Imperial College London

Dr Lin Foo

Faculty of MedicineDepartment of Metabolism, Digestion and Reproduction

Honorary Clinical Research Fellow
 
 
 
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f.foo

 
 
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Commonwealth BuildingHammersmith Campus

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Summary

 

Publications

Publication Type
Year
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22 results found

Masini G, Foo LF, Tay J, Wilkinson IB, Valensise H, Gyselaers W, Lees CCet al., 2021, Preeclampsia has 2 phenotypes which require different treatment strategies, American Journal of Obstetrics and Gynecology, ISSN: 0002-9378

Journal article

Foo L, Johnson S, Marriott L, Bourne T, Bennett P, Lees Cet al., 2020, Peri-implantation urinary hormone monitoring distinguishes between types of first-trimester spontaneous pregnancy loss, Paediatric and Perinatal Epidemiology, Vol: 34, Pages: 495-503, ISSN: 0269-5022

BackgroundLutenising hormone (LH) and human chorionic gonadotropin (hCG) hormone are useful biochemical markers to indicate ovulation and embryonic implantation, respectively. We explored “point‐of‐care” LH and hCG testing using a digital home‐testing device in a cohort trying to conceive.ObjectiveTo determine conception and spontaneous pregnancy loss rates, and to assess whether trends in LH‐hCG interval which are known to be associated with pregnancy viability could be identified with point‐of‐care testing.MethodsWe recruited healthy women aged 18‐44 planning a pregnancy. Participants used a home monitor to track LH and hCG levels for 12 menstrual cycles or until pregnancy was conceived. Pregnancy outcomes (viable, clinical miscarriage, or biochemical pregnancy loss) were recorded. Monitor data were analysed by a statistician blinded to pregnancy outcome.ResultsFrom 387 recruits, there were 290 pregnancies with known outcomes within study timeline. Adequate monitor data for analysis were available for 150 conceptive cycles. Overall spontaneous first‐trimester pregnancy loss rate was 30% with clinically recognised miscarriage rate of 17%. The difference to LH‐hCG interval median had wider spread for biochemical losses (0.5‐8.5 days) compared with clinical miscarriage (0‐5 days) and viable pregnancies (0‐6 days). Fixed effect hCG profile change distinguished between pregnancy outcomes from as early as day‐2 post‐hCG rise from baseline.ConclusionThe risk of first‐trimester spontaneous pregnancy loss in our prospective cohort is comparable to studies utilising daily urinary hCG collection and laboratory assays. A wider LH‐hCG interval range is associated with biochemical pregnancy loss and may relate to late or early implantation. Although early hCG changes discriminate between pregnancies that will miscarry from viable pregnancies, this point‐of‐care testing model is not sufficiently developed to be predictive.

Journal article

Bijl RC, Valensise H, Novelli GP, Vasapollo B, Wilkinson I, Thilaganathan B, Stöhr EJ, Lees C, van der Marel CD, Cornette JMJ, International Working Group on Maternal Hemodynamicset al., 2019, Methods and considerations concerning cardiac output measurement in pregnant women: recommendations of the International Working Group on Maternal Hemodynamics, Ultrasound in Obstetrics and Gynecology, Vol: 54, Pages: 35-50, ISSN: 0960-7692

Cardiac output (CO), along with blood pressure and vascular resistance, is one of the most important parameters of maternal hemodynamic function. Substantial changes in CO occur in normal pregnancy and in most obstetric complications. With the development of several non‐invasive techniques for the measurement of CO, there is a growing interest in the determination of this parameter in pregnancy. These techniques were initially developed for use in critical‐care settings and were subsequently adopted in obstetrics, often without appropriate validation for use in pregnancy. In this article, methods and devices for the measurement of CO are described and compared, and recommendations are formulated for their use in pregnancy, with the aim of standardizing the assessment of CO and peripheral vascular resistance in clinical practice and research studies on maternal hemodynamics.

Journal article

Masini G, Foo LF, Cornette J, Tay J, Rizopoulos D, McEniery CM, Wilkinson IB, Lees CCet al., 2019, Cardiac output changes from prior to pregnancy to post partum using two non-invasive techniques, Heart, Vol: 105, Pages: 715-720, ISSN: 1355-6037

OBJECTIVES: We aimed to describe cardiac output (CO) trend from prepregnancy to post partum using an inert gas rebreathing (IGR) device and compare these measurements with those obtained by a pulse waveform analysis (PWA) technique, both cross-sectionally and longitudinally. METHODS: Non-smoking healthy women, aged 18-44 years, with body mass index <35 were included in this prospective observational study. CO measurements were collected at different time points (prepregnancy, at four different gestational epochs and post partum) using IGR and PWA. A linear mixed model analysis tested whether the longitudinal change in CO differed between the techniques. Bland-Altman analysis and intraclass correlation coefficient (ICC) were used for cross-sectional and a four-quadrant plot for longitudinal comparisons. RESULTS: Of the 413 participants, 69 had a complete longitudinal assessment throughout pregnancy. In this latter cohort, the maximum CO rise was seen at 15.2 weeks with IGR (+17.5% from prepregnancy) and at 10.4 weeks with PWA (+7.7% from prepregnancy). Trends differed significantly (p=0.0093). Cross-sectional analysis was performed in the whole population of 413 women: the mean CO was 6.14 L/min and 6.38 L/min for PWA and IGR, respectively, the percentage of error was 46% and the ICC was 0.348, with similar results at all separate time points. Longitudinal concordance was 64%. CONCLUSIONS: Despite differences between devices, the maximum CO rise in healthy pregnancies is more modest and earlier than previously reported. The two methods of CO measurement do not agree closely and cannot be used interchangeably. Technique-specific reference ranges are needed before they can be applied in research and clinical settings.

Journal article

Gyselaers W, Spaanderman M, International Working Group on Maternal Hemodynamics, 2018, Assessment of venous hemodynamics and volume homeostasis during pregnancy: recommendations of the International Working Group on Maternal Hemodynamics, Ultrasound in Obstetrics and Gynecology, Vol: 52, Pages: 174-185, ISSN: 0960-7692

Venous hemodynamics and volume homeostasis are important aspects of cardiovascular physiology. However, today their relevance is still very much underappreciated. Their most important role is maintenance and control of venous return and, as such, cardiac output. A high-flow/low-resistance circulation, remaining constant under physiological circumstances, is mandatory for an uncomplicated course of pregnancy. In this article, characteristics of normal and abnormal venous and volume regulating functions are discussed with respect to normal and pathologic outcomes of pregnancy, and current (non-invasive) methods to assess these functions are summarized. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Journal article

Foo F, Mahendru A, Masini G, Fraser A, Cacciatore S, MacIntyre DA, McEniery C, Wilkinson I, Bennett P, Lees Cet al., 2018, Association between prepregnancy cardiovascular function and subsequent preeclampsia or fetal growth restriction, Hypertension, Vol: 72, Pages: 442-450, ISSN: 0194-911X

Preeclampsia and fetal growth restriction during pregnancy are associated with increased risk of maternal cardiovascular disease later in life. It is unclear whether this association is causal or driven by similar antecedent risk factors. Clarification requires recruitment before conception which is methodologically difficult with high attrition rates and loss of outcome numbers to nonconception/miscarriage. Few prospective studies have, therefore, been adequately powered to address these questions. We recruited 530 healthy women (mean age: 35.0 years) intending to conceive and assessed cardiac output, cardiac index, stroke volume, total peripheral resistance, mean arterial pressure, and heart rate before pregnancy. Participants were followed to completion of subsequent pregnancy with repeat longitudinal assessments. Of 356 spontaneously conceived pregnancies, 15 (4.2%) were affected by preeclampsia and fetal growth restriction. Women who subsequently developed preeclampsia/fetal growth restriction had lower preconception cardiac output (4.9 versus 5.8 L/min; P=0.002) and cardiac index (2.9 versus 3.3 L/min per meter2; P=0.031) while mean arterial pressure (87.1 versus 82.3 mm Hg; P=0.05) and total peripheral resistance (1396.4 versus 1156.1 dynes sec cm−5; P<0.001) were higher. Longitudinal trajectories for cardiac output and total peripheral resistance were similar between affected and healthy pregnancies, but the former group showed a more exaggerated fall in mean arterial pressure in the first trimester, followed by a steeper rise and a steeper fall to postpartum values. Significant relationships were observed between cardiac output, total peripheral resistance, and mean arterial pressure and gestational epoch. We conclude that in healthy women, an altered prepregnancy hemodynamic phenotype is associated with the subsequent development of preeclampsia/fetal growth restriction.

Journal article

Tay J, Foo L, Masini G, Bennett PR, Mceniery CM, Wilkinson IB, Lees CCet al., 2018, Cardiac output in pre eclampsia is associated with the presence of fetal growth restriction, not gestation at onset: a prospective cohort study, American Journal of Obstetrics and Gynecology, Vol: 218, Pages: 517.e1-517.e12, ISSN: 0002-9378

BACKGROUND AND OBJECTIVES: Pre-eclampsia (PE) and fetal growth restriction (FGR) are considered to be placentally-mediated disorders. The clinical manifestations are widely held to relate to gestation age at onset with early- and late-onset PE considered to be phenotypically distinct. Recent studies have reported conflicting findings in relation to cardiovascular function, and in particular cardiac output, in PE and FGR. STUDY DESIGN: We investigated maternal cardiovascular function in relation to clinical subtype in 45 pathological pregnancies (14 'PE only', 16 'FGR only', 15 'PE and FGR') and compared these with 107 healthy person observations. Cardiac output (CO) was the primary outcome measure, and was assessed using an inert gas rebreathing method (Innocor®), from which peripheral vascular resistance was derived (PVR); arterial function was assessed by Vicorder ®, a cuff-based oscillometric device. Cardiovascular parameters were normalised for gestational age in relation to healthy pregnancies using Z scores, thus allowing for comparison across the gestational range 24-40 weeks. RESULTS: Compared with healthy control pregnancies, women with PE had higher CO Z scores (1.87 ± 1.35; p=0.0001) and lower PVR Z scores (-0.76± 0.89; p=0.025); those with FGR had higher PVR Z scores (0.57± 1.18; p=0.04) and those with both PE and FGR had lower CO Z scores (-0.80 ± 1.3; p= 0.007) and higher PVR Z scores (2.16 ± 1.96; p=0.0001). These changes were not related to gestational age of onset. All those affected by PE and/or FGR had abnormally raised augmentation index (AIx) and pulse wave velocity (PWV). Furthermore, in PE, low CO was associated with low birthweight and high CO with high birthweight. (r=0.42, p=0.03). CONCLUSIONS: PE is associated with high CO, but if PE presents with FGR, the opposite is true; both conditions are, nevertheless, defined by hypertension. FGR without PE is associated with high PVR. Though 'early' and 'l

Journal article

Foo L, Mahendry A, McEniery C, Wilkinson I, Bennett P, Lees Cet al., 2018, Pre-conception maternal haemodynamics is associated with subsequent development of pre-eclampsia (PE) or fetal growth restriction (FGR), Publisher: WILEY, Pages: 12-12, ISSN: 1470-0328

Conference paper

Meah VL, Backx K, Davenport MH, Bruckmann A, Cockcroft J, Cornette J, Duvekot JJ, Ferrazzi E, Foo FL, Ghossein-Doha C, Gyselaers W, Khalil A, McEniery CM, Lees C, Meah V, Novelli GP, Spaanderman M, Stohr E, Tay J, Thilaganathan B, Valensise H, Wilkinson Iet al., 2018, Functional hemodynamic testing in pregnancy: recommendations of the International Working Group on Maternal Hemodynamics, Ultrasound in Obstetrics and Gynecology, Vol: 51, Pages: 331-340, ISSN: 0960-7692

In the general population, functional hemodynamic testing, such as that during submaximal aerobic exercise and isometric handgrip, and the cold pressor test, has long been utilized to unmask abnormalities in cardiovascular function. During pregnancy, functional hemodynamic testing places additional demands on an already stressed maternal cardiovascular system. Dysfunctional responses to such tests in early pregnancy may predict the development of hypertensive disorders that develop later in gestation. For each of the above functional hemodynamic tests, these recommendations provide a description of the test, test protocol and equipment required, and an overview of the current understanding of clinical application during pregnancy.

Journal article

Foo FL, Masini G, Mceniery C, Wilkinson I, Bennett P, Lees Cet al., 2017, OC07.01 Pre-conception maternal haemodynamics is associated with subsequent development of pre-eclampsia (PE) or fetal growth restriction (FGR), ISUOG World Congress 2017, Publisher: Wiley, Pages: 12-13, ISSN: 0960-7692

Conference paper

Foo FL, McEniery CM, Lees C, Khalil A, International Working Group on Maternal Haemodynamicset al., 2017, Assessment of arterial function in pregnancy: recommendations of the International Working Group on Maternal Haemodynamics., Ultrasound in Obstetrics and Gynecology, Vol: 50, Pages: 324-331, ISSN: 0960-7692

There is strong evidence supporting the role of maternal arterial dysfunction in pregnancy-specific disorders such as pre-eclampsia and intrauterine growth restriction. As more work is focused towards this field, it is important that methods and interpretation of arterial function assessment are applied appropriately. Here, we summarize techniques and devices commonly used in maternal health studies, with consideration of their technical application in pregnant cohorts.

Journal article

Usman S, Foo L, Tay J, Bennett PR, Lees Cet al., 2017, Authors' reply [Use of magnesium sulfate in preterm deliveries for neuroprotection of the neonate], Obstetrician and Gynaecologist, Vol: 19, Pages: 255-256, ISSN: 1744-4667

Journal article

Foo FL, Collins A, McEniery CM, Bennett PR, Wilkinson IB, Lees CCet al., 2017, Preconception and early pregnancy maternal haemodynamic changes in healthy women in relation to pregnancy viability, Human Reproduction, Vol: 32, Pages: 985-992, ISSN: 1460-2350

STUDY QUESTIONAre there differences in preconception cardiovascular function between women who have a viable pregnancy and those who have a first trimester miscarriage?SUMMARY ANSWERPreconception cardiovascular function of central haemodynamics and arterial function are similar between women who have a viable pregnancy and those who have a first trimester miscarriage.WHAT IS KNOWN ALREADYMiscarriages have been associated with increased long-term cardiovascular disease risk, and arterial and cardiovascular dysfunction has been hypothesised as the common link. It is not known if these risks are present prior to pregnancy or are a reflection of poor arterial and haemodynamic adaptation to pregnancy.STUDY DESIGN, SIZE, DURATIONThis prospective longitudinal preconception cohort study was conducted over 18 months. In total, 367 participants were recruited pre-pregnancy, from which 197 pregnancies were recorded; 39 of these pregnancies ended in first trimester miscarriage. Complete longitudinal data were available for 172 pregnancies (140 viable pregnancies, 32 first trimester miscarriages) from pre-pregnancy to 6 weeks gestation.PARTICIPANTS/MATERIALS, SETTING, METHODSThis was a single site study based at a maternity hospital in London. Healthy women were recruited prior to natural conception and followed up once they became pregnant. All underwent haemodynamic [cardiac output (CO), peripheral vascular resistance (PVR)] and arterial function [aortic augmentation index (AIx) and pulse wave velocity (PWV)] testing prior to pregnancy and at 6 weeks gestation, using non-invasive devices (gas re-breathing method, Innocor® and an occilometric device, Vicorder®). Cross-sectional measurements at pre-pregnancy and 6 weeks gestation and a longitudinal analysis of changes were compared between women who had a subsequent viable pregnancy, and those who had a subsequent first trimester miscarriage.MAIN RESULTS AND THE ROLE OF CHANCEThere were no differences between women desti

Journal article

Mahendru AA, Foo FL, McEniery CM, Everett TR, Wilkinson IB, Lees CCet al., 2017, Change in maternal cardiac output from pre-conception to mid-pregnancy is associated with birth weight in healthy pregnancies, Ultrasound in Obstetrics & Gynecology, Vol: 49, Pages: 78-84, ISSN: 1469-0705

OBJECTIVE: Birth weight (BW) is thought to be determined by maternal health, and genetic, nutritional and placental factors; the latter being influenced by anatomical development and perfusion. Maternal cardiovascular changes contribute to uteroplacental perfusion, however they have not been investigated in relation to fetal growth/BW. Our aim was to explore the relationship between maternal cardiovascular adaptation, fetal growth and BW in healthy pregnancies. METHODS: This was a longitudinal prospective study of women planning to conceive a pregnancy. Maternal cardiac output (CO), cardiac index (CI), pulse-wave velocity, aortic augmentation index (AIx), central blood pressure and peripheral vascular resistance (PVR) were assessed prior to pregnancy and at 6, 23 and 33 weeks' gestation. Fetal growth was assessed by serial ultrasound measurements of biometry. RESULTS: In total, 143 women volunteered to participate and were eligible for study inclusion. One hundred and one women conceived within 18 months and there were 64 live births with normal pregnancy outcome. There were positive correlations between BW and the prepregnancy-to-second trimester changes in CO (ρ = 0.4, P = 0.004), CI (ρ = 0.3, P = 0.02) and PVR (ρ = 0.3, P = 0.02). There were significant associations between third-trimester estimated fetal weight gain and the prepregnancy-to-second trimester increase in CO (Δ, 0.8 ± 1.2 L/min; ρ = 0.3, P = 0.02) and CI (Δ, 0.4 ± 0.6 L/min/m(2) ; ρ = 0.3, P = 0.04) and reduction in AIx (Δ, -10 ± 9%; ρ = -0.3, P = 0.04). CONCLUSIONS: In healthy pregnancy, third-trimester fetal growth and BW are associated with incremental changes in maternal CO in early pregnancy. It is plausible that this association is causative, as changes predate third-trimester fetal growth and eventual BW.

Journal article

Usman S, Foo L, Tay J, Bennett PR, Lees Cet al., 2017, Use of magnesium sulfate in preterm deliveries for neuroprotection of the neonate, Obstetrician and Gynaecologist, Vol: 19, Pages: 21-28, ISSN: 1744-4667

Key content The prevalence of preterm birth is increasing and owing to advances in neonatal care, more infants are surviving. However, in parallel with this, the incidence of cerebral palsy (CP) is also rising. Magnesium sulfate (MgSO4) is currently recommended for use in women who are at risk of giving birth at less than 30–32 weeks of gestation for neuroprotection of their infants. The exact mechanism of action remains unclear. Meta‐analyses report encouraging results that are consistent with a modest but tangible benefit for the use of MgSO4, and suggest a number needed to treat (NNT) to prevent one in 46 cases of CP in infants born preterm before 30 weeks of gestation and one in 63 cases of CP in infants born preterm before 34 weeks of gestation.Learning objectives To gain an understanding of the risk of neurodisability in infants delivered preterm. To become familiar with the main studies assessing the use of MgSO4 for neuroprotection in preterm deliveries. To become aware of the relevant international guidelines.Ethical issues Concerns have been raised regarding the higher number of perinatal deaths reported with the use of MgSO4 in the MagNET study. This was not substantiated in the Cochrane review. Given that MgSO4 is a safe, readily available and inexpensive drug, even if there were only to be modest benefits from its use, the risk–benefit ratio is in favour of its use.

Journal article

Foo L, Gautreau A, Bennett P, Lees Cet al., 2016, Gestation of pregnancy loss in an observational prospective preconception cohort, British Maternal & Fetal Medicine Society (BMFMS) 18th Annual Conference 2016, Publisher: WILEY-BLACKWELL, Pages: 58-58, ISSN: 1470-0328

Conference paper

Finer S, Mathews C, Lowe R, Smart M, Hillman S, Foo L, Sinha A, Williams D, Rakyan VK, Hitman GAet al., 2015, Maternal gestational diabetes is associated with genome-wide DNA methylation variation in placenta and cord blood of exposed offspring., Hum Mol Genet, Vol: 24, Pages: 3021-3029

Exposure of a developing foetus to maternal gestational diabetes (GDM) has been shown to programme future risk of diabetes and obesity. Epigenetic variation in foetal tissue may have a mechanistic role in metabolic disease programming through interaction of the pregnancy environment with gene function. We aimed to identify genome-wide DNA methylation variation in cord blood and placenta from offspring born to mothers with and without GDM. Pregnant women of South Asian origin were studied and foetal tissues sampled at term delivery. The Illumina HumanMethylation450 BeadChip was used to assay genome-wide DNA methylation in placenta and cord blood from 27 GDM exposed and 21 unexposed offspring. We identified 1485 cord blood and 1708 placenta methylation variable positions (MVPs) achieving genome-wide significance (adjusted P-value <0.05) with methylation differences of >5%. MVPs were disproportionately located within first exons. A bioinformatic co-methylation algorithm was used to detect consistent directionality of methylation in 1000 bp window around each MVP was observed at 74% of placenta and 59% of cord blood MVPs. KEGG pathway analysis showed enrichment of pathways involved in endocytosis, MAPK signalling and extracellular triggers to intracellular metabolic processes. Replication studies should integrate genomics and transcriptomics with longitudinal sampling to elucidate stability, determine causality for translation into biomarker and prevention studies.

Journal article

Foo L, Tay J, Lees CC, McEniery CM, Wilkinson IBet al., 2015, Hypertension in Pregnancy: Natural History and Treatment Options, CURRENT HYPERTENSION REPORTS, Vol: 17, ISSN: 1522-6417

Journal article

Foo L, Bewley S, Rudd A, 2013, Maternal death from stroke: a thirty year national retrospective review, European Journal of Obstetrics & Gynecology and Reproductive Biology, Vol: 171, Pages: 266-270, ISSN: 0301-2115

Journal article

Foo F, 2011, Birth Rites and Rights, Birth Rites and Rights, Editors: Ebtehaj, Herring, Johnson, Richards, Publisher: Bloomsbury Publishing, ISBN: 9781847318572

What is the significance of changes of the age at which women give birth? This stimulating collection of papers provides new insights into one of life&#39;s most momentous moments.

Book chapter

Foo F, 2011, Birth Rites and Rights, Birth Rites and Rights, Editors: Ebtehaj, Herring, Johnson, Richards, Publisher: Bloomsbury Publishing, ISBN: 9781847318572

What is the significance of changes of the age at which women give birth? This stimulating collection of papers provides new insights into one of life&#39;s most momentous moments.

Book chapter

Bewley S, Foo L, Braude P, 2011, Adverse outcomes from IVF, BMJ, Vol: 342, Pages: d436-d436, ISSN: 0959-8138

Journal article

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