Assessment of the association between ambient air pollution and stillbirth in the UK: Results from a secondary analysis of the MiNESS case-control study

OBJECTIVE

We examined whether the risk of stillbirth was related to ambient air pollution in a UK population.

DESIGN

Prospective case-control study.

SETTING

Forty-one maternity units in the UK.

POPULATION

Women who had a stillbirth ≥28 weeks' gestation (n = 238) and women with an ongoing pregnancy at the time of interview (n = 597).

METHODS

Secondary analysis of data from the Midlands and North of England Stillbirth case-control study only including participants domiciled within 20 km of fixed air pollution monitoring stations. Pollution exposure was calculated using pollution climate modelling data for NO2 , NOx and PM2.5 . The association between air pollution exposure and stillbirth risk was assessed using multivariable logistic regression adjusting for household income, maternal body mass index (BMI), maternal smoking, Index of Multiple Deprivation quintile and household smoking and parity.

MAIN OUTCOME MEASURE

Stillbirth.

RESULTS

There was no association with whole pregnancy ambient air pollution exposure and stillbirth risk, but there was an association with preconceptual NO2 exposure (adjusted odds ratio [aOR] 1.06, 95% CI 1.01-1.08 per microg/m3 ). Risk of stillbirth was associated with maternal smoking (aOR 2.54, 95% CI 1.38-4.71), nulliparity (aOR 2.16, 95% CI 1.55-3.00), maternal BMI (aOR 1.05, 95% CI 1.01-1.08) and placental abnormalities (aOR 4.07, 95% CI 2.57-6.43).

CONCLUSIONS

Levels of ambient air pollution exposure during pregnancy in the UK, all of were beneath recommended thresholds, are not associated with an increased risk of stillbirth. Periconceptual exposure to NO2 may be associated with increased risk but further work is required to investigate this association.

CHronic hypERtension and L-citRulline studY (CHERRY): an Early-Phase Randomised Controlled Trial in Pregnancy

Oral supplementation with L-citrulline, which is sequentially converted to L-arginine then nitric oxide, improves vascular biomarkers and reduces blood pressure in non-pregnant, hypertensive human cohorts and pregnant mice with a pre-eclampsia-like syndrome. This early-phase randomised feasibility trial assessed the acceptability of L-citrulline supplementation to pregnant women with chronic hypertension and its effects on maternal BP and other vascular outcomes. Pregnant women with chronic hypertension were randomised at 12-16 weeks to receive 3-g L-citrulline twice daily (n = 24) or placebo (n = 12) for 8 weeks. Pregnant women reported high acceptability of oral L-citrulline. Treatment increased maternal plasma levels of citrulline, arginine and the arginine:asymmetric dimethylarginine ratio, particularly in women reporting good compliance. L-citrulline had no effect on diastolic BP (L-citrulline: - 1.82 95% CI (- 5.86, 2.22) vs placebo: - 5.00 95% CI (- 12.76, 2.76)), uterine artery Doppler or angiogenic biomarkers. Although there was no effect on BP, retrospectively, this study was underpowered to detect BP changes < 9 mmHg, limiting the conclusions about biological effects. The increase in arginine:asymmetric dimethylarginine ratio was less than in non-pregnant populations, which likely reflects altered pharmacokinetics of pregnancy, and further pharmacokinetic assessment of L-citrulline in pregnancy is advised.Trial Registration EudraCT 2015-005792-25 (2017-12-22) and ISRCTN12695929 (2018-09-20).

Fetoplacental vascular effects of maternal adrenergic antihypertensive and cardioprotective medications in pregnancy

Maternal cardiovascular diseases, including hypertension and cardiac conditions, are associated with poor fetal outcomes. A range of adrenergic antihypertensive and cardioprotective medications are often prescribed to pregnant women to reduce major maternal complications during pregnancy. Although these treatments are not considered teratogenic, they may have detrimental effects on fetal growth and development, as they cross the fetoplacental barrier, and may contribute to placental vascular dysregulation. Medication risk assessment sheets do not include specific advice to clinicians and women regarding the safety of these therapies for use in pregnancy and the potential off-target effects of adrenergic medications on fetal growth have not been rigorously conducted. Little is known of their effects on the fetoplacental vasculature. There is also a dearth of knowledge on adrenergic receptor activation and signalling within the endothelium and vascular smooth muscle cells of the human placenta, a vital organ in the maintenance of adequate blood flow to satisfy fetal growth and development. The fetoplacental circulation, absent of sympathetic innervation, and unique in its reliance on endocrine, paracrine and autocrine influence in the regulation of vascular tone, appears vulnerable to dysregulation by adrenergic antihypertensive and cardioprotective medications compared with the adult peripheral circulation. This semi-systematic review focuses on fetoplacental vascular expression of adrenergic receptors, associated cell signalling mechanisms and predictive consequences of receptor activation/deactivation by antihypertensive and cardioprotective medications.

Prevalence of pre-eclampsia and adverse pregnancy outcomes in women with pre-existing cardiomyopathy: a multi-centre retrospective cohort study

Pre-eclampsia is associated with postnatal cardiac dysfunction; however, the nature of this relationship remains uncertain. This multicentre retrospective cohort study aimed to determine the prevalence of pre-eclampsia in women with pre-existing cardiac dysfunction (left ventricular ejection fraction < 55%) and explore the relationship between pregnancy outcome and pre-pregnancy cardiac phenotype. In this cohort of 282 pregnancies, pre-eclampsia prevalence was not significantly increased (4.6% [95% C.I 2.2-7.0%] vs. population prevalence of 4.6% [95% C.I. 2.7-8.2], p = 0.99); 12/13 women had concurrent obstetric/medical risk factors for pre-eclampsia. The prevalence of preterm pre-eclampsia (< 37 weeks) and fetal growth restriction (FGR) was increased (1.8% vs. 0.7%, p = 0.03; 15.2% vs. 5.5%, p < 0.001, respectively). Neither systolic nor diastolic function correlated with pregnancy outcome. Antenatal ß blockers (n = 116) were associated with lower birthweight Z score (adjusted difference - 0.31 [95% C.I. - 0.61 to - 0.01], p = 0.04). To conclude, this study demonstrated a modest increase in preterm pre-eclampsia and significant increase in FGR in women with pre-existing cardiac dysfunction. Our results do not necessarily support a causal relationship between cardiac dysfunction and pre-eclampsia, especially given the population's background risk status. The mechanism underpinning the relationship between cardiac dysfunction and FGR merits further research but could be influenced by concomitant ß blocker use.

Plasma S1P and Sphingosine are not Different Prior to Pre-Eclampsia in Women at High Risk of Developing the Disease

Sphingolipids like sphingosine-1-phosphate (S1P) have been implicated in the pathophysiology of pre-eclampsia. We hypothesized that plasma S1P would be increased in women at high risk of developing pre-eclampsia who subsequently develop the disease. Low circulating placental growth factor (PlGF) is known to be associated with development of pre-eclampsia; so further, we hypothesized that increased S1P would be associated with concurrently low PlGF. This was a case-control study using stored maternal blood samples from 14 to 24 weeks of pregnancy, collected from 95 women at increased risk of pre-eclampsia. Pregnancy outcome was classified as uncomplicated, preterm pre-eclampsia (<37 weeks), or term pre-eclampsia. Plasma lipids were extracted and analyzed by ultraperformance liquid chromatography coupled to electrospray ionization MS/MS to determine concentrations of S1P and sphingosine. Median plasma S1P was 0.339 nmol/ml, and median sphingosine was 6.77 nmol/l. There were no differences in the plasma concentrations of S1P or sphingosine in women who subsequently developed pre-eclampsia, no effect of gestational age, fetal sex, ethnicity, or the presence of pre-existing hypertension. There was a correlation between S1P and sphingosine plasma concentration (P < 0.0001). There was no relationship between S1P or sphingosine with PlGF. Previous studies have suggested that plasma S1P may be a biomarker of pre-eclampsia. In our larger study, we failed to demonstrate there are women at high risk of developing the disease. We did not show a relationship with known biomarkers of the disease, suggesting that S1P is unlikely to be a useful predictor of the development of pre-eclampsia later in pregnancy.

Postnatal cardiovascular morbidity following preterm pre-eclampsia: An observational study

OBJECTIVE

To explore the nature of postnatal cardiovascular morbidity following pregnancies complicated by preterm pre-eclampsia and investigate associations between pregnancy characteristics and maternal postnatal cardiovascular function.

STUDY DESIGN

This was an observational sub-study of a single-centre feasibility randomised double-blind placebo-controlled trial (https://www.

CLINICALTRIALS

gov; NCT03466333), involving women with preterm pre-eclampsia, delivering before 37 weeks. Eligible women underwent echocardiography, arteriography and blood pressure monitoring within three days of birth, six weeks and six months postpartum. Correlations between pregnancy and cardiovascular characteristics were assessed using Spearman's correlation.

MAIN OUTCOME MEASURES

The prevalence of cardiovascular dysfunction and remodelling six months following preterm pre-eclampsia.

RESULTS

Forty-four women completed the study. At six months, 27 (61 %) had diastolic dysfunction, 33 (75 %) had raised total vascular resistance (TVR) and 18 (41 %) had left ventricular remodelling. Sixteen (46 %) women had de novo hypertension by six months and only two (5 %) women had a completely normal echocardiogram. Echocardiography did not change significantly from six weeks to six months. Earlier gestation at delivery and lower birthweight centile were associated with worse six-month diastolic dysfunction (E/E': rho = -0.39, p = 0.001 & rho = -0.42, p = 0.005) and TVR (rho = -0.34, p = 0.02 & rho = -0.37, p = 0.01).

CONCLUSIONS

Preterm pre-eclampsia is associated with persistent cardiovascular morbidity-six months postpartum in the majority of women. These cardiovascular changes have significant implications for long-term cardiovascular health. The graded severity of diastolic dysfunction and TVR with worsening pre-eclampsia phenotype suggests a dose-effect. However, the mechanistic link remains uncertain.

Noninvasive prenatal screening in twin pregnancies with cell-free DNA using the IONA test: a prospective multicenter study

BACKGROUND

In singleton pregnancies, studies investigating cell-free DNA in maternal blood have consistently reported high detection rate and low false-positive rate for the 3 common fetal trisomies (trisomies 21, 18, and 13). The potential advantages of noninvasive prenatal testing in twin pregnancies are even greater than in singletons, in particular lower need for invasive testing and consequent fetal loss rate. However, several organizations do not recommend cell-free DNA in twin pregnancies and call for larger prospective studies.

OBJECTIVE

In response to this, we undertook a large prospective multicenter study to establish the screening performance of cell-free DNA for the 3 common trisomies in twin pregnancies. Moreover, we combined our data with that reported in published studies to obtain the best estimate of screening performance.

STUDY DESIGN

This was a prospective multicenter blinded study evaluating the screening performance of cell-free DNA in maternal plasma for the detection of fetal trisomies in twin pregnancies. The study took place in 6 fetal medicine centers in England, United Kingdom. The primary outcome was the screening performance and test failure rate of cell-free DNA using next generation sequencing (the IONA test). Maternal blood was taken at the time of (or after) a conventional screening test. Data were collected at enrolment, at any relevant invasive testing throughout pregnancy, and after delivery until the time of hospital discharge. Prospective detailed outcome ascertainment was undertaken on all newborns. The study was undertaken and reported according to the Standards for Reporting of Diagnostic Accuracy Studies. A pooled analysis was also undertaken using our data and those in the studies identified by a literature search (MEDLINE, Embase, CENTRAL, Cochrane Library, and ClinicalTrials.gov) on June 6, 2020.

RESULTS

A total of 1003 women with twin pregnancies were recruited, and complete data with follow-up and reference data were available for 961 (95.8%); 276 were monochorionic and 685 were dichorionic. The failure rate was 0.31%. The mean fetal fraction was 12.2% (range, 3%-36%); all 9 samples with a 3% fetal fraction provided a valid result. There were no false-positive or false-negative results for trisomy 21 or trisomy 13, whereas there was 1 false-negative and 1 false-positive result for trisomy 18. The IONA test had a detection rate of 100% for trisomy 21 (n=13; 95% confidence interval, 75-100), 0% for trisomy 18 (n=1; 95% confidence interval, 0-98), and 100% for trisomy 13 (n=1; 95% confidence interval, 3-100). The corresponding false-positive rates were 0% (95% confidence interval, 0-0.39), 0.10% (95% confidence interval, 0-0.58), and 0% (95% confidence interval, 0-0.39), respectively. By combining data from our study with the 11 studies identified by literature search, the detection rate for trisomy 21 was 95% (n=74; 95% confidence interval, 90-99) and the false-positive rate was 0.09% (n=5598; 95% confidence interval, 0.03-0.19). The corresponding values for trisomy 18 were 82% (n=22; 95% confidence interval, 66-93) and 0.08% (n=4869; 95% confidence interval, 0.02-0.18), respectively. There were 5 cases of trisomy 13 and 3881 non-trisomy 13 pregnancies, resulting in a computed average detection rate of 80% and a false-positive rate of 0.13%.

CONCLUSION

This large multicenter study confirms that cell-free DNA testing is the most accurate screening test for trisomy 21 in twin pregnancies, with screening performance similar to that in singletons and very low failure rates (0.31%). The predictive accuracy for trisomies 18 and 13 may be less. However, given the low false-positive rate, offering first-line screening with cell-free DNA to women with twin pregnancy is appropriate in our view and should be considered a primary screening test for trisomy 21 in twins.

Associations of IVF singleton birthweight and gestation with clinical treatment and laboratory factors: a multicentre cohort study

STUDY QUESTION

Do IVF treatment and laboratory factors affect singleton birthweight (BW)?

SUMMARY ANSWER

BWs of IVF-conceived singleton babies are increasing with time, but we cannot identify the specific treatment factors responsible.

WHAT IS KNOWN ALREADY

IVF-conceived singleton babies from fresh transfers have slightly lower BW than those conceived naturally, whilst those from frozen embryo transfer (FET) cycles are heavier and comparable to naturally conceived offspring. Our recent studies have shown that BW varies significantly between different IVF centres, and in a single centre, is also increasing with time, without a corresponding change in BWs of naturally conceived infants. Although it is likely that factors in the IVF treatment cycle, such as hormonal stimulation or embryo laboratory culture conditions, are associated with BW differences, our previous study designs were not able to confirm this.

STUDY DESIGN, SIZE, DURATION

Data relating to BW outcomes, IVF treatment and laboratory parameters were collated from pre-existing electronic records in five participating centres for all singleton babies conceived between August 2007 and December 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Seven thousand, five hundred and eighty-eight births, 6207 from fresh and 1381 from FET. Infants with severe congenital abnormalities were excluded. The primary outcome of gestation-adjusted BW and secondary outcomes of unadjusted BW and gestation were analysed using multivariable regression models with robust standard errors to allow for the correlation between infants with the same mother. The models tested treatment factors allowing for confounding by centre, time and patient characteristics. A similar matched analysis of a subgroup of 379 sibling pairs was also performed.

MAIN RESULTS AND THE ROLE OF CHANCE

No significant associations of birth outcomes with IVF embryo culture parameters were seen independent of clinic or time, including embryo culture medium, incubator type or oxygen level, although small differences cannot be ruled out. We did not detect any significant differences associated with hormonal stimulation in fresh cycles or hormonal synchronization in FET cycles. Gestation-adjusted BW increased by 13.4 (95% CI 0.6-26.1) g per year over the period of the study, and babies born following FET were 92 (95% CI 57-128) g heavier on average than those from the fresh transfer.

LIMITATIONS, REASONS FOR CAUTION

Although no specific relationships have been identified independent of clinic and time, the confidence intervals remain large and do not exclude clinically relevant effect sizes. As this is an observational study, residual confounding may still be present.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrates the potential for large scale analysis of routine data to address critical questions concerning the long-term implications of IVF treatment, in accordance with the Developmental Origins of Health and Disease hypothesis. However, much larger studies, at a national scale with sufficiently detailed data, are required to identify the treatment parameters associated with differences in BW or other relevant outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the EU FP7 project grant, EpiHealthNet (FP7-PEOPLE-2012-ITN-317146). No competing interests were identified.

TRIAL REGISTRATION NUMBER

N/A.

Can information regarding the index stillbirth determine risk of adverse outcome in a subsequent pregnancy? Findings from a single-center cohort study

INTRODUCTION

Women with a history of stillbirth have an almost five-fold increased risk of stillbirth in a subsequent pregnancy, as well as increased risk of other adverse maternal and neonatal outcomes. The reasons for this association are not well understood but could relate to recurrent causes. We aimed to determine whether information from the time of index stillbirth, including cause, is associated with outcome of a subsequent pregnancy.

MATERIAL AND METHODS

A retrospective cohort study was conducted at a UK tertiary maternity center. Cases were included if stillbirth was investigated, subsequent pregnancy care was provided, and the birth occurred in the same unit. Data on maternal characteristics, findings of investigations, and classification of death using the ReCoDe system were extracted, and logistic regression was performed to determine whether these factors were associated with adverse outcome in the subsequent pregnancy.

RESULTS

In this cohort (n = 266), there were 69 adverse outcomes, including three perinatal deaths. Preterm delivery (16.2%) and birthweight <10th centile (12.4%) were the most common adverse outcomes. Of the preterm births, 69.8% were iatrogenic and 47% of these were due to abnormalities of fetal growth. On multivariate analysis women with a preexisting medical condition (adjusted odds ratio [aOR] 2.12, 95% CI 1.10-4.12) and those who smoked in their subsequent pregnancy (aOR 6.80, 95% CI 1.99-23.30) were at increased risk of adverse outcome. Neither ReCoDe classification of stillbirth (P = .61) nor gestation of stillbirth (P = .36) were associated with subsequent pregnancy outcome. Placental histopathological findings of maternal vascular malperfusion (aOR 11.34, 95% CI 2.20-58.62), fetal vascular malperfusion (aOR 9.27, 95% CI 1.09-78.82), and chorioamnionitis (aOR 6.35, 95% CI 1.16-34.78) in the index stillbirth were associated with adverse outcome in subsequent pregnancy. These associations were independent of maternal characteristics.

CONCLUSIONS

Placental examination at time of stillbirth is important, as certain placental disorders inform the risk of adverse outcome in subsequent pregnancy. In this cohort, information regarding maternal characteristics and classification of cause of stillbirth do not provide significant prognostic information about the risk of adverse outcome in subsequent pregnancies. Optimal management of maternal medical disorders and access to smoking cessation are essential.

Postnatal Enalapril to Improve Cardiovascular Function Following Preterm Preeclampsia (PICk-UP):: A Randomized Double-Blind Placebo-Controlled Feasibility Trial

Hypertensive disease in pregnancy is associated with future cardiovascular disease and, therefore, provides an opportunity to identify women who could benefit from targeted interventions aimed at reducing cardiovascular morbidity. This study focused on the highest-risk group, women with preterm preeclampsia, who have an 8-fold risk of death from future cardiovascular disease. We performed a single-center feasibility randomized controlled trial of 6 months' treatment with enalapril to improve postnatal cardiovascular function. Echocardiography and hemodynamic measurements were performed at baseline (<3 days), 6 weeks, and 6 months postdelivery on 60 women. At randomization, 88% of women had diastolic dysfunction, and 68% had concentric remodeling/hypertrophy. No difference was seen in total vascular resistance (P=0.59) or systolic function (global longitudinal strain: P=0.14) between groups at 6 months. However, women treated with enalapril had echocardiographic measurements consistent with improved diastolic function (E/E'[the ratio of early mitral inflow velocity and early mitral annular diastolic velocity]: P=0.04) and left ventricular remodeling (relative wall thickness: P=0.01; left ventricular mass index: P=0.03) at 6 months, compared with placebo. Urinary enalapril was detectable in 85% and 63% of women in the enalapril arm at 6 weeks and 6 months, respectively. All women responded positively to taking enalapril in the future. Our study confirmed acceptability and feasibility of the study protocol with a recruitment to completion rate of 2.2 women per month. Importantly, postnatal enalapril treatment was associated with improved echocardiographic measurements; these early improvements have the potential to reduce long-term cardiovascular disease risk. A definitive, multicenter randomized controlled trial is now required to confirm these findings. Registration- URL: https://www.clinicaltrials.gov; Unique identifier: NCT03466333.

The impact of IVF on birthweight from 1991 to 2015: a cross-sectional study

STUDY QUESTION

Has birthweight (BW) changed over time among IVF-conceived singletons?

SUMMARY ANSWER

Singleton BW has increased markedly over the past 25 years.

WHAT IS KNOWN ALREADY

IVF conceived singletons have had a higher incidence of low BW compared to spontaneously conceived singletons, and this has raised concerns over long-term increased risks of cardio-metabolic disease. However, few causal links between IVF procedures and BW have been robustly established, and few studies have examined whether BW has changed over time as IVF techniques have developed.

STUDY DESIGN, SIZE, DURATION

A total of 2780 live born singletons conceived via IVF or ICSI treated in the reproductive medicine department of a single publicly funded tertiary care centre between 1991 and 2015 were included in this retrospective study. The primary outcome measure was singleton BW adjusted for gestational age, maternal parity and child gender. Multivariable linear regression models were used to estimate the associations between patient prognostic factors and IVF treatment procedures with adjusted BW.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All singletons conceived at the centre following IVF/ICSI using the mother's own oocytes, and non-donated fresh or frozen/thawed embryos with complete electronic data records, were investigated. Available electronic records were retrieved from the Human Fertilization and Embryology Authority for dataset collation. Multiple linear regression analysis was used to evaluate associations between IVF treatment parameters and BW, after adjusting for the year of treatment and patient characteristics and pregnancy factors.

MAIN RESULTS AND THE ROLE OF CHANCE

In the primary multivariable model, singleton BW increased by 7.4 g per year (95% CI: 3.2-11.6 g, P = 0.001), an increase of close to 180 g throughout the 25-year period after accounting for gestational age, maternal parity, child gender, IVF treatment parameters, patient prognostic characteristics and pregnancy factors. Fresh and frozen embryo transfer-conceived singletons showed a similar increase in BW. Frozen/thawed embryo transfer conceived singletons were on average 53 g heavier than their fresh embryo conceived counterparts (95% CI: 3.7-103.3 g, P = 0.035).

LIMITATIONS, REASONS FOR CAUTION

The independent variables included in the study were limited to those that have been consistently recorded and stored electronically over the past two decades.

WIDER IMPLICATIONS OF THE FINDINGS

There has been a progressive BW increase in IVF singletons over time in one large centre with consistent treatment eligibility criteria. Such a change is not seen in the general population of live born singletons in the UK or other developed countries, and seems to be specific to this IVF population. This may be a reflection of changes in practice such as undisturbed extended embryo culture to the blastocyst stage, optimized commercial culture media composition, single embryo transfer and ICSI. Moreover, singletons conceived from frozen/thawed embryos had higher birth weights when compared to their fresh embryo transfer counterparts. The causal pathway is unknown; however, it could be due to the impact on embryos of the freeze/thaw process, self-selection of embryos from couples who produce a surplus of embryos, and/or embryo replacement into a more receptive maternal environment.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the EU FP7 project grant, EpiHealthNet (FP7-PEOPLE-2012-ITN-317146). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

The impact of selected embryo culture conditions on ART treatment cycle outcomes: a UK national study

STUDY QUESTION

Are selected embryo culture conditions namely media, oxygen level, and incubator type, associated with IVF live birth rate (LBR) and the health of singleton offspring at birth?

SUMMARY ANSWER

There were statistically significant differences in LBR between the eight culture media systems analysed; however, none of the embryo culture factors showed statistically significant associations with birth weight (BW) in multivariable regression analyses.

WHAT IS KNOWN ALREADY

In clinical ART culture media is the initial environment provided for the growth of human embryos. Pre-implantation development is a critical period of developmental plasticity, which could have long-lasting effects on offspring growth and health. Although some studies have shown an impact of culture medium type on BW, the interaction between culture medium type and associated culture conditions on both treatment success rates (LBR) and offspring BW is largely unexplored. This study aimed to examine these factors in a large multicentre national survey capturing the range of clinical practice.

STUDY DESIGN, SIZE, DURATION

In this cross-sectional study, data from a survey circulated to all UK IVF clinics requesting information regarding culture medium type, incubator type, and oxygen level used in ART between January 2011 and December 2013 were merged with routinely recorded treatment and outcome data held in the Human Fertilisation and Embryology Authority Register up to the end of 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Forty-six (62%) UK clinics responded to the survey. A total of 75 287 fresh IVF/ICSI cycles were captured, including 18 693 singleton live births. IVF success (live birth, singleton or multiple; LB), singleton gestation and singleton gestation-adjusted BW were analysed using logistic and linear regression models adjusting for patient/treatment characteristics and clinic-specific effects.

MAIN RESULTS AND THE ROLE OF CHANCE

Culture medium type was shown to have some impact on LBR (multivariable logistic regression, (MRL); post-regression Wald test, P < 0.001), but not on BW (MLR; post-regression Wald test, P = 0.215). However, blastocyst culture had the largest observed effect on odds of LBR (odds ratio (OR) = 1.35, CI: 1.29–1.42), increased the risk of pre-term birth even when controlling for oxygen tension (MLR; OR = 1.42, CI: 1.23–1.63), and gestation-adjusted BW (MLR, β = 38.97 g, CI: 19.42–58.53 g) when compared to cleavage-stage embryo culture. We noted a very strong effect of clinic site on both LBR and BW, thus confounding between treatment practices and clinic site may have masked the effect of culture conditions.

LIMITATIONS, REASONS FOR CAUTION

Larger datasets with more inter-centre variation are also needed, with key embryo culture variables comprehensively recorded in national treatment registries.

WIDER IMPLICATIONS OF THE FINDINGS

This study is the largest investigation of laboratory environmental effects in IVF on both LBR and singleton BW. Our findings largely agree with the literature, which has failed to show a consistent advantage of one culture media type over another. However, we noted some association of LBR with medium type, and the duration of embryo exposure to laboratory conditions (blastocyst culture) was associated with both LBR and singleton health at birth. Because of the strong effect of clinic site noted, further randomized controlled trials are needed in order to reliably determine the effect of embryo culture on IVF success rates and the growth and health of subsequent offspring.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the EU FP7 project grant EpiHealthNet (FP7-PEOPLE-2012-ITN -317 146). The authors have no competing interests to declare.

Effect of sildenafil on maternal hemodynamics in pregnancies complicated by severe early-onset fetal growth restriction: planned subgroup analysis from a multicenter randomized placebo-controlled double-blind trial

OBJECTIVES

Fetal growth restriction (FGR) is associated with maternal cardiovascular changes. Sildenafil, a phosphodiesterase type-5 inhibitor, potentiates the actions of nitric oxide, and it has been suggested that it alters maternal hemodynamics, potentially improving placental perfusion. Recently, the Dutch STRIDER trial was stopped prematurely owing to excess neonatal mortality secondary to pulmonary hypertension. The main aim of this study was to investigate the effect of sildenafil on maternal hemodynamics in pregnancies with severe early-onset FGR.

METHODS

This was a cardiovascular substudy within a UK multicenter, placebo-controlled trial, in which 135 women with a singleton pregnancy and severe early-onset FGR (defined as a combination of estimated fetal weight or abdominal circumference below the 10^th centile and absent/reversed end-diastolic flow in the umbilical artery on Doppler velocimetry, diagnosed between 22 + 0 and 29 + 6 weeks' gestation) were assigned randomly to receive either 25 mg sildenafil three times daily or placebo until 32 + 0 weeks' gestation or delivery. Maternal blood pressure (BP), heart rate (HR), augmentation index, pulse wave velocity (PWV), cardiac output, stroke volume (SV) and total peripheral resistance were recorded before randomization, 1-2 h and 48-72 h post-randomization, and 24-48 h postnatally. For continuous data, analysis was performed using repeated measures ANOVA methods including terms for timepoint, treatment allocation and their interaction.

RESULTS

Included were 134 women assigned randomly to sildenafil (n = 69) or placebo (n = 65) who had maternal BP and HR recorded at baseline. At 1-2 h post-randomization, compared with baseline values, sildenafil increased maternal HR by 4 bpm more than did placebo (mean difference, 5.00 bpm (95% CI, 1.00-12.00 bpm) vs 1.25 bpm (95% CI, -5.38 to 7.88 bpm); P = 0.004) and reduced systolic BP by 1 mmHg more (mean difference, -4.13 mmHg (95% CI, -9.94 to 1.44 mmHg) vs -2.75 mmHg (95% CI, -7.50 to 5.25 mmHg); P = 0.048). Even after adjusting for maternal mean arterial pressure, sildenafil reduced aortic PWV by 0.60 m/s more than did placebo (mean difference, -0.90 m/s (95% CI, -1.31 to -0.51 m/s) vs -0.26 m/s (95% CI, -0.75 to 0.59 m/s); P = 0.001). Sildenafil was associated with a non-significantly greater decrease in SV index after 1-2 h post-randomization than was placebo (mean difference, -5.50 mL/m² (95% CI, -11.00 to -0.50 mL/m² ) vs 0.00 mL/m² (95% CI, -5.00 to 4.00 mL/m² ); P = 0.056).

CONCLUSIONS

Sildenafil in a dose of 25 mg three times daily increases HR, reduces BP and reduces arterial stiffness in pregnancies complicated by severe early-onset FGR. These changes are short term, modest and consistent with the anticipated vasodilatory effect. They have no short- or long-term clinical impact on the mother. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Intra-placental arterial Doppler: A marker of fetoplacental vascularity in late-onset placental disease?

INTRODUCTION

Late-gestation adverse pregnancy outcome is associated with reduced placental villous vascularity but rarely with a frankly abnormal umbilical artery Doppler waveform. The clinical utility of umbilical artery Doppler velocimetry in late gestation is limited by poor understanding of what aspect(s) of placental structure and function the impedance reflects. We hypothesized that placental arterial circulation impedance reflects placental vascularity and arterial function.

MATERIAL AND METHODS

This was a secondary analysis of data from the FEMINA2 study, a study of pregnancy outcome after reduced fetal movement. Forty-three pregnancies that delivered within 7 days of ultrasound assessment were examined. Impedance was quantified by pulsatility index (PI) from umbilical, chorionic plate arteries, and intra-placental arteries. Site-specific PI was compared with villous vascularity (CD31 immunostaining) and placental arterial function (wire myography) by regression analysis (P < .01) where factor analysis suggested potential co-variance (Eigen value > 2).

RESULTS

Pulsatility index decreased with proximity to the placental microvasculature (P < .0001). Intra-placental artery PI correlated significantly with vessel number (R²  = 0.40, P = .0007). No significant relations between umbilical or chorionic plate artery PI and villous vascularity were found (P ≥ .11 and P ≥ .042). No significant co-variance was suggested between PI at any Doppler sampling site and ex vivo placental arterial function indices. Measurement reliability (intraclass correlation coefficient) was highest in the umbilical artery (PI 0.75 and 0.50 for intra- and interoperator reliability, respectively) and lowest in the intra-placental arteries (PI 0.55 and 0.41, respectively). Systematic bias in umbilical artery PI was observed between observers, but not at other Doppler sampling sites.

CONCLUSIONS

More vascular placentas ex vivo are associated with reduced intra-placental artery Doppler impedance in utero. Although umbilical (but not intra-placental) artery Doppler PI is associated with adverse outcome after reduced fetal movement, this predictive ability does not appear to be through assessment of placental vascularity or chorionic plate arterial function. The inferior reliability of intra-placental artery Doppler, although similar to previously published reliability of umbilical artery Doppler, impairs its ability to detect subtle differences in placental vascularity, and must be significantly improved before it could be considered a clinically useful test.

Placental MRI and its application to fetal intervention

OBJECTIVE

Magnetic resonance imaging (MRI) of placental invasion has been part of clinical practice for many years. The possibility of being better able to assess placental vascularization and function using MRI has multiple potential applications. This review summarises up-to-date research on placental function using different MRI modalities.

METHOD

We discuss how combinations of these MRI techniques have much to contribute to fetal conditions amenable for therapy such as singletons at high risk for fetal growth restriction (FGR) and monochorionic twin pregnancies for planning surgery and counselling for selective growth restriction and transfusion conditions.

RESULTS

The whole placenta can easily be visualized on MRI, with a clear boundary against the amniotic fluid, and a less clear placental-uterine boundary. Contrasts such as diffusion weighted imaging, relaxometry, blood oxygenation level dependent MRI and flow and metabolite measurement by dynamic contrast enhanced MRI, arterial spin labeling, or spectroscopic techniques are contributing to our wider understanding of placental function.

CONCLUSION

The future of placental MRI is exciting, with the increasing availability of multiple contrasts and new models that will boost the capability of MRI to measure oxygen saturation and placental exchange, enabling examination of placental function in complicated pregnancies.

Evaluating the accuracy and precision of sonographic fetal weight estimation models in extremely early-onset fetal growth restriction

INTRODUCTION

Birthweight is a critical predictor of survival in extremely early-onset fetal growth restriction (diagnosed pre-28 weeks' gestation, with abnormal umbilical/uterine artery Doppler waveforms), therefore accurate fetal weight estimation is a crucial component of antenatal management. Currently available sonographic fetal weight estimation models were predominantly developed in populations of mixed gestational age and varying fetal weights, but not specifically tested within the context of extremely early-onset fetal growth restriction. This study aimed to determine the accuracy and precision of fetal weight estimation in this population and investigate whether model performance is affected by other factors.

MATERIAL AND METHODS

Cases where a growth scan was performed within 48 hours of delivery (n = 65) were identified from a cohort of extremely early-onset fetal growth-restricted pregnancies at a single tertiary maternity center (n = 159). Fetal biometry measurements were used to calculate estimated fetal weight using 21 previously published models. Systematic and random errors were calculated for each model and used to identify the best performing model, which in turn was used to explore the relationship between error and gestation, estimated fetal weight, fetal presentation, fetal asymmetry and amniotic fluid volume.

RESULTS

Both systematic (median 8.2%; range -44.1 to 49.5%) and random error (median 11.6%; range 9.7-23.8%) varied widely across models. The best performing model was Hadlock head circumference-abdominal circumference-femur length (HC-AC-FL), regardless of gestational age, fetal size, fetal presentation or asymmetry, with an overall systematic error of 1.5% and random error of 9.7%. Despite this, it only calculated the estimated fetal weight within 10% of birthweight in 64.6% of cases. There was a weak negative relation between mean percentage error with Hadlock HC-AC-FL and amniotic fluid volume, suggesting fetal weight is overestimated at lower liquor volumes and underestimated at higher liquor volumes (P = 0.002, adjusted R²  = 0.08).

CONCLUSIONS

Hadlock HC-AC-FL is the most accurate model currently available to estimate fetal weight in extremely early-onset fetal growth restriction independent of gestation or fetal size, asymmetry or presentation. However, for 35.4% of cases in this study, estimated fetal weight calculated using this model deviates by more than 10% from birthweight, highlighting a need for an improved model.

A prediction model for short-term neonatal outcomes in severe early-onset fetal growth restriction

BACKGROUND

Severe early-onset fetal growth restriction (FGR) predisposes to fetal death, neonatal death, neonatal morbidity and neurodisability. The use of placental biomarkers has been proposed for risk stratification in pre-eclampsia, but they could be equally useful in fetal growth restriction in aiding management.

OBJECTIVE

To determine the efficacy of angiogenic biomarkers at predicting adverse pregnancy outcome in severe early-onset fetal growth restriction.

STUDY DESIGN

This is a secondary analysis of the multicentre, placebo-controlled STRIDER UK randomised controlled trial of singleton pregnancies with severe early-onset fetal growth restriction. Women with FGR pregnancies between 22⁺⁰ and 29⁺⁶ weeks of gestation were randomly assigned to receive either sildenafil 25 mg three times daily or placebo until 32⁺⁰ weeks' gestation or delivery. We developed prediction models based upon maternal demographics (age, parity, blood pressure, preeclampsia, gestational hypertension), fetal biometric (estimated fetal weight) and Doppler measurements (Middle Cerebral Artery (MCA), Umbilical Artery (UA)) and maternal angiogenic biomarkers [placental growth factor (PlGF), soluble endoglin (sEng), soluble fms-like tyrosine kinase 1 (sFlt-1) and sFlt-1:PlGF ratio) using both univariate and multivariate analysis.

RESULTS

A complete data set was available for 105 of 135 randomised women. Multivariate regression analysis identified estimated fetal weight (EFW) and sFlt-1:PlGF as independent predictors of livebirth (EFW OR: 1.01 (1.008, 1.021); p < 0.001 and lower sFlt-1:PlGF ratio OR: 0.53 (0.284, 0.994); p = 0.048) and overall survival (EFW OR: 1.01 (1.006, 1.015); p < 0.001 and lower sFlt-1/PlGF ratio OR: 0.51 (0.286, 0.904); p = 0.021). EFW was a consistent predictor for all outcomes other than gestation at delivery. sFlt-1:PlGF ratio was a consistent predictor for all outcomes other than neonatal morbidity.

CONCLUSIONS

In severe early-onset FGR pregnancies livebirth and overall survival can be predicted using a model involving EFW and sFlt-1:PlGF ratio. This model require validation in a larger cohort but may allow informed decision making about pregnancy management, especially in previable cases.

Parental decision-making following a prenatal diagnosis that is lethal, life-limiting, or has long term implications for the future child and family: a meta-synthesis of qualitative literature

BACKGROUND

Information on the factors influencing parents' decision-making process following a lethal, life-limiting or severely debilitating prenatal diagnosis remains deficient. A comprehensive systematic review and meta-synthesis was conducted to explore the influencing factors for parents considering termination or continuation of pregnancy following identification of lethal, life-limiting or severely debilitating fetal abnormalities.

METHODS

Electronic searches of 13 databases were conducted. These searches were supplemented by hand-searching Google Scholar and bibliographies and citation tracing. Thomas and Harden's (2008) thematic synthesis method was used to synthesise data from identified studies.

RESULTS

Twenty-four papers were identified and reviewed, but two papers were removed following quality assessment. Three main themes were identified through systematic synthesis. Theme 1, entitled 'all life is precious', described parents' perception of the importance of the fetus' life, a fatalistic view of their situation alongside moral implications as well as the implications decisions would have on their own life, in consideration of previous life experiences. Theme 2 ('hope for a positive outcome') contained two sub-themes which considered the parent's own imagined future and the influence of other people's experiences. Finally, Theme 3 ('a life worth living') presented three sub-themes which may influence their parental decision-making: These described parental consideration of the quality of life for their unborn child, the possibility of waiting to try for another pregnancy, and their own responsibilities and commitments.

CONCLUSION

The first review to fully explore parental decision-making process following lethal, life-limiting, or severely debilitating prenatal diagnosis provided novel findings and insight into which factors influenced parents' decision-making process. This comprehensive and systematic review provides greater understanding of the factors influential on decision-making, such as hope, morality and potential implications on their own and other's quality of life, will enable professionals to facilitate supported decision-making, including greater knowledge of the variables likely to influence parental choices.

Women's lived experiences of a prenatal diagnosis of fetal growth restriction at the limits of viability: An interpretative phenomenological study

OBJECTIVES

The research team aimed to understand women's lived experiences during pregnancies with poor prognosis following prenatal detection of Fetal Growth Restriction at the limits of viability (FGRLV).

METHODS

Qualitative interviews with six women who had attended a specialist service following a prenatal diagnosis of FGRLV were conducted. The interview data were analysed using interpretative phenomenological analysis.

FINDINGS

Three superordinate themes alongside thirteen subthemes were identified. Theme 1 described 'a fine line between supportive and unhelpful' care experiences. A second theme of 'understanding the situation and decisions to be made' described how women faced many uncertainties. The final theme of 'parental responsibility' reflected how women imagined their futures to have been, exploring their embodied parental role and connection to their unborn or young child.

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

Women highlighted the importance of maternal healthcare teams providing clear information and reassurance to them. They also reported that prior experiences were important to them in influencing their perception of that pregnancy. Furthermore, women reflected on their desperation for a positive outcome. Understanding these factors can enable maternal healthcare teams to facilitate informed decision-making and provide individualised emotional support for women. Our findings will enable maternal care teams to better support women in similar clinical situations.

Antenatal placental assessment in the prediction of adverse pregnancy outcome after reduced fetal movement

OBJECTIVE

To assess the value of in utero placental assessment in predicting adverse pregnancy outcome after reported reduced fetal movements (RFM).

METHOD

A non-interventional prospective cohort study of women (N = 300) with subjective RFM at ≥28 weeks' gestation in singleton non-anomalous pregnancies at a UK tertiary maternity hospital. Clinical, sonographic (fetal weight, placental size and maternal, fetal and placental arterial Doppler) and biochemical (maternal serum hCG, hPL, progesterone, PlGF and sFlt-1) assessment was conducted. Multiple logistic regression identified combinations of measurements (models) most predictive of adverse pregnancy outcome (perinatal mortality, birth weight <10th centile, five minute Apgar score <7, umbilical arterial pH <7.1 or base excess <-10, neonatal intensive care admission). Models were compared by test performance characteristics (ROC curve, sensitivity, specificity, positive/negative predictive value, positive/negative likelihood ratios) against baseline care (estimated fetal weight centile, amniotic fluid index and gestation at presentation).

RESULTS

61 (20.6%) pregnancies ended in adverse outcome. Models incorporating PlGF/sFlt-1 ratio and umbilical artery free loop Doppler impedance demonstrated modest improvement in ROC area for adverse outcome (baseline care 0.69 vs. proposed models 0.73-0.76, p<0.05). However, there was little improvement in other test characteristics (baseline vs. best proposed model: sensitivity 21.7% [95% confidence interval 13.1-33.6] vs. 35.8%% [24.4-49.3], specificity 96.6% [93.4-98.3] vs. 94.7% [90.7-97.0], PPV 61.9% [40.9-79.3] vs. 63.3% [45.5-78.1], NPV 82.8% [77.9-86.8] vs. 85.2% [80.0-89.2], positive LR 6.3 [2.8-14.6] vs. 6.7 [3.4-3.3], negative LR 0.81 [0.71-0.93] vs. 0.68 [0.55-0.83]) and wide confidence intervals. Negative post-test probability remained high (16.7% vs. 14.0%).

CONCLUSION

Antenatal placental assessment may improve identification of RFM pregnancies at highest risk of adverse pregnancy outcome but further work is required to understand and refine currently available outcome definitions and diagnostic techniques to improve clinical utility.

Placenta Imaging Workshop 2018 report: Multiscale and multimodal approaches

The Centre for Medical Image Computing (CMIC) at University College London (UCL) hosted a two-day workshop on placenta imaging on April 12th and 13th 2018. The workshop consisted of 10 invited talks, 3 contributed talks, a poster session, a public interaction session and a panel discussion about the future direction of placental imaging. With approximately 50 placental researchers in attendance, the workshop was a platform for engineers, clinicians and medical experts in the field to network and exchange ideas. Attendees had the chance to explore over 20 posters with subjects ranging from the movement of blood within the placenta to the efficient segmentation of fetal MRI using deep learning tools. UCL public engagement specialists also presented a poster, encouraging attendees to learn more about how to engage patients and the public with their research, creating spaces for mutual learning and dialogue.

A mixed-methods evaluation of continuous electronic fetal monitoring for an extended period

INTRODUCTION

Continuous fetal monitoring is used to objectively record the fetal heart rate and fetal activity over an extended period of time; however, its feasibility and acceptability to women is currently unknown. The study addressed the hypothesis that continuous fetal monitoring is feasible and acceptable to pregnant women.

MATERIAL AND METHODS

Pregnant participants (n = 22) were monitored using a continuous fetal electrocardiography device, the Monica AN24. Signal quality, duration of recording and cardiotocography findings were correlated with maternal and fetal factors. Participants' change in anxiety before and after monitoring was assessed using validated questionnaires. Participants' experiences were explored through a questionnaire (n = 20) and semi-structured interview (n = 13).

RESULTS

Recordings were successfully obtained in 19 of the 22 participants (86.3%). The mean recording quality of fetal heart rate was 69.0% (range 17.4%-99.4%) and maternal heart rate was 99.0% (90.9%-100.0%). Recording quality was positively correlated with gestational age (P = 0.05) and negatively correlated with uterine activity and maternal movement (P < 0.001). Overall, participants were satisfied with their experience of continuous fetal monitoring; 30% considered it preferable to intermittent monitoring. Continuous fetal monitoring did not significantly increase maternal anxiety, with a trend towards a reduction in Pregnancy Specific Anxiety score (P = 0.07). Qualitative analysis grouped women's responses into three themes: (a) reassurance and anxiety, (b) the physical device and (c) future developments in continuous fetal monitoring.

CONCLUSIONS

Continuous fetal monitoring is a feasible and acceptable form of monitoring to pregnant women although further practical improvements could be incorporated. Further research is required to assess the ability of continuous fetal monitoring to detect fetal compromise.

Human placental oxygenation in late gestation: experimental and theoretical approaches

The placenta is crucial for life. It is an ephemeral but complex organ acting as the barrier interface between maternal and fetal circulations, providing exchange of gases, nutrients, hormones, waste products and immunoglobulins. Many gaps exist in our understanding of the detailed placental structure and function, particularly in relation to oxygen handling and transfer in healthy and pathological states in utero. Measurements to understand oxygen transfer in vivo in the human are limited, with no general agreement on the most appropriate methods. An invasive method for measuring partial pressure of oxygen in the intervillous space through needle electrode insertion at the time of Caesarean sections has been reported. This allows for direct measurements in vivo whilst maintaining near normal placental conditions; however, there are practical and ethical implications in using this method for determination of placental oxygenation. Furthermore, oxygen levels are likely to be highly heterogeneous within the placenta. Emerging non-invasive techniques, such as MRI, and ex vivo research are capable of enhancing and improving current imaging methodology for placental villous structure and increase the precision of oxygen measurement within placental compartments. These techniques, in combination with mathematical modelling, have stimulated novel cross-disciplinary approaches that could advance our understanding of placental oxygenation and its metabolism in normal and pathological pregnancies, improving clinical treatment options and ultimately outcomes for the patient.

IFPA meeting 2017 workshop report: Clinical placentology, 3D structure-based modeling of placental function, placental bed, and treating placental dysfunction

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2017 there were four themed workshops, all of which are summarized in this report. These workshops discussed new knowledge and technological innovations in the following areas of research: 1) placental bed; 2) 3D structural modeling; 3) clinical placentology; 4) treatment of placental dysfunction.

Maternal sildenafil for severe fetal growth restriction (STRIDER): a multicentre, randomised, placebo-controlled, double-blind trial

BACKGROUND

Severe early-onset fetal growth restriction can lead to a range of adverse outcomes including fetal or neonatal death, neurodisability, and lifelong risks to the health of the affected child. Sildenafil, a phosphodiesterase type 5 inhibitor, potentiates the actions of nitric oxide, which leads to vasodilatation of the uterine vessels and might improve fetal growth in utero.

METHODS

We did this superiority, placebo-controlled randomised trial in 19 fetal medicine units in the UK. We used random computer allocation (1:1) to assign women with singleton pregnancies between 22 weeks and 0 days' gestation and 29 weeks and 6 days' gestation and severe early-onset fetal growth restriction to receive either sildenafil 25 mg three times daily or placebo until 32 weeks and 0 days' gestation or delivery. We stratified women by site and by their gestational age at randomisation (before week 26 and 0 days or at week 26 and 0 days or later). We defined fetal growth restriction as a combination of estimated fetal weight or abdominal circumference below tenth percentile and absent or reversed end-diastolic blood flow in the umbilical artery on Doppler velocimetry. The primary outcome was the time from randomisation to delivery, measured in days. This study is registered with BioMed Central, number ISRCTN 39133303.

FINDINGS

Between Nov 21, 2014, and July 6, 2016, we recruited 135 women and randomly assigned 70 women to sildenafil and 65 women to placebo. We found no difference in the median randomisation to delivery interval between women assigned to sildenafil (17 days [IQR 7-24]) and women assigned to placebo (18 days [8-28]; p=0·23). Livebirths (relative risk [RR] 1·06, 95% CI 0·84 to 1·33; p=0·62), fetal deaths (0·89, 0·54 to 1·45; p=0·64), neonatal deaths (1·33, 0·54 to 3·28; p=0·53), and birthweight (-14 g,-100 to 126; p=0·81) did not differ between groups. No differences were found for any other secondary outcomes. Eight serious adverse events were reported during the course of the study (six in the placebo group and two in the sildenafil group); none of these were attributed to sildenafil.

INTERPRETATION

Sildenafil did not prolong pregnancy or improve pregnancy outcomes in severe early-onset fetal growth restriction and therefore it should not be prescribed for this indication outside of research studies with explicit participants' consent.

FUNDING

National Institute for Health Research and Medical Research Council.

Fractional fetal thigh volume in the prediction of normal and abnormal fetal growth during the third trimester of pregnancy

Background

Currently, 2-dimensional ultrasound estimation of fetal size rather than fetal growth is used to define fetal growth restriction, but single estimates in late pregnancy lack sensitivity and may identify small for gestational age rather than growth restriction. Single or longitudinal measures of 3-dimensional fractional thigh volume may address this problem.

Objective

We sought to derive normal values for 3-dimensional fractional thigh volume in the third trimester, determine if fractional thigh volume is superior to 2-dimensional ultrasound biometry alone for detecting fetal growth restriction, and determine whether individualized growth assessment parameters have the potential to identify fetal growth restriction remote from term delivery.

Study Design

This was a longitudinal prospective cohort study of 115 unselected pregnancies in a tertiary referral unit (St Mary’s Hospital, Manchester, United Kingdom). Standard 2-dimensional ultrasound biometry measurements were obtained, along with fractional thigh volume measurements (based on 50% of the femoral diaphysis length). Measurements were used to calculate estimated fetal weight (Hadlock). Individualized growth assessment parameters and percentage deviations in longitudinally measured biometrics were determined using a Web-based system (iGAP; http://iGAP.research.bcm.edu). Small for gestational age was defined <10th and fetal growth restriction <3rd customized birthweight centile. Logistic regression was used to compare estimated fetal weight (Hadlock), estimated fetal weight (biparietal diameter–abdominal circumference–fractional thigh volume), fractional thigh volume, and abdominal circumference for the prediction of small for gestational age or fetal growth restriction at birth. Screening performance was assessed using area under the receiver operating characteristic curve.

Results

There was a better correlation between fractional thigh volume and estimated fetal weight ((biparietal diameter–abdominal circumference–fractional thigh volume) obtained at 34-36 weeks with birthweight than between 2-dimensional biometry measures such as abdominal circumference and estimated fetal weight (Hadlock). There was also a modest improvement in the detection of both small for gestational age and fetal growth restriction using fractional thigh volume–derived measures compared to standard 2-dimensional measurements (area under receiver operating characteristic curve, 0.86; 95% confidence interval, 0.79–0.94, and area under receiver operating characteristic curve, 0.92; 95% confidence interval, 0.85–0.99, respectively).

Conclusion

Fractional thigh volume measurements offer some improvement over 2-dimensional biometry for the detection of late-onset fetal growth restriction at 34-36 weeks.

Intraexaminer and Interexaminer Variability in 3D Fetal Volume Measurements During the Second and Third Trimesters of Pregnancy

OBJECTIVES

To assess intraexaminer and interexaminer reliability of 3-dimensional fetal sonographic measurements.

METHODS

Three-dimensional fetal organ volumes (head, kidney, total thigh volume, and fractional thigh volume) were acquired during the second and third trimesters, with the addition of placental volume in the second trimester, by 2 different experienced, blinded sonographers. Fifty-eight fetuses were examined from 21 to 39 weeks' gestation. Intraexaminer and Interexaminer reliability was assessed with Bland-Altman plots, and their 95% limits of agreement and intraclass correlation coefficients.

RESULTS

The most significant interexaminer error was observed in the second-trimester kidney volume (95% limits of agreement, ± 110%), and the best agreement was for the third-trimester fractional thigh volume (95% limits of agreement, ± 25%) and second-trimester head volume (95% limits of agreement, -7%-25%). Second- and third-trimester intraclass correlation coefficient results were all greater than 0.75, apart from second-trimester kidney volume intraexaminer (0.374) and interexaminer (0.061) measurements, second-trimester placenta interexaminer measurements (0.390), and third-trimester kidney interexaminer measurements (0.647).

CONCLUSIONS

Three-dimensional fetal sonographic volumes of the head, kidney, total thigh, and placenta have limited reproducibility, and improvements in measurement techniques are needed before they can be used routinely to assess fetal growth. The 3-dimensional fractional thigh volume can be reliably obtained in the late third trimester.

Computational modelling of placental amino acid transfer as an integrated system

Placental amino acid transfer is essential for fetal development and its impairment is associated with poor fetal growth. Amino acid transfer is mediated by a broad array of specific plasma membrane transporters with overlapping substrate specificity. However, it is not fully understood how these different transporters work together to mediate net flux across the placenta. Therefore the aim of this study was to develop a new computational model to describe how human placental amino acid transfer functions as an integrated system. Amino acid transfer from mother to fetus requires transport across the two plasma membranes of the placental syncytiotrophoblast, each of which contains a distinct complement of transporter proteins. A compartmental modelling approach was combined with a carrier based modelling framework to represent the kinetics of the individual accumulative, exchange and facilitative classes of transporters on each plasma membrane. The model successfully captured the principal features of transplacental transfer. Modelling results clearly demonstrate how modulating transporter activity and conditions such as phenylketonuria, can increase the transfer of certain groups of amino acids, but that this comes at the cost of decreasing the transfer of others, which has implications for developing clinical treatment options in the placenta and other transporting epithelia.

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First computational model of placental amino acid transfer as an integrated system

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Increased activity of a transporter does not mean increased transfer to the fetus.

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Increasing transfer of certain amino acids can reduce the transfer of others.

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Amino acid composition as well as concentration determines transfer to the fetus.

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Modelling of phenylketonuria suggests inhibition by excess maternal phenylalanine.

Is There Evidence of Poorer Birth Outcomes for Mothers and Babies When the Most Senior Obstetrician Is Not On Site?

In this Perspective on the study by Hannah Knight and colleagues, Jenny Myers and Edward Johnstone consider the implications of negative findings in a variable setting in which adverse events are rare.

Phenylalanine transfer across the isolated perfused human placenta: an experimental and modeling investigation

Membrane transporters are considered essential for placental amino acid transfer, but the contribution of other factors, such as blood flow and metabolism, is poorly defined. In this study we combine experimental and modeling approaches to understand the determinants of [(14)C]phenylalanine transfer across the isolated perfused human placenta. Transfer of [(14)C]phenylalanine across the isolated perfused human placenta was determined at different maternal and fetal flow rates. Maternal flow rate was set at 10, 14, and 18 ml/min for 1 h each. At each maternal flow rate, fetal flow rates were set at 3, 6, and 9 ml/min for 20 min each. Appearance of [(14)C]phenylalanine was measured in the maternal and fetal venous exudates. Computational modeling of phenylalanine transfer was undertaken to allow comparison of the experimental data with predicted phenylalanine uptake and transfer under different initial assumptions. Placental uptake (mol/min) of [(14)C]phenylalanine increased with maternal, but not fetal, flow. Delivery (mol/min) of [(14)C]phenylalanine to the fetal circulation was not associated with fetal or maternal flow. The absence of a relationship between placental phenylalanine uptake and net flux of phenylalanine to the fetal circulation suggests that factors other than flow or transporter-mediated uptake are important determinants of phenylalanine transfer. These observations could be explained by tight regulation of free amino acid levels within the placenta or properties of the facilitated transporters mediating phenylalanine transport. We suggest that amino acid metabolism, primarily incorporation into protein, is controlling free amino acid levels and, thus, placental transfer.

Placental Features of Late-Onset Adverse Pregnancy Outcome

Objective

Currently, no investigations reliably identify placental dysfunction in late pregnancy. To facilitate the development of such investigations we aimed to identify placental features that differ between normal and adverse outcome in late pregnancy in a group of pregnancies with reduced fetal movement.

Methods

Following third trimester presentation with reduced fetal movement (N = 100), placental structure ex vivo was measured. Placental function was then assessed in terms of (i) chorionic plate artery agonist responses and length-tension characteristics using wire myography and (ii) production and release of placentally derived hormones (by quantitative polymerase chain reaction and enzyme linked immunosorbant assay of villous tissue and explant conditioned culture medium).

Results

Placentas from pregnancies ending in adverse outcome (N = 23) were ~25% smaller in weight, volume, length, width and disc area (all p<0.0001) compared with those from normal outcome pregnancies. Villous and trophoblast areas were unchanged, but villous vascularity was reduced (median (interquartile range): adverse outcome 10 (10–12) vessels/mm² vs. normal outcome 13 (12–15), p = 0.002). Adverse outcome pregnancy placental arteries were relatively insensitive to nitric oxide donated by sodium nitroprusside compared to normal outcome pregnancy placental arteries (50% Effective Concentration 30 (19–50) nM vs. 12 (6–24), p = 0.02). Adverse outcome pregnancy placental tissue contained less human chorionic gonadotrophin (20 (11–50) vs. 55 (24–102) mIU/mg, p = 0.007) and human placental lactogen (11 (6–14) vs. 27 (9–50) mg/mg, p = 0.006) and released more soluble fms-like tyrosine kinase-1 (21 (13–29) vs. 5 (2–15) ng/mg, p = 0.01) compared with normal outcome pregnancy placental tissue.

Conclusion

These data provide a description of the placental phenotype of adverse outcome in late pregnancy. Antenatal tests that accurately reflect elements of this phenotype may improve its prediction.

Dysregulated flow-mediated vasodilatation in the human placenta in fetal growth restriction

Increased vascular resistance and reduced fetoplacental blood flow are putative aetiologies in the pathogenesis of fetal growth restriction (FGR); however, the regulating sites and mechanisms remain unclear. We hypothesised that placental vessels dictate fetoplacental resistance and in FGR exhibit endothelial dysfunction and reduced flow-mediated vasodilatation (FMVD). Resistance was measured in normal pregnancies (n = 10) and FGR (n = 10) both in vivo by umbilical artery Doppler velocimetry and ex vivo by dual placental perfusion. Ex vivo FMVD is the reduction in fetal-side inflow hydrostatic pressure (FIHP) following increased flow rate. Results demonstrated a significant correlation between vascular resistance measured in vivo and ex vivo in normal pregnancy, but not in FGR. In perfused FGR placentas, vascular resistance was significantly elevated compared to normal placentas (58 ± 7.7 mmHg and 36.8 ± 4.5 mmHg, respectively; 8 ml min⁻¹; means ± SEM; P < 0.0001) and FMVD was severely reduced (3.9 ± 1.3% and 9.1 ± 1.2%, respectively). In normal pregnancies only, the highest level of ex vivo FMVD was associated with the lowest in vivo resistance. Inhibition of NO synthesis during perfusion (100 μm l-NNA) moderately elevated FIHP in the normal group, but substantially in the FGR group. Human placenta artery endothelial cells from FGR groups exhibited increased shear stress-induced NO generation, iNOS expression and eNOS expression compared with normal groups. In conclusion, fetoplacental resistance is determined by placental vessels, and is increased in FGR. The latter also exhibit reduced FMVD, but with a partial compensatory increased NO generation capacity. The data support our hypothesis, which highlights the importance of FMVD regulation in normal and dysfunctional placentation.

Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanisms mediating [¹⁴C]l-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that l-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [¹⁴C]l-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with l-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms.

Continuous objective recording of fetal heart rate and fetal movements could reliably identify fetal compromise, which could reduce stillbirth rates by facilitating timely management

Stillbirth currently affects approximately 1 in every 200 pregnancies in the United Kingdom. Fetuses may exhibit signs of compromise as part of a stress response before stillbirth, including reduced fetal movements (RFM) and fetal heart rate (FHR) alterations. At present, and despite widespread use, current fetal monitoring is not associated with a reduction in perinatal mortality rate (PMR) as signs of fetal compromise are not adequately detected. This may be attributed to inaccuracies resulting from manual interpretation of results or subjective assessment of fetal activity. In addition, signs of compromise often occur only hours or days before fetal death, so may be missed by current monitoring methods, which are performed intermittently. A significant consideration is that correct identification of these signs and consequent intervention can result in the delivery of a healthy baby, thus preventing stillbirth. A hypothesis is presented, proposing prompt detection of fetal compromise with the use of 24-hour continuous objective fetal monitoring. With focus placed on obtaining long-term FHR and fetal movement data, prior interest has been found in developing devices for this purpose. However, introduction into clinical practice has not been achieved. Investigation of the hypothesis will begin with the design of a device to record the mentioned parameters, followed by an appropriate validation process. Should development and testing be successful, an eventual comparison in PMR with the use of continuous fetal monitoring vs current monitoring would address the hypothesis. It is suggested that a timely yet reliable indication of fetal wellbeing obtained via long-term monitoring would allow prompt and appropriate obstetric intervention and consequently reduce PMR.

A randomised controlled trial comparing standard or intensive management of reduced fetal movements after 36 weeks gestation--a feasibility study

Background

Women presenting with reduced fetal movements (RFM) in the third trimester are at increased risk of stillbirth or fetal growth restriction. These outcomes after RFM are related to smaller fetal size on ultrasound scan, oligohydramnios and lower human placental lactogen (hPL) in maternal serum. We performed this study to address whether a randomised controlled trial (RCT) of the management of RFM was feasible with regard to: i) maternal recruitment and retention ii) patient acceptability, iii) adherence to protocol. Additionally, we aimed to confirm the prevalence of poor perinatal outcomes defined as: stillbirth, birthweight <10^th centile, umbilical arterial pH <7.1 or unexpected admission to the neonatal intensive care unit.

Methods

Women with RFM ≥36 weeks gestation were invited to participate in a RCT comparing standard management (ultrasound scan if indicated, induction of labour (IOL) based on consultant decision) with intensive management (ultrasound scan, maternal serum hPL, IOL if either result was abnormal). Anxiety was assessed by state-trait anxiety index (STAI) before and after investigations for RFM. Rates of protocol compliance and IOL for RFM were calculated. Participant views were assessed by questionnaires.

Results

137 women were approached, 120 (88%) participated, 60 in each group, 2 women in the standard group did not complete the study. 20% of participants had a poor perinatal outcome. All women in the intensive group had ultrasound assessment of fetal size and liquor volume vs. 97% in the standard group. 50% of the intensive group had IOL for abnormal scan or low hPL after RFM vs. 26% of controls (p < 0.01). STAI reduced for all women after investigations, but this reduction was greater in the standard group (p = 0.02). Participants had positive views about their involvement in the study.

Conclusion

An RCT of management of RFM is feasible with a low rate of attrition. Investigations decrease maternal anxiety. Participants in the intensive group were more likely to have IOL for RFM. Further work is required to determine the likely level of intervention in the standard care arm in multiple centres, to develop additional placental biomarkers and to confirm that the composite outcome is valid.

Trial registration

ISRCTN07944306

R1 and R2 * changes in the human placenta in response to maternal oxygen challenge

PURPOSE

Pregnancy complications such as preeclampsia and fetal growth restriction are sometimes thought to be caused by placental abnormalities associated with reduced oxygenation. Oxygen-enhanced MRI (R1 contrast) and BOLD MRI (R2 * contrast) have the potential to noninvasively investigate this oxygen environment at a range of gestational ages.

METHODS

Scanning was carried out at 1.5 T under maternal air and oxygen breathing in a single placental slice in 14 healthy pregnant subjects of gestational ages 21-37 weeks. We report R1 changes using a respiratory-triggered inversion recovery-turbo spin-echo sequence, which is sensitive to changes in PO2 , and R2 * changes using a breathhold multiple gradient-recalled echo sequence sensitive to changes in oxygen saturation.

RESULTS

Significant R1 increases (P < 0.005, paired t-test) and R2 * decreases (P < 0.0001, paired t-test) between air and oxygen breathing were demonstrated. ΔR1 decreased with gestational age (P < 0.0005, r = -0.835, Pearson correlation test). No significant effect of gestational age on R2 * change was observed.

CONCLUSION

The results demonstrate the feasibility of non-invasive investigation of placental oxygenation using MRI and the sensitivity of R1 oxygen-enhanced MRI to gestational age. The techniques have the potential to provide unique noninvasive biomarkers in compromised pregnancies.

IFPA Meeting 2011 workshop report I: Placenta: Predicting future health; roles of lipids in the growth and development of feto-placental unit; placental nutrient sensing; placental research to solve clinical problems--a translational approach

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, four of which are summarized in this report. These workshops related to both basic science and clinical research into placental growth and nutrient sensing and were divided into 1) placenta: predicting future health; 2) roles of lipids in the growth and development of feto-placental unit; 3) placental nutrient sensing; 4) placental research to solve clinical problems: a translational approach.

Epidermal growth factor and sphingosine-1-phosphate stimulate Na+/H+ exchanger activity in the human placental syncytiotrophoblast

The Na+/H+ exchanger (NHE) has a key role in intracellular pH ([pH]i) regulation of the syncytiotrophoblast in the human placenta and may have a role in the life cycle of this cell. In other cells the NHE (actually a family of up to 9 isoforms) is regulated by a variety of factors, but its regulation in the syncytiotrophoblast has not been studied. Here, we tested the hypotheses that EGF and sphingosine-1-phosphate (S1P), both of which affect trophoblast apoptosis and, in other cell types, NHE activity, stimulate syncytiotrophoblast NHE activity. Villous fragments from term human placentas were loaded with the pH-sensitive dye, BCECF. NHE activity was measured by following the recovery of syncytiotrophoblast [pH]i following an imposed acid load, in the presence and absence of EGF, S1P, and specific inhibitors of NHE activity. Both EGF and S1P caused a dose-dependent upregulation of NHE activity in the syncytiotrophoblast. These effects were blocked by amiloride 500 microM (a nonspecific NHE blocker) and HOE694 100 microM (NHE blocker with NHE1 and 2 isoform selectivity). Effects of EGF were also reduced by the NHE3 selective blocker S3226 (used at 1 microM). These data provide the first evidence that both EGF and S1P stimulate NHE activity in the syncytiotrophoblast; they appear to do so predominantly by activating the NHE1 isoform.

Multiple anti-apoptotic pathways stimulated by EGF in cytotrophoblasts

Epidermal growth factor (EGF) reduces apoptosis in primary cytotrophoblast (CT) in culture through two separate pathways: the extracellular signal related kinase (ERK) 1/2 and phosphatidyl inositol 3-kinase (PI-3 kinase) paths. Whether other pathways are involved in survival signalling is unknown. We here show that the c-Jun NH2 terminal kinase (JNK) and the mitogen activated kinase (MAPK) p38 are also activated by EGF as seen by increases in JNK and p38 phosphorylation. However, inhibition of JNK phosphorylation with the specific inhibitor SP600125 increases apoptosis in a manner refractory to the addition of EGF but inhibition of p38 phosphorylation with its specific inhibitor SB 203580 does not increase apoptosis. EGF also activates sphingosine kinase-1 (SPHK-1), which converts sphingosine to sphingosine-1-phosphate, and its inhibition with dimethyl sphingosine (DMS) increased trophoblast death. Inhibition of SPHK-1 also did not affect EGF stimulated phosphorylation of PI-3 kinase, Akt, ERK1/2 or p38 but inhibition of PI-3 kinase with a specific inhibitor LY294002 partly (40%) inhibited the EGF-stimulated increase in SPHK-1 activity. We conclude that, in addition to the PI-3 kinase and ERK1/2 pathways, EGF acts through its receptor to stimulate JNK, p38 and SPHK-1 pathways, but that the JNK and SPHK-1, and not the p38, pathways are involved in suppressing apoptosis. This information provides evidence that EGF stimulates survival along multiple pathways that differ in trophoblast and other cell types.