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Umbilical Cord

Anatomy and Physiology · NLM MeSH · updated 2026-10-31 · version 1

Citations verified against PubMedNot yet clinician-reviewed10 referencesApproximately 6 min read

The flexible rope-like structure that connects a developing fetus to the placenta in mammals.

Table of Contents

1. Definition2. Research landscape3. Reading the evidence4. Open-access studies5. Key reviews6. References7. About this article

Definition and research guide

This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.

Content available: 4 complete abstracts (1,223 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.

Definition

The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus.

Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.

Also known as: Cords, Umbilical; Cord, Umbilical; Umbilical Cords.

Where it fits in the MeSH classification

Broader topics
Fetus
Narrower topics
Umbilical Arteries; Umbilical Veins

Related concepts

  • Fetus
  • Placenta

Research landscape

PubMed indexes 31,109 records tagged with the MeSH heading “Umbilical Cord” (counts retrieved 2026-10-31). 4,070 of them (13.1%) were published from 2020 onward, and the busiest period so far is through 1999 with 13,542 records.

Reviews account for 1,442 records (4.6%) and meta-analyses for 128. Randomized controlled trials number 661 (2.1%) as a share of all records on the topic.

PubMed records by publication periodthrough 1999: 13,542 records; 2000-2009: 7,629 records; 2010-2019: 5,868 records; 2020 onward: 4,070 records13,542through 19997,6292000-20095,8682010-20194,0702020 onward
Records in PubMed indexed with this heading, by publication period. Real counts from NCBI E-utilities; the final period covers only part of the current year. Volume reflects how much has been published, not how strong the evidence is.
Show the data
PeriodRecords
through 199913,542
2000-20097,629
2010-20195,868
2020 onward4,070
Share of records by publication typeReviews: 4.6 percent; Meta-analyses: 0.4 percent; Randomized controlled trials: 2.1 percentReviews4.6% (1,442)Meta-analyses0.4% (128)Randomized controlled trials2.1% (661)
Share of all PubMed records on this heading that carry each publication type. Types overlap with other records, so the shares do not sum to 100%.
Publication-type chart data
Publication types among 31,109 PubMed records
TypeRecordsShare
Reviews1,4424.6%
Meta-analyses1280.4%
Randomized controlled trials6612.1%

Method: PubMed query "Umbilical Cord"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.

Reading the evidence in anatomy and physiology

Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.

Evidence from open-access studies

These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.

Study comparison — selected abstracts, not a systematic review
Study / authorsYearSource label / designEurope PMC citationsLicence / source
Clinical investigation on nebulized human umbilical cord MSC-derived extracellular vesicles for pulmonary fibrosis treatment
Li M, Huang H, Wei X, Li H, Li J, Xie B, et al.
2025Randomized controlled trial
Design not recorded in structured metadata
72cc by
PMID 40461474 · DOI · PMC12134356
Human adipose and umbilical cord mesenchymal stem cell-derived extracellular vesicles mitigate photoaging via TIMP1/Notch1
Zhang H, Xiao X, Wang L, Shi X, Fu N, Wang S, et al.
2024Research article
Design not recorded in structured metadata
72cc by
PMID 39472581 · DOI · PMC11522688
Injection of human umbilical cord mesenchymal stem cells exosomes for the treatment of knee osteoarthritis: from preclinical to clinical research
Wang Y, Kong Y, Du J, Qi L, Liu M, Xie S, et al.
2025Randomized controlled trial
Design not recorded in structured metadata
45cc by
PMID 40500748 · DOI · PMC12153132
Apgar Score Plus Umbilical Artery pH and Adverse Neonatal Outcomes in Very Preterm Infants
Ehrhardt H, Behboodi S, Maier RF, Aubert AM, Ådén U, Staude B, et al.
2026Research article
Design not recorded in structured metadata
2cc by
PMID 41649815 · DOI · PMC12881985

Clinical investigation on nebulized human umbilical cord MSC-derived extracellular vesicles for pulmonary fibrosis treatment [1]

Randomized controlled trial Li M, Huang H, Wei X, Li H, Li J, Xie B, et al. · · 2025 · cited 72 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are recognized as a promising strategy for cell-free therapy, however, their therapeutic role in pulmonary fibrosis remains unrevealed.
Closing excerpt
These findings suggest that nebulized hUCMSC-EVs could be used as a promising therapeutic strategy for treating pulmonary fibrosis diseases.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (237 words)

Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are recognized as a promising strategy for cell-free therapy, however, their therapeutic role in pulmonary fibrosis remains unrevealed. Here, we report the safety and efficacy of MSC-EVs from human umbilical cord (hUCMSC-EVs) evaluated in mouse models and pulmonary fibrosis patients. We established a rigorous system to produce high-quality of hUCMSC-EVs, characterized by miRNA, protein, and metabolite profiles. When administered via nebulization, hUCMSC-EVs predominantly accumulated in murine lungs and ameliorated bleomycin-induced pulmonary fibrosis, with increased survival rate (from 20% to 80%), restored lung volume, and attenuated injury severity accompanied by elevated oxyhemoglobin saturation and improved pulmonary function evaluations. We performed a phase l clinical trial involving twenty-four patients in a randomized, single-blind, and placebo-controlled study to treat pulmonary fibrosis (MR-46-22-004531, ChiCTR2300075466). All participants tolerated the nebulized hUCMSC-EVs well, with no serious adverse events. Patients receiving the combined therapy of nebulized hUCMSC-EVs and routine treatment demonstrated significant improvements in both lung function indices (forced vital capacity and maximal voluntary ventilation) and respiratory health status (as measured by the Saint George's Respiratory Questionnaire and Leicester Cough Questionnaire. Overall, patients upon the additional therapy with nebulized hUCMSC-EVs gained significant benefits compared with those accepted only routine treatment. Remarkably, two patients with advanced post-inflammatory pulmonary fibrosis exhibited clinically significant regression on serial CT scans after hUCMSC-EVs therapy. These findings suggest that nebulized hUCMSC-EVs could be used as a promising therapeutic strategy for treating pulmonary fibrosis diseases.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40461474 · DOI · PMC12134356

Human adipose and umbilical cord mesenchymal stem cell-derived extracellular vesicles mitigate photoaging via TIMP1/Notch1 [2]

Research article Zhang H, Xiao X, Wang L, Shi X, Fu N, Wang S, et al. · · 2024 · cited 72 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
UVB radiation induces oxidative stress, DNA damage, and inflammation, leading to skin wrinkling, compromised barrier function, and an increased risk of carcinogenesis.
Closing excerpt
Collectively, our data suggests that both AMSC-EV and HUMSC-EV attenuate skin photoaging through TIMP1/Notch1.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (240 words)

UVB radiation induces oxidative stress, DNA damage, and inflammation, leading to skin wrinkling, compromised barrier function, and an increased risk of carcinogenesis. Addressing or preventing photoaging may offer a promising therapeutic avenue for these conditions. Recent research indicated that mesenchymal stem cells (MSCs) exhibit significant therapeutic potential for various skin diseases. Given that extracellular vesicles (EV) can deliver diverse cargo to recipient cells and elicit similar therapeutic effects, we investigated the roles and underlying mechanisms of both adipose-derived MSC-derived EV (AMSC-EV) and umbilical cord-derived MSC-derived EV (HUMSC-EV) in photoaging. Our findings indicated that in vivo, treatment with AMSC-EV and HUMSC-EV resulted in improvements in wrinkles and skin hydration while also mitigating skin inflammation and thickness alterations in both the epidermis and dermis. Additionally, in vitro studies using human keratinocytes (HaCaTs), human dermal fibroblast cells (HDFs), and T-Skin models revealed that AMSC-EV and HUMSC-EV attenuated senescence, reduced levels of reactive oxygen species (ROS) and DNA damage, and alleviated inflammation induced by UVB. Furthermore, EV treatment enhanced cell viability and migration capacity in the epidermis and promoted extracellular matrix (ECM) remodeling in the dermis in photoaged cell models. Mechanistically, proteomics results showed that TIMP1 was highly expressed in both AMSC-EV and HUMSC-EV and could exert similar effects as MSC-EV. In addition, we found that EV and TIMP1 could inhibit Notch1 and downstream targets Hes1, P16, P21, and P53. Collectively, our data suggests that both AMSC-EV and HUMSC-EV attenuate skin photoaging through TIMP1/Notch1.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 39472581 · DOI · PMC11522688

Injection of human umbilical cord mesenchymal stem cells exosomes for the treatment of knee osteoarthritis: from preclinical to clinical research [3]

Randomized controlled trial Wang Y, Kong Y, Du J, Qi L, Liu M, Xie S, et al. · · 2025 · cited 45 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
BackgroundBackground: Exosomes (Exos) derived from mesenchymal stem cells (MSCs) share similar biological functions with MSCs but are more stable under various pathophysiological conditions, with a lower risk of immune rejection.
Closing excerpt
cn/login# .
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (249 words)

BackgroundBackground: Exosomes (Exos) derived from mesenchymal stem cells (MSCs) share similar biological functions with MSCs but are more stable under various pathophysiological conditions, with a lower risk of immune rejection. Human umbilical cord mesenchymal stem cells (hUC-MSCs) are a promising source of MSC-derived exosomes (MSC-Exos), particularly for the treatment of osteoarthritis (OA), a degenerative joint disease characterized by inflammation and cartilage damage.MethodsIn this study, we conducted in vitro experiments on mouse articular chondrocytes and treated mouse OA models with hUC-MSCs-Exos. To validate the results of hUC-MSCs-Exos in humans, a randomized, double-blind, ascending dose study was conducted to investigate the safety and efficacy of hUC-MSCs-Exos in the treatment of OA, and human chondrocyte toxicity experiments were conducted prior to the clinical trial.ResultsIn this study, we successfully extracted hUC-MSCs and verified their multilineage differentiation ability in different culture media. We then verified the Exos morphology and the expression of CD9, CD63, TSG1, and CALN. In preclinical experiments in vitro and in vivo, we verified that hUC-MSC- Exos can reduce the inflammatory response of articular cartilage and promote its regeneration. Finally, clinical experiments confirmed that hUC-MSC- Exos injection treatment of OA patients did not cause any adverse consequences, and a certain degree of effectiveness was found in the comparison of clinical scores and MRI examinations before and after treatment.ConclusionsThis study shows that hUC-MSC-derived exosomes effectively reduce inflammation and promote cartilage regeneration in osteoarthritis, with demonstrated safety and efficacy in both preclinical and clinical settings.Trial registrationTrial No.MR-13-24-017929. Registered 11 February 2023, https://medicalresearch.org.cn/login# .

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40500748 · DOI · PMC12153132

Apgar Score Plus Umbilical Artery pH and Adverse Neonatal Outcomes in Very Preterm Infants [4]

Research article Ehrhardt H, Behboodi S, Maier RF, Aubert AM, Ådén U, Staude B, et al. · · 2026 · cited 2 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
ImportanceThe Apgar score, the first clinical assessment to direct measures to stabilize newborn infants, is also used for risk assessment.
Closing excerpt
These results highlight the importance of exploring the associations of early markers of risk with neonatal mortality and key neonatal morbidities separately.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (497 words)

ImportanceThe Apgar score, the first clinical assessment to direct measures to stabilize newborn infants, is also used for risk assessment. Its accuracy in estimating outcomes remains poor among very preterm (VPT) infants.ObjectiveTo assess the utility of the combined 5-minute Apgar score and umbilical artery pH (UA-pH) for estimating risks of mortality and severe neonatal morbidity among VPT infants.Design, setting, and participantsThis cohort study (Effective Perinatal Intensive Care in Europe [EPICE]) analyzed infants born at less than 32 weeks' gestation between April 2011 and September 2012 across 11 European countries. All liveborn VPT infants with Apgar scores and UA-pH data were included. Data were analyzed between February and December 2025.ExposuresApgar score at 5 minutes and UA-pH. The Apgar score was classified as lower than 7 and 7 or higher, and the UA-pH values were categorized as low (Main outcomes and measuresCombined outcome of mortality and/or any adverse morbidity (intraventricular hemorrhage [IVH] >grade 2, cystic periventricular leukomalacia, moderate or severe bronchopulmonary dysplasia [BPD], retinopathy of prematurity ≥stage 2, and necrotizing enterocolitis). Modified Poisson regression was used to estimate relative risks (RRs) between the exposure and the combined mortality and morbidity outcome and 3 individual components: mortality, IVH, and BPD. Models were adjusted for perinatal variables associated with Apgar score and UA-pH and adverse neonatal outcomes.ResultsOf 7900 liveborn infants in the EPICE cohort, 4174 (52.8%) had information on Apgar score and UA-pH. These infants included 2249 males (53.9%) and had a median [IQR] gestational age of 29.9 [27.9-31.0] weeks and median [IQR] birth weight of 1240 [960-1520] g. A total of 367 infants (8.8%) had an Apgar score 7 or higher but a low UA-pH, 558 (13.4%) had an Apgar score lower than 7 but a normal UA-pH, and 196 (4.7%) had an Apgar score lower than 7 and a low UA-pH. Infants with an Apgar score lower than 7 had a higher frequency of the combined outcome among those with a normal UA-pH (270 [48.4%] vs 596 [19.5%]) and a low UA-pH (108 [55.1%] vs 596 [19.5%]), with similar adjusted RRs (ARRs; low: 1.4 [95% CI, 1.2-1.7]; normal: 1.4 [95% CI, 1.3-1.6]). For mortality risk, associations were robust for an Apgar score lower than 7 and a low UA-pH (ARR, 2.4; 95% CI, 1.7-3.3) and absent with an Apgar score of 7 or higher and a low UA-pH (ARR, 1.2; 95% CI, 0.8-1.8). IVH risk was increased in all 3 subcategories, including an Apgar score of 7 or higher with a low UA-pH (ARR, 2.0; 95% CI, 1.3-3.0). BPD risk was associated only with an Apgar score lower than 7 and a normal UA-pH (ARR, 1.4; 95% CI, 1.2-1.7).Conclusions and relevanceIn this cohort study of VPT infants, combining information on UA-pH with the 5-minute Apgar score was associated with improved accuracy in estimating the risk of some adverse outcomes-notably mortality and IVH, which occurred soon after birth. These results highlight the importance of exploring the associations of early markers of risk with neonatal mortality and key neonatal morbidities separately.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41649815 · DOI · PMC12881985

Key reviews and meta-analyses

The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.

  • Research article Human umbilical cord mesenchymal stem cells: a new era for stem cell therapy [5]
    Ding DC, Chang YH, Shyu WC, Lin SZ · Cell Transplant · 2015 · cited 443 times (Europe PMC)
  • Research article Delayed vs early umbilical cord clamping for preterm infants: a systematic review and meta-analysis [6]
    Fogarty M, Osborn DA, Askie L, Seidler AL, Hunter K, Lui K, et al. · Am J Obstet Gynecol · 2018 · cited 344 times (Europe PMC)
  • Research article Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes [7]
    McDonald SJ, Middleton P, Dowswell T, Morris PS · Cochrane Database Syst Rev · 2013 · cited 216 times (Europe PMC)
  • Research article Late vs early clamping of the umbilical cord in full-term neonates: systematic review and meta-analysis of controlled trials [8]
    Hutton EK, Hassan ES · JAMA · 2007 · cited 216 times (Europe PMC)
  • Research article Human umbilical cord mesenchymal stem cells: an overview of their potential in cell-based therapy [9]
    Li T, Xia M, Gao Y, Chen Y, Xu Y · Expert Opin Biol Ther · 2015 · cited 192 times (Europe PMC)
  • Research article ISUOG Practice Guidelines (updated): use of Doppler velocimetry in obstetrics [10]
    Bhide A, Acharya G, Baschat A, Bilardo CM, Brezinka C, Cafici D, et al. · Ultrasound Obstet Gynecol · 2021 · cited 180 times (Europe PMC)

References

  1. Li M, Huang H, Wei X, Li H, Li J, Xie B, et al.. Clinical investigation on nebulized human umbilical cord MSC-derived extracellular vesicles for pulmonary fibrosis treatment. . 2025. PMID 40461474 · DOI · PMC12134356
  2. Zhang H, Xiao X, Wang L, Shi X, Fu N, Wang S, et al.. Human adipose and umbilical cord mesenchymal stem cell-derived extracellular vesicles mitigate photoaging via TIMP1/Notch1. . 2024. PMID 39472581 · DOI · PMC11522688
  3. Wang Y, Kong Y, Du J, Qi L, Liu M, Xie S, et al.. Injection of human umbilical cord mesenchymal stem cells exosomes for the treatment of knee osteoarthritis: from preclinical to clinical research. . 2025. PMID 40500748 · DOI · PMC12153132
  4. Ehrhardt H, Behboodi S, Maier RF, Aubert AM, Ådén U, Staude B, et al.. Apgar Score Plus Umbilical Artery pH and Adverse Neonatal Outcomes in Very Preterm Infants. . 2026. PMID 41649815 · DOI · PMC12881985
  5. Ding DC, Chang YH, Shyu WC, Lin SZ. Human umbilical cord mesenchymal stem cells: a new era for stem cell therapy. Cell Transplant. 2015. PMID 25622293 · DOI
  6. Fogarty M, Osborn DA, Askie L, Seidler AL, Hunter K, Lui K, et al.. Delayed vs early umbilical cord clamping for preterm infants: a systematic review and meta-analysis. Am J Obstet Gynecol. 2018. PMID 29097178 · DOI
  7. McDonald SJ, Middleton P, Dowswell T, Morris PS. Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes. Cochrane Database Syst Rev. 2013. PMID 23843134 · DOI · PMC6544813
  8. Hutton EK, Hassan ES. Late vs early clamping of the umbilical cord in full-term neonates: systematic review and meta-analysis of controlled trials. JAMA. 2007. PMID 17374818 · DOI
  9. Li T, Xia M, Gao Y, Chen Y, Xu Y. Human umbilical cord mesenchymal stem cells: an overview of their potential in cell-based therapy. Expert Opin Biol Ther. 2015. PMID 26067213 · DOI
  10. Bhide A, Acharya G, Baschat A, Bilardo CM, Brezinka C, Cafici D, et al.. ISUOG Practice Guidelines (updated): use of Doppler velocimetry in obstetrics. Ultrasound Obstet Gynecol. 2021. PMID 34278615 · DOI

About this article

Sources
NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
Verification
Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
Review state
automated source verified; no human expert review has been recorded yet.
Version
1, last updated 2026-10-31.

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All 542 articles in Anatomy and Physiology →

At a glance

31,109
PubMed records on this heading
13%
published since 2020
1,442
review articles
661
randomized trials
10
verified references below

Counts come from PubMed on 2026-10-31; they show how much has been written, not how strong the evidence is.

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  • PlacentationAnatomy and Physiology
  • Spermatic CordAnatomy and Physiology

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