Therapeutic trials of maternal position therapy are needed to clarify the causes of abnormal maternal hemodynamic profiles and reduced umbilical vein flow in fetal growth restriction
To the Editor,
I congratulate Dr. Daniele Farsetti and his colleagues for their recent intriguing contribution to the Journal of Perinatal Medicine, “Umbilical venous flow and maternal hemodynamics as predictors of impaired fetal growth in gestational diabetes” [1]. This new study, which builds upon their already well-developed concept of the “cardiac-fetal-placental unit” [2] shows that in patients with gestational diabetes, reduced umbilical venous flow (UV-Q) percentiles and low cardiac output (CO)/high systemic vascular resistance (SVR) maternal hemodynamic profiles are associated with reduced future birth weights. I wish to point out, however, that the explanation of these thought-provoking associations remains unclear for the following reasons:
Maternal hemodynamic profiles are whole-body assessments of global maternal hemodynamic function and are therefore relatively insensitive to local and possibly severe reductions of placental perfusion and fetal oxygenation due to elevated uterine venous pressure [3].
Chronic and recurrent obstruction of maternal venous return may periodically reduce maternal CO, thereby activating the sympathetic nervous system and the renin angiotensin aldosterone system, which may then create a persistent “low CO/high SVR” hemodynamic profile [3].
UV-Q may decrease quickly and dramatically due to changes in maternal position which increase intervillous space pressure – which then produces limited “sluice flow” within the fetal vessels of the chorionic villi [3].
A reduced UV-Q percentile at 28–32 weeks of gestation might be the result of previous fetal injury, as well as a cause of reduced future growth since an already-injured fetus may not grow as well as an uninjured one and may therefore not need as much oxygen to support its already limited growth potential.
Despite possibility 4), I believe that reduced UV-Q is, in fact, an important and common cause of decreased fetal growth and that obstruction of uterine venous return may be an important cause of both reduced UV-Q and reduced uteroplacental perfusion [3].
One way to clarify the causes and significance of both abnormal hemodynamic profiles and reduced UV-Q would be to perform randomized controlled trials of cardiac output-guided maternal positioning to systematically prevent obstruction of maternal and uterine venous return during the second half of gestation. If such “position therapy” produced parallel improvement of a) hemodynamic profiles, b) UV-Q percentiles and c) fetal growth, this result would strengthen the theory that obstruction of uterine venous return at the inferior vena cava is a preventable cause of fetal growth restriction. Investigation of this possibility would also do much to refine and clarify the valuable concept of the cardiac-fetal-placental unit [2], 4].
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Research ethics: Not applicable.
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Informed consent: Not applicable.
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Author contributions: The author has accepted responsibility for the entire content of this manuscript and approved its submission. November 29, 2025.
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Use of Large Language Models, AI and Machine Learning Tools: The AI function of the Google Chrome browser was used to search for relevant references, which were then individually reviewed by the author. No LLM was used for the writing of the manuscript.
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Conflict of interest: The author knows and has consulted and corresponded extensively with Markus Osypka, PhD, owner of Osypka Medical, Inc. which manufactures and sells the Electrical Cardiometry system of impedance cardiography, which the author used in his research at UCSD from 2008 until 2015. The author does not have and has never had any business or financial relationship with Dr. Osypka.
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Research funding: None declared.
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Data availability: Not applicable.
References
1. Farsetti, D, Nardini, S, Maffi, L, Gagliardi, G, Frantellizzi, R, Pometti, F, et al.. Umbilical venous flow and maternal hemodynamics as predictors of impaired fetal growth in gestational diabetes: a prospective study. J Perinat Med 2026;54:51–60. https://doi.org/10.1515/jpm-2025-0353.Search in Google Scholar PubMed
2. Valensise, H, Farsetti, D, Pometti, F, Vasapollo, B, Novelli, GP, Lees, C. The cardiac-fetal-placental unit: fetal umbilical vein flow rate is linked to the maternal cardiac profile in fetal growth restriction. Am J Obstet Gynecol 2023;228:222.e1–222.e12. https://doi.org/10.1016/j.ajog.2022.08.004.Search in Google Scholar PubMed
3. Archer, TL. Cardiac output-guided maternal positioning may protect the fetal oxygen supply and thereby reduce pregnancy complications. J Perinat Med 2026;54:23–41. https://doi.org/10.1515/jpm-2025-0333.Search in Google Scholar PubMed
4. Archer, TL. Threats to fetal, placental and myometrial oxygenation: a unified hemodynamic approach. Cham: Springer; 2024.10.1007/978-3-031-60364-8Search in Google Scholar
© 2026 the author(s), published by De Gruyter, Berlin/Boston
This work is licensed under the Creative Commons Attribution 4.0 International License.
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- Letters to the Editor
- Therapeutic trials of maternal position therapy are needed to clarify the causes of abnormal maternal hemodynamic profiles and reduced umbilical vein flow in fetal growth restriction
- Let’s use diverse technologies to assess maternal hemodynamics-- both before and during labor and to both predict and prevent bad outcomes!
- Corrigendum
- The FAIR framework: ethical hybrid peer review
Articles in the same Issue
- Frontmatter
- Commentary
- The IAPM New Delhi 2025 Declaration on Svadharma and Professional Responsibility
- Reviews
- The use of laser therapy in fetal medicine: a narrative review
- Nutriepigenomics in perinatal medicine: maternal nutrition as a modulator of fetal gene expression and long-term health
- Original Articles – Obstetrics
- Community births in the United States, 2016–2024: post-pandemic patterns across racial and ethnic groups
- Preeclampsia is associated with increased NT-proBNP and altered lipid profiles in umbilical cord blood: a propensity score-matched analysis
- Ureaplasma parvum detected in umbilical cord tissues diagnosed with funisitis associated with adverse pregnancy outcomes and neonatal pneumonia
- Implementation of a universal low-dose aspirin protocol for the prevention of preeclampsia in a federally qualified health center
- Comparative evaluation of manual and VOCAL methods for amniotic sac volume measurement in early pregnancy
- McDonald vs. Shirodkar cerclage for the prevention of preterm birth in patients with obesity
- The incidence and outcomes of perinatal asphyxia in spontaneous extreme preterm birth: a retrospective cohort study
- Comparative effectiveness of oxytocin, carbetocin, and tranexamic acid for postpartum hemorrhage prevention in cesarean deliveries: a prospective cohort analysis
- Risk factors for primary cesarean delivery in women with gestational diabetes mellitus: a predictive model for clinical risk assessment
- Evaluation of Doppler parameters and obstetric outcomes in intrahepatic cholestasis of pregnancy
- Diagnostic yield and clinical impact of prenatal whole exome sequencing (WES) – four-year single center experience
- Associations between previous cesarean section and maternal and neonatal complications: the modification of long inter-pregnancy interval
- Maternal and neonatal outcomes of ultrasound-guided percutaneous nephrostomy for symptomatic hydronephrosis in pregnancy: a retrospective cohort study
- Original Articles – Fetus
- Abnormal Doppler and perinatal outcomes according to the placental lesions of maternal and fetal vascular malperfusion in preterm fetal growth restriction
- The additional value of fetal MRI to ultrasonography in prenatal diagnosis: an evaluation based on postnatal confirmation
- The fetal exposome and preterm birth: a systematic synthesis of environmental exposures and multi-omics evidence
- Original Articles – Neonates
- Pregnancy-associated anemia and its effects in term neonates
- Longitudinal changes of left ventricular hypoplasia and ventricular disproportion in congenital diaphragmatic hernia neonates
- Outcomes in early term neonates requiring extracorporeal membrane oxygenation
- Letters to the Editor
- Therapeutic trials of maternal position therapy are needed to clarify the causes of abnormal maternal hemodynamic profiles and reduced umbilical vein flow in fetal growth restriction
- Let’s use diverse technologies to assess maternal hemodynamics-- both before and during labor and to both predict and prevent bad outcomes!
- Corrigendum
- The FAIR framework: ethical hybrid peer review
