three rounds. The panel reached a consensus on 26 statements regarding the diagnosis and key points of management of vasa previa, including: 1) While there is no agreement on a distance between the fetal vessels and the cervical internal os to define vasa previa, the definition should not be limited to a 2 cm distance; 2) All pregnancies should be screened for vasa previa with routine examination for placental cord insertion and a color Doppler sweep of the region over the cervix at the second-trimester anatomy scan; 3) When a low-lying placenta or placenta previa is found in the second trimester, a transvaginal ultrasound with Doppler should be performed at around 32 weeks to rule out vasa previa; 4) Outpatient management of asymptomatic patients without risk factors for preterm birth is reasonable; 5)Asymptomatic patients with vasa previa should be delivered by scheduled cesarean between 35- and 37-weeks of gestation; and 6) There was no agreement on routine hospitalization, avoidance of intercourse, or use of 3-dimensional ultrasound for diagnosis of vasa previa. CONCLUSIONS:Through FGD and a Delphi process, an international expert panel reached consensus on the definition, screening, clinical management, and timing of delivery in vasa previa, which could inform the development of new clinical guidelines.

BACKGROUND:Accurate individualized assessment of preeclampsia risk enables the identification of patients most likely to benefit from initiation of low-dose aspirin at 12 to 16 weeks of gestation when there is evidence for its effectiveness, and enables the guidance of appropriate pregnancy care pathways and surveillance. OBJECTIVE:The primary objective of this study was to evaluate the performance of artificial neural network models for the prediction of preterm preeclampsia (<37 weeks' gestation) using patient characteristics available at the first antenatal visit and data from prenatal cell-free DNA screening. Secondary outcomes were prediction of early-onset preeclampsia (<34 weeks' gestation) and term preeclampsia (≥37 weeks' gestation). METHODS:This secondary analysis of a prospective, multicenter, observational prenatal cell-free DNA screening study (SMART) included singleton pregnancies with known pregnancy outcomes. Thirteen patient characteristics that are routinely collected at the first prenatal visit and 2 characteristics of cell-free DNA (total cell-free DNA and fetal fraction) were used to develop predictive models for early-onset (<34 weeks), preterm (<37 weeks), and term (≥37 weeks) preeclampsia. For the models, the "reference" classifier was a shallow logistic regression model. We also explored several feedforward (nonlinear) neural network architectures with ≥1 hidden layers, and compared their performance with the logistic regression model. We selected a simple neural network model built with 1 hidden layer and made up of 15 units. RESULTS:Of the 17,520 participants included in the final analysis, 72 (0.4%) developed early-onset, 251 (1.4%) preterm, and 420 (2.4%) term preeclampsia. Median gestational age at cell-free DNA measurement was 12.6 weeks, and 2155 (12.3%) had their cell-free DNA measurement at ≥16 weeks' gestation. Preeclampsia was associated with higher total cell-free DNA (median, 362.3 vs 339.0 copies/mL cell-free DNA; P<.001) and lower fetal fraction (median, 7.5% vs 9.4%; P<.001). The expected, cross-validated area under the curve scores for early-onset, preterm, and term preeclampsia were 0.782, 0.801, and 0.712, respectively, for the logistic regression model, and 0.797, 0.800, and 0.713, respectively, for the neural network model. At a screen-positive rate of 15%, sensitivity for preterm preeclampsia was 58.4% (95% confidence interval, 0.569-0.599) for the logistic regression model and 59.3% (95% confidence interval, 0.578-0.608) for the neural network model. The contribution of both total cell-free DNA and fetal fraction to the prediction of term and preterm preeclampsia was negligible. For early-onset preeclampsia, removal of the total cell-free DNA and fetal fraction features from the neural network model was associated with a 6.9% decrease in sensitivity at a 15% screen-positive rate, from 54.9% (95% confidence interval, 52.9-56.9) to 48.0% (95% confidence interval, 45.0-51.0). CONCLUSION/CONCLUSIONS:Routinely available patient characteristics and cell-free DNA markers can be used to predict preeclampsia with performance comparable to that of other patient characteristic models for the prediction of preterm preeclampsia. Logistic regression and neural network models showed similar performance.

We present a case of a vein of Galen aneurysmal malformation (VGAM), a rare congenital arteriovenous malformation, in one fetus of a monochorionic-diamniotic twin pregnancy. The diagnosis was made with color Doppler ultrasonography at 28 weeks and the affected fetus was found to have worsening cardiomegaly on subsequent fetal echocardiograms. She was emergently delivered at 32 weeks for abnormal fetal heart rate tracing of the affected twin. Magnetic resonance imaging of the brain findings after delivery demonstrated severe neurological injury; therefore, postnatal embolization was not performed. The neonate died on day of life 9. The cotwin survived without neurological complications. This is the first case in the literature of a VGAM diagnosed prenatally in a monochorionic-diamniotic twin pregnancy and demonstrates the challenge of delivery timing with prenatal diagnosis in a twin pregnancy.

PURPOSE/OBJECTIVE:The objective of this study was to compare maternal and neonatal outcomes when the diagnosis of FGR was based on isolated abdominal circumference < 10th percentile for gestational age (GA) (iAC group) versus overall estimated fetal weight < 10th percentile (EFW group). METHODS:, and Fisher exact tests with significance defined as p < 0.05. RESULTS:635 women met the inclusion criteria, 259 women in the iAC group and 376 women in the EFW group. The iAC group was noted to have a later GA at diagnosis and delivery. iAC was associated with lower rates of preterm birth (PTB), NICU admission, SGA at delivery and umbilical artery cord gas < 7.0. CONCLUSION/CONCLUSIONS:Using iAC as a definition of FGR increased the number of FGR cases by 1.69-fold over EFW criteria alone. However, obstetrical and neonatal outcomes for the iAC group appear to be significantly better than those in the EFW group, with low rates of PTB, NICU admission, and umbilical artery cord gas < 7.0.

BACKGROUND:Biologically active cervical glands provide a mucous barrier while influencing the composition and biomechanical strength of the cervical extracellular matrix. Cervical remodeling during ripening may be reflected as loss of the sonographic cervical gland area. As sonographic cervical length remains suboptimal for universal screening, adjunctive evaluation of other facets of the mid-trimester cervix may impart additional screening benefit. OBJECTIVE:To sonographically assess the cervical gland area at universal cervical length screening for preterm birth. STUDY DESIGN/METHODS:We performed a retrospective cohort study of singletons with transvaginal cervical length screening universally performed during anatomic survey between 18 0/7 and 23 6/7 weeks and subsequent live delivery at a single institution in 2018. Uterine anomalies, cerclage, suboptimal imaging, or medically indicated preterm birth were excluded. Ultrasound images were assessed for cervical length and cervical gland area (with quantitative measurements when present). The primary outcome was spontaneous preterm birth <37 weeks. Absent and present gland groups were compared using χ2, Fisher's exact, T-test, and multivariate logistic regression (adjusting for parity and progesterone use, as well as the gestational age, cervical length, and gland absence at screening ultrasound). Gland measurements were evaluated using the Mann-Whitney-U Test and Spearman's correlation. RESULTS:Among the cohort of 772 patients, absent and present CGA groups were overall similar. Patients were on average 33 years old, ∼20 weeks gestation at screening ultrasound, and overall, 2.5% had history of prior spontaneous preterm birth. The absent gland group was more likely to have been taking progesterone (17% vs 4%, p=0.04). Overall rate of preterm birth was 2.6%. However, the 2.3% of patients with absent cervical gland area were significantly more likely to deliver <37 weeks (aOR 23.9, 95% CI 6.4-89, p<0.001). Multivariate logistic regression demonstrated better performance of a cervical length screening model for preterm birth prediction with the addition of qualitative gland evaluation (p<0.001). Qualitative gland assessment was reproducible (PABAK 0.89), but quantitative gland measurements did not correlate with preterm birth. CONCLUSION/CONCLUSIONS:Qualitative gland absence at mid-gestation cervical length screening was associated with subsequent spontaneous preterm birth, whereas quantitative gland measurements were not. Multifaceted ultrasound screening may be needed to adequately evaluate the multiple biologic functions of the cervix.