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Background: Pregnancies complicated by fetal growth restriction are at increased risk of fetal demise and adverse neonatal outcomes. Distinguishing growth-restricted fetuses from constitutionally small ones remains challenging. Given the variability in current diagnostic criteria and the importance of identifying at-risk fetuses, fetal growth velocity has emerged as a predictor of adverse neonatal outcomes. Objective: To evaluate whether percentile-based fetal growth velocity, defined as change in estimated fetal weight percentile per week, predicts adverse neonatal outcomes in pregnancies affected by fetal growth restriction or small-for-gestational-age neonates. The primary aim was to determine the relationship between growth velocity and a composite of adverse neonatal outcomes. Study Design: This was a retrospective cohort study of pregnant patients 18 - 45 years old who delivered between August 2017 to December 2022 in a single healthcare system. Patients were excluded who had fewer than 2 ultrasounds after 16 weeks gestation, genetic or anatomic abnormalities, or a multiple gestation. Results: 300 patients met all inclusion criteria, and most patients (n=199) delivered at the tertiary care center. Three had an intrauterine fetal demise at a mean gestational age of 35w3d. 74 neonates were admitted to the NICU with a mean length of stay of 8.5 days; 29 required respiratory support. No neonatal deaths occurred. In fetuses with initial estimated fetal weight <3rd percentile (n=33), the probability of composite outcome was increased (50%, 95% CI 44.8-55.2) compared to those >50th percentile (5%, 95% CI 3.7-6.6). In the 3-10th and 10 - 50th percentile subgroups with decelerated growth, composite outcome rates were also increased (56.2% and 44.1%) compared to those with neutral or increased growth velocity. Conclusion: Percentile-based fetal growth velocity is a simple calculation that correlates with adverse neonatal outcomes regardless of initial estimated fetal weight. As fetal growth velocity decreased, our cohort saw increased rates of adverse outcomes. Change in EFW percentile normalizes for gestational age and allows ease of clinical interpretation. Decelerated growth identified fetuses at highest risk, suggesting growth velocity as a useful metric in routine surveillance.

ABSTRACT Objective(s) Fetal pleural effusion is a rare condition that may significantly impact fetal and neonatal outcomes. Currently, no universal standardized approach exists for diagnosing and managing primary fetal pleural effusions. This study aimed to develop structured, expert‐based clinical guidelines for the diagnosis, monitoring, management, and follow‐up care of primary fetal pleural effusion. Methods A Delphi method was employed to achieve consensus among an international panel of experts in fetal medicine. Experts were selected based on their clinical expertise, affiliations, and relevant publications. A three‐round anonymous electronic survey was sent to the full panel. In the initial two rounds, participants rated each statement on a Likert scale (1–5) and provided suggestions for modifications. Statements with a median score of five and no suggested changes were accepted as consensus. Statements with a median score below four were rejected. Statements scoring a median of four were revised according to suggestions and reconsidered in the subsequent round. In the final round, participants indicated their agreement or disagreement with the remaining statements. Consensus was defined as agreement from more than 70% of participants with no suggestions for further changes. Results A total of 101 expert clinicians accepted the invitation and completed the first round with 73 (72%) completing all three rounds. Consensus statements were achieved on aspects of diagnosis, monitoring, intervention, post‐intervention management, and delivery. Key recommendations concerning the diagnosis of primary fetal pleural effusion include the use of ultrasound as the primary modality for identifying fetal pleural effusion and excluding secondary causes through detailed genetic, infectious, and metabolic evaluations. Management strategies emphasized thoracoamniotic shunting as the preferred intervention in hydropic fetuses with primary pleural effusion. Experts reached consensus that shunt placement could be offered as early as 16 weeks. No consensus was reached for isolated effusion without hydrops, as management was considered case‐dependent. The importance of ultrasonographic monitoring of fetal status at least weekly post‐intervention was strongly endorsed. Conclusion(s) The Delphi method facilitated the development of a consensus‐based protocol for diagnosing and managing primary fetal pleural effusion. These standardized guidelines are intended to enhance clinical practice across various settings, improve perinatal outcomes, and serve as a foundation for future research for this high‐risk fetal condition.

Importance Anhydramnios from fetal kidney failure causes lethal pulmonary hypoplasia. Serial amnioinfusions have shown promise in mitigating pulmonary disease from bilateral renal agenesis, but efficacy and safety for other causes of fetal kidney failure are unproven. Objective To assess the efficacy of serial amnioinfusions initiated before 26 weeks’ gestation to mitigate lethal pulmonary hypoplasia in cases of anhydramnios due to fetal kidney failure. Design, Setting, and Participants Prospective, nonrandomized clinical trial conducted at 13 US fetal therapy centers from December 2018 to February 2025. Outcomes for maternal-fetal pairs with anhydramnios before 22 weeks’ gestation due to fetal kidney failure without bilateral renal agenesis are reported; data collection for surviving infants continued until February 13, 2026. Exposure Thirty-two participants underwent serial amnioinfusions with isotonic fluid beginning before 26 weeks’ gestation. Main Outcomes and Measures The primary end point was neonatal survival for 14 days or longer with dialysis access placement. Secondary outcome measures of survival to discharge home and kidney transplant are reported. Results Twenty-nine of 32 participants (91%) had a live birth, with a median (IQR) gestational age at delivery of 34 weeks 1 day (31 weeks 5 days to 34 weeks 6 days). All participants delivered before 37 weeks’ gestation. No unexpected serious maternal adverse events occurred, and the most common maternal complications were preterm prelabor rupture of membranes in 19 participants (56%) and chorioamniotic separation in 10 (29%). The primary outcome occurred in 19 (65.5%) of 29 live-born neonates (95% CI, 45.7%-82.1%). Factors associated with survival to the primary outcome included receiving more amnioinfusions (median [IQR], 14 [9-18] in survivors vs 7 [4-11] in nonsurvivors; P = .01), longer time interval from first amnioinfusion to preterm prelabor rupture of membranes (63.5 [60.5-74.5] days in survivors vs 29.0 [22.0-56.0] days in nonsurvivors; P = .01), gestational age greater than 32 weeks (79% of survivors vs 38% of nonsurvivors; P = .03), and higher birth weight (2029 [1770-2250] g in survivors vs 1635 [1185-1915] g in nonsurvivors; P = .01). Fourteen live-born infants (48%) survived to hospital discharge at a median (IQR) age of 4.7 (3.4-5.7) months. Of the 11 infants surviving to date, 7 (64%) have undergone kidney transplant between ages 2 years to 5 years. Conclusions and Relevance Serial amnioinfusions mitigated lethal pulmonary hypoplasia in neonates with anhydramnios due to fetal kidney failure. Significant neonatal morbidity and mortality independent of early lung function was noted. Factors associated with survival were consistent with the Renal Anhydramnios Fetal Therapy trial’s bilateral renal agenesis cohort, suggesting common mechanistic pathways for mitigating pulmonary hypoplasia. Trial Registration ClinicalTrials.gov Identifier: NCT03101891

Fetal repair of myelomeningocele remains an effective intervention to decrease hindbrain herniation and reduce the need for postnatal CSF shunting. Effectiveness depends on a watertight closure; however, there are challenges to achieving such. Often, a separate, watertight dural closure is difficult due to the thinness and fragility of the dural membrane. This video demonstrates the approach utilizing a previously described myofascial rotation of the bilateral paraspinal muscles to construct a robust closure even without the need for a separate dural closure or patch reinforcement. This method has been associated with improved primary closure rates and fewer postnatal procedures. The video can be found here: https://stream.cadmore.media/r10.3171/2026.1.FOCVID25235

BACKGROUND AND OBJECTIVES: Myelomeningocele is defined by the presence of a fluid-filled sac that contains the neural placode and cerebrospinal fluid (CSF) at the level of the spinal defect. Alternatively, the term myeloschisis is used when the neural placode is not contained within a CSF-filled sac. While both are eligible for prenatal closure, few studies have characterized the impact of the type of lesion on postnatal outcomes. This study compares the outcomes of these 2 types of open spinal dysraphism using data from the Fetal Myelomeningocele Consortium registry sponsored by the North American Fetal Therapy Network. METHODS: The prospective observational Fetal Myelomeningocele Consortium registry was used to extract deidentified data corresponding to patients who underwent fetal closure of myelomeningocele vs myeloschisis. Demographics, operative characteristics, perioperative complications, and postnatal outcomes were collected. RESULTS: A total of 1327 patients were identified, including 991 (74.7%) with myelomeningocele and 336 (25.3%) with myeloschisis. Compared with myelomeningocele, myeloschisis was associated with lower rates of prenatal talipes (11% vs 24%, P < .001) and higher rates of favorable prenatal movement (94% vs 86%, P < .001). Postnatally, myeloschisis conferred higher rates of leg movement (97% vs 90%, P = .002) and an increased likelihood of ambulation in the household (10.4% vs 4.1%, P = .009) and outside (7.2% vs 1.9%, P = .004) at 1 year. However, myeloschisis was also linked to greater use of skin patches during closure (49% vs 27%, P < .001), higher CSF leak rates among those with wound dehiscence (26% vs 8%, P = .014), and more frequent CSF diversion and tethered cord surgeries at follow-up. CONCLUSION: Myeloschisis and myelomeningocele demonstrate distinct clinical profiles. Although patients with myeloschisis may have favorable motor outcomes, they are also characterized by higher rates of CSF leakage, CSF diversion, and tethered cord surgery. These findings highlight the need for lesion-specific prognostication and may inform surgical planning and parental counseling in the context of prenatal spina bifida closure.

ABSTRACT Objective Fetal surgery (FS) for spina bifida (SB) repair improves infant outcomes; however, spontaneous preterm birth (sPTB) is common. We aimed to evaluate maternal and fetal immune responses following FS for SB repair. Method Pregnant participants undergoing fetoscopic SB repair at 24–26 weeks of gestational age (GA) were prospectively recruited and compared to GA matched low‐risk controls. Blood samples were collected at baseline, 2‐week post‐surgery (POD14), and delivery. Cytokine analysis, flow cytometry, and T cell receptor (TCR) sequencing were performed. Results sPTB occurred in 5/6 of the FS group (0/6 of controls). Maternal blood in the FS group demonstrated increased alpha‐fetoprotein (AFP) and anti‐inflammatory IL‐1RA at baseline and POD14, increased pro‐inflammatory IL‐8 only post‐operatively, and elevated growth factors throughout. T cell phenotypes following FS revealed reduced TH17 frequency but increased activation receptors on cytotoxic T cells. At delivery, the FS cohort had reduced Th2 and Th17 helper T cells and CD4+ memory T cells, but CD8 T cells still showed increased activation. No TCR expansion was detected post‐surgery, suggesting antigen‐independent activation. Cord blood in FS repaired neonates had increased AFP, IL‐8, IL‐1RA. Conclusion Systemic immune changes following FS, particularly T cell maturation and activation, were observed. Further characterization of these mechanisms may help predict and prevent surgery‐induced PTB, improving outcomes.

BACKGROUND AND OBJECTIVES: The Management of Myelomeningocele Study established a role for maternal-fetal surgery for myelomeningocele (MMC) but was limited to patients with a maternal body mass index (BMI) less than 35 kg/m 2 . However, as the rate of obesity has increased globally, some centers have extended the Management of Myelomeningocele Study criteria to include patients with a BMI of 35 to 40 kg/m 2 . We used the Fetal MMC Consortium registry to analyze the complications associated with maternal-fetal surgery in patients with a maternal BMI < 35 kg/m 2 compared with 35 to 40 kg/m 2 . METHODS: The prospective observational Fetal MMC Consortium registry sponsored by the North American Fetal Therapy Network was used to extract deidentified “maternal complication” and “fetal/neonatal complication” data sets, corresponding to patients with complete entries related to maternal or fetal/neonatal complications, respectively. Demographics, clinical characteristics, and complications were recorded. Propensity score matching was conducted with a 2:1 algorithm, and outcomes were compared between patients with BMI < 35 kg/m 2 and those with BMI 35 to 40 kg/m 2 . RESULTS: Propensity score matching resulted in 156 patients with BMI < 35 kg/m 2 and 78 patients with BMI 35 to 40 kg/m 2 in the “maternal complication” data set, and 130 patients with BMI < 35 kg/m 2 and 65 patients with BMI 35 to 40 kg/m 2 in the “fetal/neonatal complication” data set. No significant differences in the median number of maternal (2.0 vs 2.0; P = .257) or median number of fetal/neonatal (1.0 vs 1.0; P = .409) complications were observed between the 2 cohorts. Furthermore, prematurity rates did not differ significantly between the BMI < 35 and BMI 35 to 40 cohorts. CONCLUSION: Maternal-fetal surgery for open neural tube defect closure is not associated with increased risks among patients with a maternal BMI of 35 to 40 kg/m 2 . Extending the initial inclusion criteria for prenatal MMC closure has the potential to expand access to patients with a higher risk for open neural tube defects.

Abstract Objective In utero fetal spina bifida repair decreases the risk for cerebrospinal fluid (CSF) diversion including ventriculoperitoneal (VP) shunt placement, reverses hindbrain herniation, and improves motor function with a higher likelihood of independent ambulation. Unfortunately, in utero surgery can be complicated by preterm delivery. The goal of this study was to compare pregnancy and neonatal outcomes between individuals who delivered very preterm, and those who delivered later in gestation following in utero spina bifida repair. Methods Data from the North American Fetal Therapy Network Fetal Myelomeningocele Consortium Registry collected from 2011 to 2024 were analyzed. Three cohorts of patients were categorized by gestational age at delivery and compared: <30 weeks, 30–34 weeks, and >34 weeks. Comparisons between groups for maternal and delivery outcomes were completed for the entire cohort and then analyzed for those with available CSF diversion data up to 1 year of life. Chi‐square or Fisher's exact tests were used to compare categorical variables, and Kruskal–Wallis tests were used to determine if there are significant differences between the distributions of the three groups. A p ‐value <0.05 was considered significant. Results A total of 1213 patients were analyzed (<30 weeks, n = 111 [9.2%]; 30–34 weeks, n = 323 [26.6%]; >34 weeks, n = 779 [64.2%]). Overall fetal and neonatal mortality was 2.2%, 85% of which occurred in the <30‐week cohort, where perinatal mortality was 21%. Latency from fetal surgery to delivery averaged 2.1 weeks for the <30‐week group. Rates of abruption, chorioamnionitis, and spontaneous labor were higher in the <30‐week group compared to later gestational age cohorts. Neonatal morbidity was also significantly higher in the <30‐week cohort for sepsis, apnea, respiratory distress, patent ductus arteriosus, intraventricular hemorrhage, and periventricular leukomalacia in the <30‐week cohort. CSF diversion data were available for 677 neonates (<30 weeks, n = 53; 30–34 weeks, n = 186; >34 weeks, n = 438). There was no significant difference in VP shunt placement between the different gestational age groups. Conclusion Very preterm birth following in utero spina bifida repair results in significant perinatal mortality and neonatal morbidity. Delivery prior to 30 weeks of gestation occurs in 9% of patients after in utero spina bifida repair, resulting in a 21% perinatal mortality rate. However, even among those who delivered very preterm, a reduction in VP shunt rates, a benefit of in utero repair, appears to be preserved. Further data are warranted to assess the impact of prematurity following in utero surgery on ambulation and developmental outcomes.

ObjectivesFetal growth restriction (FGR) is commonly associated with placental dysfunction, increasing perinatal morbidity and mortality. Visualizing placental vessels in utero would be advantageous for identifying functional FGR cause and determining proper management strategies. We aimed to utilize high‐sensitivity ultrasound microvessel imaging (HUMI) for quantifying placental vessel density (VD) in pregnancies diagnosed with FGR.MethodsThis pilot case–control study enrolled subjects in the third trimester with a diagnosis of FGR (n = 40) and gestational age‐matched controls with normal fetal growth (n = 20) at a 2:1 ratio, respectively. The Verasonics Vantage ultrasound system was used to perform HUMI on each participant at one timepoint. Scanning involved randomized singular value decomposition‐based clutter filtering to identify the villous tree, followed by step‐by‐step scanning to acquire 3‐dimensional‐like data. Mean VD was calculated from three ultrasound measurements per subject. Additional clinical and pathology data were also collected and compared.ResultsSixteen participants were utilized to establish the scanning protocol and 2 met exclusion criteria at delivery. Thus, VD was successfully measured on 42 pregnancies scanned at 35 weeks 5 days on average. In FGR (n = 24), placental VD was significantly reduced compared to controls (P < .01). VD measures were as good at predicting FGR as systolic/diastolic (S/D) ratios (area under the curve 0.86 versus 0.80). In a smaller cohort, VD in placentas with a diagnosis of inflammatory villitis (n = 10) by histology showed an increase in VD compared to those without inflammation (P = .01). Low VD was correlated with increased S/D ratios (P = .03).ConclusionsHUMI is useful for identifying altered placental vascularization in utero for FGR. VD may be a valuable indicator for placental health and could lead to improved risk stratification methods considering underlying biology.

The fetal sheep model has been widely used in fetal therapy research. However, there is a significant degree of variability among published normal values. Our study aimed to evaluate the literature available on normal values for hemodynamics, blood gases, and acid-base status in the sheep fetus and to determine the best possible estimation of such physiologic values. We conducted a systematic review with a comprehensive search of several databases. We included 189 articles in the database and over 2,800 sheep fetuses. Analysis revealed a mean umbilical blood flow of 202 mL/kg/min (95% CI: 182 to 223); mean arterial pCO2 of 49.8 mm Hg (95% CI: 49.2 to 50.3); mean arterial pO2 of 22.3 mm Hg (95% CI: 21.9 to 22.7); mean arterial pH of 7.35 (95% CI: 7.3487 to 7.3562); and mean arterial oxygen saturation of 59.8 (95% CI; 58 to 61.7). Our findings were punctuated by a high heterogeneity, for which we conducted several subanalyses. The results showed high heterogeneity and small study effect in the literature available and provided our best assessment of relevant variables on normal hemodynamics, blood gases, and acid-base status in the fetus after using strategies to mitigate the risk of bias present in the literature.