Subfertility versus ART: unraveling the origins of fetal cardiac programming

STUDY QUESTION

Do spontaneously conceived (SC) fetuses from subfertile couples show the same signs of cardiac remodeling as those observed after IVF treatments?

SUMMARY ANSWER

As opposed to fetuses from IVF, SC fetuses from subfertile couples do not show cardiac remodeling and present a similar cardiac structure and function to those of SC fetuses from fertile couples.

WHAT IS KNOWN ALREADY

Subjects conceived by IVF present signs of cardiac remodeling and suboptimal function in utero and during childhood, including larger atria, more globular and thicker ventricles, reduced longitudinal motion, and impaired relaxation as compared to SC individuals from fertile couples. There are no previous publications investigating the independent cardiac programming effects of infertility in SC fetuses from subfertile couples (with time-to-pregnancy (TTP) over 12 months).

STUDY DESIGN, SIZE, DURATION

A prospective cohort study of 289 singleton pregnancies exposed and not exposed to subfertility recruited from 2019 to 2021, including 96 SC pregnancies from fertile couples (TTP under 12 months), 97 SC from subfertile couples (TTP over 12 months), and 96 from IVF after fresh embryo transfer. Fetal echocardiography was performed in all pregnancies. Epidemiological data and perinatal outcomes were collected in all pregnancies. The overall attrition rate was 15.7%.

PARTICIPANTS/MATERIALS, SETTING, METHODS

SC from subfertile couples and IVF pregnancies were identified as eligible at pregnancy diagnosis, and eligible SC pregnancies from fertile couples who attended our maternal-fetal unit were invited to participate at third trimester, being matched to the other groups by maternal age. Fetal echocardiography was performed at 29-34 weeks of pregnancy to assess cardiac structure and function, and results were adjusted by parental age, maternal smoking status, child's birth order, birthweight centile, gestational age, and estimated fetal weight at scan.

MAIN RESULTS AND THE ROLE OF CHANCE

Parental age, ethnicity, BMI, and smoking exposure, median gestational age and estimated fetal weight were similar in all study groups. There were no significant differences in infertility duration or etiology between the subfertile and the IVF populations (TTP: subfertile median 35 months (interquartile range 20-48) versus IVF: 47 (25-61); P-value = 0.051). While both fertile and subfertile SC groups presented similar fetal cardiac results, IVF fetuses showed larger atria (right atria-to-heart ratio: IVF mean 18.9% (SD 3.4) versus subfertile 17.8% (3.5) versus fertile 17.6% (3.3); adjusted P-value < 0.001), more globular ventricles (right ventricular sphericity index: IVF 1.56 (0.25) versus subfertile 1.72 (0.26) versus fertile 1.72 (0.26); <0.001), and thicker myocardial walls (relative wall thickness: IVF 0.86 (0.22) versus subfertile 0.64 (0.13) versus fertile 0.64 (0.18); <0.001). Whereas SC fetuses from fertile and subfertile couples had preserved cardiac function, IVF fetuses showed signs of suboptimal systolic and diastolic function, with reduced tricuspid ring displacement (IVF 7.26 mm (1.07) versus subfertile 8.04 mm (1.18) versus fertile 7.89 mm (1.51); <0.001) and increased left myocardial performance index (IVF 0.49 (0.08) versus subfertile 0.45 (0.09) versus fertile 0.45 (0.10); <0.001). A sub-analysis including only unexplained infertility cases in subfertile SC and IVF groups showed similar results.

LIMITATIONS, REASONS FOR CAUTION

The fetal cardiac changes reported here are subclinical, and most of the cardiovascular parameters were within normal ranges. Although echocardiographic changes are recognized as potential cardiovascular risk factors, their association with long-term cardiovascular disease remains to be demonstrated.

WIDER IMPLICATIONS OF THE FINDINGS

Subfertility per se does not seem to be associated to fetal cardiac remodeling, which has been previously described in IVF fetuses. Future studies are warranted to further investigate other factors related to the observed fetal cardiac changes associated with ART.

STUDY FUNDING/COMPETING INTEREST(S)

This project has been partially funded with support from the Erasmus + Programme of the European Union (Framework Agreement number: 2013-0040). This publication reflects the views only of the author, and the Commission cannot be held responsible for any use, which may be made of the information contained therein. Additionally, the research leading to these results has received funding from 'la Caixa' Foundation under grant agreement LCF/PR/GN18/10310003, the Instituto de Salud Carlos III (PI15/00130, PI16/00861, PI17/00675, PI18/00073, INT21/00027)-co-funded by the European Union, Cerebra Foundation for the Brain Injured Child (Carmarthen, Wales, UK) and AGAUR 2017 SGR grant no 1531. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

P-771 Subfertility versus in vitro fertilization procedures: unravelling the origins of fetal cardiac remodeling in assisted reproductive technologies

Study question

Do spontaneously conceived (SC) fetuses from subfertile couples present signs of cardiac remodeling as those observed after in vitro fertilization (IVF) treatments?

Summary answer

SC fetuses from subfertile couples do not associate cardiac remodeling, and their cardiac structure and function are similar to those of SC from fertile couples.

What is known already

Fetuses and children from IVF associate cardiac remodeling and suboptimal function, including dilated atria, more globular and thicker ventricles, reduced longitudinal motion and impaired relaxationin uteroand after birth. Fetal cardiac changes have been demonstrated both after fresh and frozen embryo transfer. The SC fetuses used as ‘controls’ in our previous publications were conceived by fertile couples thus making it difficult to separate the contribution of infertilityper sefrom the IVF procedures on cardiac programming. There are no previous cardiovascular studies investigating the independent effects of infertility in SC fetuses from subfertile couples (time-to-pregnancy (TTP) over 12 months).

Study design, size, duration

Prospective cohort study of 289 singleton pregnancies recruited from 2017 to 2021, including 96 SC pregnancies from fertile couples (TTP less than 12 months), 97 SC from subfertile couples (TTP over 12 months) and 96 from IVF after fresh ET. Fetal echocardiography was performed in all pregnancies. Epidemiological data and perinatal outcomes were collected in all pregnancies.

Participants/materials, setting, methods

IVF pregnancies from our centre were identified as eligible at pregnancy diagnosis. Eligible SC pregnancies from fertile and subfertile couples who attended our Maternal-Fetal Unit were invited to participate at third trimester, being matched to the IVF pregnancies by maternal age. Fetal echocardiography was performed at 29-34 weeks of pregnancy to assess cardiac structure and function. Echocardiographic comparisons were adjusted by nulliparity, birthweight centile, gestational age and estimated fetal weight at scan.

Main results and the role of chance

Parental age, ethnicity, body mass index and smoking exposure, median gestational age and estimated fetal weight were similar in all study groups. There were no significant differences in infertility duration or aetiology between the subfertile and the IVF populations (TTP: subfertile median 30 months [IQR 20-54] versus IVF: 47 [25-61]; p-value=0.052). While both fertile and subfertile SC groups presented similar fetal cardiac results, IVF fetuses showed larger atria (right atria-to-heart ratio: IVF mean 18.9% [SD 3.4] versus subfertile 17.8% [3.5] versus fertile 17.6% [3.3]; adjusted P-value&lt;0.001), more globular ventricles (right ventricular sphericity index: IVF 1.56 [0.25] versus subfertile 1.72 [0.26] versus fertile 1.72 [0.26]; &lt;0.001), and thicker myocardial walls (relative wall thickness: IVF 0.86 [0.22] versus subfertile 0.64 [0.13] versus fertile 0.64 [0.18]; &lt;0.001). Whereas SC fetuses from fertile and subfertile couples had preserved cardiac function, IVF fetuses showed signs of suboptimal systolic and diastolic function with reduced tricuspid ring displacement (IVF 7.26 mm [1.07] versus subfertile 8.04 mm [1.18] versus fertile 7.89 mm [1.51]; &lt;0.001) and increased left myocardial performance index (IVF 0.49 [0.08] versus subfertile 0.45 [0.09] versus fertile 0.45 [0.10]; &lt;0.001). A sub-analysis including only unexplained infertility cases in subfertile SC and IVF groups showed similar results.

Limitations, reasons for caution

The fetal cardiac changes reported here are subclinical, with most cardiovascular parameters lying within normal ranges. Although echocardiographic changes are recognized as potential cardiovascular risk factors, their association with long-term cardiovascular disease remains to be proven.

Wider implications of the findings

Subfertility per se does not seem to be associated to fetal cardiac remodeling, which have been previously described in IVF fetuses. Future studies are warranted to further investigate the factors related to fetal cardiac changes associated to ART.

Trial registration number

Not a trial

Reference ranges for fetal cardiac, ventricular and atrial relative size, sphericity, ventricular dominance, wall asymmetry and relative wall thickness from 18 to 41 gestational weeks

OBJECTIVE

To construct nomograms for fetal cardiac, ventricular and atrial relative size and geometry parameters from 18 to 41 weeks' gestation using a low-risk population of singleton pregnancies.

METHODS

This was a prospective cohort study of 602 low-risk singleton pregnancies undergoing comprehensive fetal echocardiography, from 18 to 41 weeks of gestation, to assess fetal cardiac, atrial and ventricular relative size and sphericity, ventricular dominance, wall asymmetry and relative wall thickness. Intra- and interobserver measurement reproducibility was evaluated using intraclass correlation coefficients (ICC). In order to construct reference ranges across pregnancy, parametric regressions were tested to model each measurement against gestational age and estimated fetal weight. The measurements evaluated were: cardiothoracic ratio; atrial-to-heart area ratios; ventricular-to-heart area ratios; cardiac, ventricular and atrial sphericity indices; right-to-left basal and midventricular ratios; septal-to-free wall thickness ratios; and relative wall thickness.

RESULTS

Fetal cardiac, ventricular and atrial morphometry for assessing relative size and geometry could be successfully performed in > 95% of the population, with moderate-to-excellent interobserver reproducibility (ICC, 0.623-0.907) and good-to-excellent intraobserver reproducibility (ICC, 0.787-0.938). Cardiothoracic ratio and ventricular right-to-left ratio showed a modest increase throughout gestation. Atrial-to-heart and ventricular-to-heart area ratios, atrial sphericity indices and septal-to-free wall thickness ratios were constant with gestational age. Left and right ventricular basal sphericity indices showed a tendency to decrease at the end of gestation, while left and right midventricular sphericity indices tended to decrease in the second trimester. The cardiac sphericity index and left and right relative wall thickness showed a modest decrease with gestational age. Nomograms across gestation were constructed for all echocardiographic parameters described.

CONCLUSIONS

The assessment of cardiac, ventricular and atrial relative size and geometry is feasible and reproducible in the fetus. We provide standardized reference ranges for these parameters throughout gestation, enabling the accurate assessment of cardiac remodeling patterns during fetal life. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Cardiac remodeling in fetuses conceived by ARTs: fresh versus frozen embryo transfer

STUDY QUESTION

Do fetuses from frozen embryo transfer (FET) present signs of cardiac remodeling and suboptimal function similar to those observed in fetuses from fresh embryo transfer (ET)?

SUMMARY ANSWER

Fetuses from both fresh ET and FET present signs of fetal cardiac remodeling and suboptimal function, with more pronounced changes after fresh ET as compared to FET.

WHAT IS KNOWN ALREADY

Our group and others have previously demonstrated that fetuses and children conceived by ARTs present cardiac remodeling and suboptimal function. These fetuses show dilated atria, more globular and thicker ventricles, reduced longitudinal motion, and impaired relaxation. Cardiac changes were already present in utero and persisted after birth. Most of the ART fetuses included in previous publications were from fresh ET. However, singletons from FET have different perinatal outcomes compared to those from fresh ET. There are no previous studies comparing cardiac morphology and function between fetuses following fresh and FET.

STUDY DESIGN, SIZE, DURATION

This is a prospective cohort study of 300 singleton pregnancies recruited from 2017 to 2020, including 100 spontaneously conceived (SC) pregnancies, 100 fetuses conceived by IVF with FET, and 100 fetuses conceived by IVF with fresh ET. Fetal structural and functional echocardiography was performed in all pregnancies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Pregnancies conceived by IVF were recruited from a single assisted reproduction center, ensuring homogeneity in IVF stimulation protocols, endometrial preparation for FET, laboratory procedures, and embryo culture conditions. SC pregnancies from fertile couples were selected from the general population and matched to IVF pregnancies by maternal age. Epidemiological and perinatal outcomes were collected in all cases. Fetal echocardiography was performed at 28-33 weeks of pregnancy to assess cardiac structure and function in all pregnancies. All echocardiographic comparisons were adjusted by maternal age, nulliparity, birthweight centile, preeclampsia, and prematurity.

MAIN RESULTS AND THE ROLE OF CHANCE

Parental age, ethnicity, body mass index and smoking were similar among the study groups. Median gestational age at echocardiography and estimated fetal weight were similar in all study groups. Both fresh ET and FET groups showed similar fetal echocardiographic changes, with more pronounced features in the fresh ET as compared to FET pregnancies. Fetuses conceived by IVF showed larger atria (right atria-to-heart ratio: fresh ET mean 18.1% (SD 3.2) vs FET 18.0% (3.9) vs SC 17.3% (3.2); linear tendency P-value <0.001), more globular ventricles (right ventricular sphericity index: fresh ET 1.62 (0.29) vs FET 1.61 (0.25) vs SC 1.68 (0.26); <0.001) and thicker myocardial walls (relative wall thickness: fresh ET 0.79 (0.21) vs FET 0.74 (0.22) vs SC 0.65 (0.25); <0.001) as compared to SC pregnancies. Both fresh ET and FET groups also had signs of suboptimal systolic and diastolic function, with reduced tricuspid annular systolic peak velocity (fresh ET 7.17 cm/s (1.22) vs FET 7.41 cm/s (1.19) vs SC 7.58 cm/s (1.32); <0.001) and increased left myocardial performance index (fresh ET 0.53 (0.08) vs FET 0.53 (0.08) vs SC 0.50 (0.09); <0.001) as compared to SC pregnancies.

LIMITATIONS, REASONS FOR CAUTION

The cardiac changes reported here are subclinical, with most cardiovascular indexes lying within normal ranges. Although echocardiographic changes are recognized as potential cardiovascular risk factors, their association with the long-term cardiovascular disease remains to be proven. The observed milder fetal cardiac features in FET fetuses cannot condition the choice of this technique and must be considered together with the global perinatal results related to these gestations.

WIDER IMPLICATIONS OF THE FINDINGS

The identification of cardiac remodeling in fetuses conceived by IVF with fresh ET and FET represents an opportunity for early detection. Future studies are warranted to study the potential long-term consequences of these findings.

STUDY FUNDING/COMPETING INTEREST(S)

This project has been partially funded with support from the Erasmus + Programme of the European Union (Framework Agreement number: 2013-0040). This publication reflects the views only of the author, and the Commission cannot be held responsible for any use, which may be made of the information contained therein. Additionally, the research leading to these results has received funding from 'la Caixa' Foundation under grant agreement LCF/PR/GN18/10310003, the Instituto de Salud Carlos III (PI15/00130, PI17/00675, PI18/00073) integrated into the Plan Nacional de I + D+I and cofinanced by ISCIII-Subdirección General de Evaluación and Fondo Europeo de Desarrollo Regional (FEDER) 'Una manera de hacer Europa', Cerebra Foundation for the Brain Injured Child (Carmarthen, Wales, UK) and AGAUR 2017 SGR grant n° 1531. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Fetal cardiac filling and ejection time fractions by pulsed-wave Doppler: reference ranges and potential clinical application

OBJECTIVES

Fetal cardiac function can be evaluated using a variety of parameters. Among these, cardiac cycle time-related parameters, such as filling time fraction (FTF) and ejection time fraction (ETF), are promising but rarely studied. We aimed to report the feasibility and reproducibility of fetal FTF and ETF measurements using pulsed-wave Doppler, to provide reference ranges for fetal FTF and ETF, after evaluating their relationship with heart rate (HR), gestational age (GA) and estimated fetal weight (EFW), and to evaluate their potential clinical utility in selected fetal conditions.

METHODS

This study included a low-risk prospective cohort of singleton pregnancies and a high-risk population of fetuses with severe twin-twin transfusion syndrome (TTTS), aortic stenosis (AoS) or aortic coarctation (CoA), from 18 to 41 weeks' gestation. Left ventricular (LV) and right ventricular inflow and outflow pulsed-wave Doppler signals were analyzed, using valve clicks as landmarks. FTF was calculated as: (filling time/cycle time) × 100. ETF was calculated as: (ejection time/cycle time) × 100. Intraclass correlation coefficients (ICC) were used to evaluate the intra- and interobserver reproducibility of FTF and ETF measurements in low-risk fetuses. The relationships of FTF and ETF with HR, GA and EFW were evaluated using multivariate regression analysis. Reference ranges for FTF and ETF were then constructed using the low-risk population. Z-scores of FTF and ETF in the high-risk fetuses were calculated and analyzed.

RESULTS

In total, 602 low-risk singleton pregnancies and 54 high-risk fetuses (nine pairs of monochorionic twins with severe TTTS, 16 fetuses with AoS and 20 fetuses with CoA) were included. Adequate Doppler traces for FTF and ETF could be obtained in 95% of low-risk cases. Intraobserver reproducibility was good to excellent (ICC, 0.831-0.905) and interobserver reproducibility was good (ICC, 0.801-0.837) for measurements of all timing parameters analyzed. Multivariate analysis of FTF and ETF in relation to HR, GA and EFW in low-risk fetuses identified HR as the only variable predictive of FTF, while ETF was dependent on both HR and GA. FTF increased with decreasing HR in low-risk fetuses, while ETF showed the opposite behavior, decreasing with decreasing HR. Most recipient twins with severe TTTS showed reduced FTF and preserved ETF. AoS was associated with decreased FTF and increased ETF in the LV, with seemingly different patterns associated with univentricular vs biventricular postnatal outcome. The majority of fetuses with CoA had FTF and ETF within the normal range in both ventricles.

CONCLUSIONS

Measurement of FTF and ETF using pulsed-wave Doppler is feasible and reproducible in the fetus. The presented reference ranges account for associations of FTF with HR and of ETF with HR and GA. These time fractions are potentially useful for clinical monitoring of cardiac function in severe TTTS, AoS and other fetal conditions overloading the heart. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal cardiac remodeling in twin pregnancy conceived by assisted reproductive technology

OBJECTIVE

Recent data suggest that singleton fetuses conceived by assisted reproductive technology (ART) present cardiovascular remodeling that may persist postnatally. Twin pregnancies are more frequent in the ART population and are associated with increased adverse perinatal outcomes, such as hypertensive disorders, gestational diabetes and preterm birth. However, it is unknown whether cardiac remodeling is also present in twin pregnancies conceived by ART. Our aim was to assess the presence of fetal cardiac remodeling and dysfunction in twin pregnancies conceived by ART as compared with those conceived spontaneously (SC).

METHODS

This was a prospective cohort study including 50 dichorionic twin fetuses conceived by ART and 50 SC twin fetuses. The study protocol included collection of baseline/perinatal data and a fetal ultrasound examination at 28-30 weeks' gestation, including assessment of estimated fetal weight, fetoplacental Doppler and fetal echocardiography. Measurements of atrial area, atrial/heart ratio, ventricular sphericity index, free wall thickness, mitral and tricuspid annular plane systolic excursions, and systolic and early diastolic peak velocities were assessed. Multilevel analyses were used to compare perinatal and ultrasonographic parameters. Comparisons of echocardiographic variables were adjusted for parental age, paternal body mass index and incidence of pre-eclampsia.

RESULTS

Compared with SC twins, ART twin fetuses showed significant cardiac changes, predominantly affecting the right heart, such as dilated atria (right atrial/heart area: 15.7 ± 3.1 vs 18.4 ± 3.2, P < 0.001), more globular ventricles (right ventricular sphericity index: 1.57 ± 0.25 vs 1.41 ± 0.23, P = 0.001) and thicker myocardial walls (septal wall thickness: 2.57 ± 0.45 mm vs 2.84 ± 0.41 mm, P = 0.034) together with reduced longitudinal motion (tricuspid annular plane systolic excursion: 6.36 ± 0.89 mm vs 5.18 ± 0.93 mm, P < 0.001).

CONCLUSIONS

ART twin fetuses present signs of cardiac remodeling and dysfunction. These changes are similar to those observed in ART singletons and reinforce the concept of fetal cardiac programing in ART. These results open opportunities for early detection and intervention in infants conceived by ART. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Differential effect of assisted reproductive technology and small-for-gestational age on fetal cardiac remodeling

OBJECTIVE

Fetuses conceived by assisted reproductive technology (ART) and those that are small-for-gestational age (SGA) show cardiovascular remodeling in utero; however, these two conditions are often associated. We aimed to evaluate the differential effect of ART and SGA on fetal cardiac remodeling.

METHODS

This was a prospective cohort study of term singleton pregnancies seen at our department between April 2011 and September 2013. The cohort was divided according to fetal growth and mode of conception into the following four groups: 102 appropriate-for-gestational-age (AGA) fetuses conceived spontaneously (controls), 72 AGA fetuses conceived by ART (ART-AGA), 31 SGA fetuses conceived by ART (ART-SGA) and 28 SGA fetuses conceived naturally (Spont-SGA). SGA was defined as birth weight < 10^th centile. Fetal echocardiography was performed at 28-32 weeks to assess cardiac dimensions, geometry and function.

RESULTS

ART fetuses had dilated atria (mean left atrium-to-heart area ratio: controls, 15 ± 2.7%; ART-AGA, 18 ± 4.1%; Spont-SGA, 14 ± 3.7%) and more globular ventricles (left ventricular sphericity index: controls, 1.77 ± 0.2; ART-AGA, 1.68 ± 0.2; Spont-SGA, 1.72 ± 0.2), with normally sized hearts. In contrast, SGA fetuses had enlarged hearts (cardiothoracic ratio: controls, 24 ± 3%; ART-AGA, 24 ± 4%; Spont-SGA, 29 ± 6%), preserved atrial size, more globular and concentric hypertrophic ventricles (left ventricle relative wall thickness: controls, 0.48 ± 0.17; ART-AGA, 0.54 ± 0.13; Spont-SGA, 0.63 ± 0.23). Both ART and SGA fetuses had decreased longitudinal motion (tricuspid annular ring displacement: controls, 6.5 ± 0.8 mm; ART-AGA, 5.5 ± 0.7 mm; Spont-SGA, 5.9 ± 0.6 mm) and impaired relaxation (left isovolumetric relaxation time: controls, 47.0 ± 7.3 ms; ART-AGA, 50.0 ± 7.9 ms; Spont-SGA, 49.5 ± 9.3 ms). ART-SGA fetuses presented a combination of features from both ART and SGA groups.

CONCLUSION

SGA and conception with ART were associated with distinct patterns of fetal cardiac remodeling, supporting the concept that they are independent causes of cardiac programming. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.