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Jaeger KM, Nissen M, Rahm S, Titzmann A, Fasching PA, Beilner J, Eskofier BM, Leutheuser H. Power-MF: robust fetal QRS detection from non-invasive fetal electrocardiogram recordings. Physiol Meas 2024; 45:055009. [PMID: 38722552 DOI: 10.1088/1361-6579/ad4952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 05/09/2024] [Indexed: 05/22/2024]
Abstract
Objective.Perinatal asphyxia poses a significant risk to neonatal health, necessitating accurate fetal heart rate monitoring for effective detection and management. The current gold standard, cardiotocography, has inherent limitations, highlighting the need for alternative approaches. The emerging technology of non-invasive fetal electrocardiography shows promise as a new sensing technology for fetal cardiac activity, offering potential advancements in the detection and management of perinatal asphyxia. Although algorithms for fetal QRS detection have been developed in the past, only a few of them demonstrate accurate performance in the presence of noise and artifacts.Approach.In this work, we proposePower-MF, a new algorithm for fetal QRS detection combining power spectral density and matched filter techniques. We benchmarkPower-MFagainst three open-source algorithms on two recently published datasets (Abdominal and Direct Fetal ECG Database: ADFECG, subsets B1 Pregnancy and B2 Labour; Non-invasive Multimodal Foetal ECG-Doppler Dataset for Antenatal Cardiology Research: NInFEA).Main results.Our results show thatPower-MFoutperforms state-of-the-art algorithms on ADFECG (B1 Pregnancy: 99.5% ± 0.5% F1-score, B2 Labour: 98.0% ± 3.0% F1-score) and on NInFEA in three of six electrode configurations by being more robust against noise.Significance.Through this work, we contribute to improving the accuracy and reliability of fetal cardiac monitoring, an essential step toward early detection of perinatal asphyxia with the long-term goal of reducing costs and making prenatal care more accessible.
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Affiliation(s)
- Katharina M Jaeger
- Friedrich-Alexander-Universitat Erlangen-Nürnberg, Machine Learning and Data Analytics Lab, Carl-Thiersch-Straße 2b, 91052 Erlangen, Germany
| | - Michael Nissen
- Friedrich-Alexander-Universitat Erlangen-Nürnberg, Machine Learning and Data Analytics Lab, Carl-Thiersch-Straße 2b, 91052 Erlangen, Germany
| | - Simone Rahm
- Friedrich-Alexander-Universitat Erlangen-Nürnberg, Machine Learning and Data Analytics Lab, Carl-Thiersch-Straße 2b, 91052 Erlangen, Germany
| | - Adriana Titzmann
- Department of Gynecology and Obstetrics, Erlangen University Hospital, Universitätsstraße 21-23, 91054 Erlangen, Germany
| | - Peter A Fasching
- Department of Gynecology and Obstetrics, Erlangen University Hospital, Universitätsstraße 21-23, 91054 Erlangen, Germany
| | - Janina Beilner
- Friedrich-Alexander-Universitat Erlangen-Nürnberg, Machine Learning and Data Analytics Lab, Carl-Thiersch-Straße 2b, 91052 Erlangen, Germany
| | - Bjoern M Eskofier
- Friedrich-Alexander-Universitat Erlangen-Nürnberg, Machine Learning and Data Analytics Lab, Carl-Thiersch-Straße 2b, 91052 Erlangen, Germany
- Translational Digital Health Group, Institute of AI for Health, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany
| | - Heike Leutheuser
- Friedrich-Alexander-Universitat Erlangen-Nürnberg, Machine Learning and Data Analytics Lab, Carl-Thiersch-Straße 2b, 91052 Erlangen, Germany
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Gonzalez M, Hill M, Cohen WR. Performance of a Maternal Abdominal Surface Electrode System for Fetal Heart Rate and Uterine Contraction Monitoring from 34 to 37 Weeks. Am J Perinatol 2024; 41:263-269. [PMID: 34666382 DOI: 10.1055/a-1673-1765] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The objective of this study was to compare performance of a maternal surface electrode patch with ultrasound- and tocodynamometer-based monitoring to detect fetal heart rate and uterine contractility in late preterm labors. STUDY DESIGN Thirty women between 340/7 and 366/7 weeks' gestation were monitored simultaneously with a Doppler/tocodynamometer system and a wireless fetal-maternal abdominal surface electrode system. Fetal and maternal heart rate and uterine contraction data from both systems were compared. Reliability was measured by the success rate and percent agreement. Deming regression and Bland-Altman analysis estimated the concordance between the systems. Uterine contractions were assessed by visual interpretation of monitor tracings. RESULTS The success rate for the surface electrode system was 89.5% (95% confidence interval [CI], 85.7-93.3), and for ultrasound it was 88.4% (95% CI, 84.9-91.9; p = 0.73), with a percent agreement of 88.1% (95% CI, 84.2-92.8). Results were uninfluenced by the patients' body mass. The mean Deming slope was 1 and the y-intercept was -3.0 beats per minute (bpm). Bland-Altman plots also showed a close relationship between the methods, with limits of agreement less than 10 bpm. The percent agreement for maternal heart rate was 98.2% (95% CI, 97.4-98.8), and for uterine contraction detection it was 89.5% (95% CI, 85.5-93.4). CONCLUSION Fetal heart rate and uterine contraction monitoring at 340/7 to 366/7 weeks using abdominal surface electrodes was not inferior to Doppler ultrasound/tocodynamometry for fetal-maternal assessment. REGISTRATION clinicaltrials.gov/February 20, 2017/identifier NCT03057275. KEY POINTS · Monitoring the preterm fetal heart rate with surface electrodes is feasible.. · Preterm contractions can be monitored with surface electrodes.. · The technique was noninferior to standard external monitors..
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Affiliation(s)
- Maritza Gonzalez
- Department of Obstetrics and Gynecology, University of Arizona College of Medicine, Tucson, Arizona
| | - Meghan Hill
- Department of Obstetrics and Gynecology, University of Arizona College of Medicine, Tucson, Arizona
| | - Wayne R Cohen
- Department of Obstetrics and Gynecology, University of Arizona College of Medicine, Tucson, Arizona
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Coddington R, Scarf V, Fox D. Australian women's experiences of wearing a non-invasive fetal electrocardiography (NIFECG) device during labour. Women Birth 2023; 36:546-551. [PMID: 36925403 DOI: 10.1016/j.wombi.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 03/06/2023] [Accepted: 03/08/2023] [Indexed: 03/15/2023]
Abstract
BACKGROUND Continuous electronic fetal monitoring devices can restrict women's freedom of movement and choice of positioning during labour and birth. Despite the use of continuous electronic fetal monitoring for the past 50 years, little attention has been paid to women's experiences of wearing different fetal monitoring devices in labour. AIM To explore women's views and experiences of wearing a beltless continuous electronic fetal monitoring device, the non-invasive fetal electrocardiogram during labour. METHODS A qualitative descriptive approach was taken. Recruitment was via a larger clinical feasibility study. Some women who consented to take part in the clinical feasibility study also consented to being interviewed during the postnatal period. Transcripts were thematically analysed. FINDINGS Women reported improved comfort when wearing the non-invasive fetal electrocardiogram device. They appreciated how it enabled freedom of movement and an ability to actively participate in labour. They compared their experience with previous use of cardiotocography which they felt compromised their bodily autonomy. All forms of continuous electronic fetal monitoring experienced by women resulted in the unwelcome experience of 'Poking and prodding' by the midwife. DISCUSSION Continuous electronic fetal monitoring can negatively impact women's labour and birth experience, particularly when the measurement of fetal wellbeing is prioritised. CONCLUSION The way in which continuous electronic fetal monitoring technology is designed and used is an important component of optimising physiological processes and positive experiences for women during labour and birth for women with complex pregnancies. Non-invasive fetal electrocardiograpy is a promising additional option for women.
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Affiliation(s)
- Rebecca Coddington
- Collaborative of Midwifery, Child and Family Health, University of Technology Sydney, Australia.
| | - Vanessa Scarf
- Collaborative of Midwifery, Child and Family Health, University of Technology Sydney, Australia
| | - Deborah Fox
- Collaborative of Midwifery, Child and Family Health, University of Technology Sydney, Australia
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Al-yousif S, Najm IA, Talab HS, Hasan Al Qahtani N, Alfiras M, Al-Rawi OYM, Subhi Al-Dayyeni W, Amer Ahmed Alrawi A, Jabbar Mnati M, Jarrar M, Ghabban F, Al-Shareefi NA, Musa Jaber M, H. Saleh A, Md Tahir N, Najim HT, Taher M. Intrapartum cardiotocography trace pattern pre-processing, features extraction and fetal health condition diagnoses based on RCOG guideline. PeerJ Comput Sci 2022; 8:e1050. [PMID: 36092005 PMCID: PMC9454876 DOI: 10.7717/peerj-cs.1050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 06/30/2022] [Indexed: 06/15/2023]
Abstract
CONTEXT The computerization of both fetal heart rate (FHR) and intelligent classification modeling of the cardiotocograph (CTG) is one of the approaches that are utilized in assisting obstetricians in conducting initial interpretation based on (CTG) analysis. CTG tracing interpretation is crucial for the monitoring of the fetal status during weeks into the pregnancy and childbirth. Most contemporary studies rely on computer-assisted fetal heart rate (FHR) feature extraction and CTG categorization to determine the best precise diagnosis for tracking fetal health during pregnancy. Furthermore, through the utilization of a computer-assisted fetal monitoring system, the FHR patterns can be precisely detected and categorized. OBJECTIVE The goal of this project is to create a reliable feature extraction algorithm for the FHR as well as a systematic and viable classifier for the CTG through the utilization of the MATLAB platform, all the while adhering to the recognized Royal College of Obstetricians and Gynecologists (RCOG) recommendations. METHOD The compiled CTG data from spiky artifacts were cleaned by a specifically created application and compensated for missing data using the guidelines provided by RCOG and the MATLAB toolbox after the implemented data has been processed and the FHR fundamental features have been extracted, for example, the baseline, acceleration, deceleration, and baseline variability. This is followed by the classification phase based on the MATLAB environment. Next, using the guideline provided by the RCOG, the signals patterns of CTG were classified into three categories specifically as normal, abnormal (suspicious), or pathological. Furthermore, to ensure the effectiveness of the created computerized procedure and confirm the robustness of the method, the visual interpretation performed by five obstetricians is compared with the results utilizing the computerized version for the 150 CTG signals. RESULTS The attained CTG signal categorization results revealed that there is variability, particularly a trivial dissimilarity of approximately (+/-4 and 6) beats per minute (b.p.m.). It was demonstrated that obstetricians' observations coincide with algorithms based on deceleration type and number, except for acceleration values that differ by up to (+/-4). DISCUSSION The results obtained based on CTG interpretation showed that the utilization of the computerized approach employed in infirmaries and home care services for pregnant women is indeed suitable. CONCLUSIONS The classification based on CTG that was used for the interpretation of the FHR attribute as discussed in this study is based on the RCOG guidelines. The system is evaluated and validated by experts based on their expert opinions and was compared with the CTG feature extraction and classification algorithms developed using MATLAB.
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Affiliation(s)
- Shahad Al-yousif
- Research Centre, The University of Almashreq, Baghdad, Iraq
- College of Engineering, Department of Electrical & Electronic Engineering, Gulf University, Almasnad, Kingdom of Bahrain
- Department of Medical Instrumentation Engineering Techniques, Dijlah University College, Baghdad, Iraq
| | - Ihab A. Najm
- College of Engineering, Tikrit University, Tikrit, Iraq
| | - Hossam Subhi Talab
- Children Welfare Teaching Hospital, Medical City, (MD, CABP, CAB Neonatology), Baghdad, Iraq
| | - Nourah Hasan Al Qahtani
- Department of Obstetrics and Gynecology, College of Medicine, Imam Abdulrahman Bin Faisal University, Al Dammam, Saudi Arabia
| | - M. Alfiras
- College of Engineering, Department of Electrical & Electronic Engineering, Gulf University, Almasnad, Kingdom of Bahrain
| | - Osama YM Al-Rawi
- College of Engineering, Department of Electrical & Electronic Engineering, Gulf University, Almasnad, Kingdom of Bahrain
| | | | | | - Mohannad Jabbar Mnati
- Department of Electronic Technology, Institute of Technology Baghdad, Middle Technical University, Baghdad, Iraq
| | - Mu’taman Jarrar
- College of Medicine, Imam Abdulrahman Bin Faisal University, Al Dammam, Saudi Arabia
| | - Fahad Ghabban
- Department of Information Systems College of Computer Science and Engineering, Taibah University, Al Madinah Al Munawwarah, Saudi Arabia
| | - Nael A. Al-Shareefi
- College of Biomedical Informatics, University of Information Technology and Communications (UOITC), Baghdad, Iraq
| | - Mustafa Musa Jaber
- Al-Turath University College, Department of Computer Engineering, Baghdad, Iraq
- Department of Medical Instruments Engineering Techniques, Al-Farahidi University, Baghdad, Iraq
| | | | - Nooritawati Md Tahir
- Electrical Engineering Department, College of Engineering, Universiti Teknologi MARA, Shah Alam, Malaysia
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Shah Alam, Malaysia
- Institute of Big Data Analytics and Artificial Intelligence (IBDAAI), Universiti Teknologi MARA, Shah Alam, Malaysia
| | - Huda T. Najim
- Department of Biomedical Engineering, University of Technology, Baghdad, Iraq
| | - Mayada Taher
- Department of Laser and Optoelectronics Engineering, University of Technology, Baghdad, Iraq
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Ghesquière L, Ternynck C, Sharma D, Hamoud Y, Vanspranghels R, Storme L, Houfflin-Debarge V, De Jonckheere J, Garabedian C. Heart rate markers for prediction of fetal acidosis in an experimental study on fetal sheep. Sci Rep 2022; 12:10615. [PMID: 35739219 PMCID: PMC9226053 DOI: 10.1038/s41598-022-14727-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 06/10/2022] [Indexed: 11/09/2022] Open
Abstract
To overcome the difficulties in interpreting fetal heart rate (FHR), several tools based on the autonomic nervous system and heart rate variability (HRV) have been developed. The objective of this study was to use FHR and HRV parameters for the prediction of fetal hypoxia. It was an experimental study in the instrumented fetal sheep. Repeated umbilical cord occlusions were performed to achieve severe acidosis. Hemodynamic parameters, ECG, and blood gases were analyzed. The variables used were heart rate baseline, HRV analysis (RMSSD, SDNN, LF, HF, HFnu, Fetal Stress Index (FSI), …), and morphological analysis of decelerations. The gold standard used to classify hypoxia was the fetal arterial pH (pH < 7.10). Different multivariable statistical methods (logistic regression and decision trees) were applied for the detection of acidosis. 21 lambs were instrumented. A total of 130 pairs of FHR/fetal pH analysis were obtained of which 29 in the acidosis group and 101 in the non-acidosis group. After logistic regression model with bootstrap resampling and stepwise backward selection, only one variable was selected, FSI. The AUC of FSI alone in this model was 0.81 with a sensitivity of 0.66, specificity of 0.88, PPV of 0.61, and NPV of 0.90 considering a threshold of 68. Decision trees with CHAID and CART algorithms showed a sensitivity of 0.48 and 0.59, respectively, and a specificity of 0.94 for both. All employed methods identified HRV variables as the most predictive of acidosis. The primary variables selected automatically were those from the HRV. Supporting the use of FHRV measures for the screening of fetal acidosis during labour is interesting.
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Affiliation(s)
- Louise Ghesquière
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France.
- Department of Obstetrics, CHU Lille, 59000, Lille, France.
- Department of Obstetrics, CHU Lille, Avenue Eugène Avinée, 59037, Lille Cedex, France.
| | - C Ternynck
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- Department of Biostatistics, CHU Lille, 59000, Lille, France
| | - D Sharma
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- Department of Pediatric Surgery, CHU Lille, 59000, Lille, France
| | - Y Hamoud
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- Department of Obstetrics, CHU Lille, 59000, Lille, France
| | - R Vanspranghels
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- Department of Obstetrics, CHU Lille, 59000, Lille, France
| | - L Storme
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- Department of Neonatology, CHU Lille, 59000, Lille, France
| | - V Houfflin-Debarge
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- Department of Obstetrics, CHU Lille, 59000, Lille, France
| | - J De Jonckheere
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- CHU Lille, CIC-IT 1403, 59000, Lille, France
| | - C Garabedian
- Univ. Lille, CHU Lille, ULR 2694-METRICS-Evaluation des technologies de santé et des pratiques médicales, 59000, Lille, France
- Department of Obstetrics, CHU Lille, 59000, Lille, France
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Cao Q, Ma C, Zhu J. Ultrasound Doppler fetal heart rate detection algorithm analyzes the correlation between twin selective fetal growth restriction and cord blood SFass fasL level. Pak J Med Sci 2021; 37:1672-1676. [PMID: 34712304 PMCID: PMC8520371 DOI: 10.12669/pjms.37.6-wit.4881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/12/2021] [Accepted: 07/08/2021] [Indexed: 11/15/2022] Open
Abstract
Objective The paper uses ultrasound Doppler fetal heart rate detection algorithm to explore the placental characteristics of monochorionic twin pregnancy with selective fetal growth restriction, and discuss the correlation between selective fetal growth restriction and cord blood SFass FasL level. Methods From June 1, 2019 to June 1, 2020 in our hospital, 23 cases of selective fetal growth restriction and 32 cases of uncomplicated cases were included in the monochorionic twin pregnancies whose pregnancy was terminated in our hospital (control group) research. Perfusion was completed within 24 hours after delivery of the placenta. The umbilical arteries and veins of the two fetuses were respectively perfused with four different colors of pigments. The type of anastomoses was judged according to the color of the blood vessels on the placenta surface. Results The selective fetal growth restriction group was higher than the control group. In the selective fetal growth restriction group and the control group, the number of anastomoses of the placental superficial arterial artery, arterial vein and venous vein were 1.0 and 1.0, 3.0 and 2.0, 0.0 and 0.0, respectively; the placental superficial arterial artery, arterial vein and venous vein. The total diameters of the anastomosed blood vessels were 2.7 and 2.2, 4.0 and 3.4, 0.0 and 0.0 mm, respectively; the total number of superficial placental anastomosed blood vessels in the selective fetal growth restriction group and the control group were 3.5 and 3.5, respectively.The total diameters were 6.9 and 6.9, respectively 5.9mm. Conclusion Uneven placental share and non-central attachment of the umbilical cord may be risk factors for selective fetal growth restriction in monochorionic twin pregnancy.
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Affiliation(s)
- Qiaohong Cao
- Qiaohong Cao, Bachelor's Degrees. Department of Obstetrics and Gynecology, Wenling Maternal and Child Health Care Hospital, Wenling, 317500, Zhejiang, China
| | - Cong Ma
- Cong Ma, Bachelor's Degrees. Department of Obstetrics and Gynecology, Wenling Maternal and Child Health Care Hospital, Wenling, 317500, Zhejiang, China
| | - Junbiao Zhu
- Junbiao Zhu, Bachelor's Degrees. Department of Obstetrics and Gynecology, Wenling Maternal and Child Health Care Hospital, Wenling, 317500, Zhejiang, China
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Kapaya H, Jacques R, Almond T, Rosser MH, Anumba D. Is short-term-variation of fetal-heart-rate a better predictor of fetal acidaemia in labour? A feasibility study. PLoS One 2020; 15:e0236982. [PMID: 32745099 PMCID: PMC7398510 DOI: 10.1371/journal.pone.0236982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 07/18/2020] [Indexed: 11/22/2022] Open
Abstract
Background Continuous intrapartum fetal monitoring is challenging and its clinical benefits are debated. The project evaluated whether short-term-variation (STV) and other computerised fetal heart rate (FHR) parameters (baseline FHR, long-term-variation, accelerations and decelerations) predicted acidaemia at birth. The aims of the study were to assess the changes in FHR pattern during labour and determine the feasibility of undertaking a definitive trial by reporting the practicalities of using the monitoring device, participant recruitment, data collection and staff training. Methods 200 high-risk women carrying a term singleton, non-anomalous fetus, requiring continuous FHR monitoring in labour were consented to participate from the Jessop Wing maternity unit, Sheffield, UK. The trans-abdominal fetal ECG monitor was placed as per clinical protocol. During the monitoring session, clinicians were blinded to the computerised FHR parameters. We analysed the last hour of the FHR and its ability to predict umbilical arterial blood pH <7.20 using receiver operator characteristics (ROC) curves. Results Of 200 women, 137 cases were excluded as either the monitor did not work from the onset of labour (n = 30), clinical staff did not return or used the monitor on another patient (n = 37), umbilical cord blood not obtained (n = 25), FHR data not recorded within an hour of birth (n = 34) and other reasons (n = 11). In 63 cases included in the final analysis, the computer-derived FHR parameters did not show significant correlation with umbilical artery cord pH <7.20. Labour was associated with a significant increase in short and long term variation of FHR and number of deceleration (P<0.001). However, baseline FHR decreased significantly before delivery (P<0.001). Conclusions The project encountered a number of challenges, with learning points crucial to informing the design of a large study to evaluate the potential place of intrapartum computerised FHR parameters, using abdominal fetal ECG monitor before its clinical utility and more widespread adoption can be ascertained.
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Affiliation(s)
- Habiba Kapaya
- Sheffield Teaching Hospitals, NHS Foundation Trust, Tree Root Walk, Sheffield, United Kingdom
- * E-mail:
| | - Richard Jacques
- Medical Statistics Group, School of Health and Related Research (ScHARR), University of Sheffield, United Kingdom
| | - Thomas Almond
- Obstetrics and Gynaecology, Sheffield Teaching Hospitals, NHS Foundation Trust, Tree Root Walk, Sheffield, United Kingdom
| | - Miss Hilary Rosser
- Obstetrics and Gynaecology, Sheffield Teaching Hospitals, NHS Foundation Trust, Tree Root Walk, Sheffield, United Kingdom
| | - Dilly Anumba
- Academic Unit of Reproductive and Developmental Medicine, University of Sheffield, Tree Root Walk, Sheffield, United Kingdom
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