Cardiovascular function in 8- to 9-year-old singletons born after ART with frozen and fresh embryo transfer

Comprehensive Health Assessment of School-Age Children Conceived by Assisted Reproductive Technology: A Prospective Cohort Follow-Up Study

OBJECTIVE

To assess the comprehensive health status of school-age children conceived through assisted reproductive technology (ART) compared to that of those conceived naturally.

DESIGN

A prospective cohort study of children conceived through ART.

SETTING

First Affiliated Hospital of Nanjing Medical University, China.

POPULATION SAMPLE

One hundred school-age children were enrolled and followed up (51 conceived via ART and 49 naturally conceived (controls)).

METHODS

A comprehensive health status assessment was performed in children aged 6-12 years, including anthropometric measurements, glucose-lipid metabolism, echocardiography, intelligence, behaviour, vision and hearing. Multivariate regression models were used to adjust for sociodemographic and perinatal covariates.

MAIN OUTCOME MEASURES

Comprehensive health status of children conceived via ART.

RESULTS

Children conceived by ART had similar height, weight, blood pressure, blood glucose and lipid profiles compared to the controls. Echocardiography showed similar cardiac geometric morphology and left/right ventricular diastolic-systolic function between the two groups. ART children had lower carotid intima-media thickness than controls (0.52 ± 0.11 vs. 0.58 ± 0.11). Visual acuity, hearing and intellectual and behavioural assessments were similar. An alternating covering test for the eyes showed a higher incidence of abnormal eye movement in the ART group than in the control group (87.76% vs. 68.89%).

CONCLUSIONS

The similar overall health status of ART- and naturally conceived children is reassuring for those receiving ART. However, our study shows a possible increase in the incidence of latent exotropia among ART children. Long-term follow-up is warranted to assess the overall health status associated with ART throughout the lifespan.

Investigation of cardiac remodeling and cardiac function on fetuses conceived via artificial reproductive technologies: a review

The prevalence of artificial reproductive technologies (ART), such as intra-uterine insemination (IUI), in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI), has surged in response to the global increase in infertility rates, now impacting 17.5 % of couples. With over nine million babies born through ART, the safety and efficacy of these methods are largely recognized; however, emerging concerns regarding their association with prenatal and long-term health risks, especially cardiovascular disease (CVD), necessitate a thorough examination. This review synthesizes recent findings on the cardiac remodeling observed in ART-conceived fetuses, highlighting the potential for sub-clinical dysfunction and subsequent cardiovascular anomalies that may extend into adolescence. It delves into the perinatal complications linked to ART and examines the contribution of the renin-angiotensin system, epigenetic modifications, and altered microRNA expressions to fetal cardiovascular development. The analysis further differentiates the cardiac effects of fresh vs. frozen ART cycles and investigates the enduring nature of these changes beyond birth. Addressing the elevated CVD risk among ART individuals, the review suggests proactive measures, including lifestyle adjustments initiated early in life, to mitigate potential adverse outcomes. It emphasizes the critical need for ongoing research and intervention strategies to safeguard the cardiovascular health of the increasing number of ART-conceived individuals.

Visceral and subcutaneous adipose tissue in children born after ART with frozen and fresh embryo transfers

STUDY QUESTION

Is the ratio of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) comparable between children following ART and natural conception (NC)?

SUMMARY ANSWER

Children conceived by frozen embryo transfer (FET) had slightly lower VAT/SAT ratios than children following NC; no difference in VAT/SAT ratio was observed in children born following fresh embryo transfer (Fresh-ET) as compared to those born from NC.

WHAT IS KNOWN ALREADY

The VAT/SAT ratio is closely related to the metabolic profile, with a high ratio increasing the risk of cardiometabolic diseases. To our knowledge, no studies have reported the VAT/SAT ratio in children following ART.

STUDY DESIGN SIZE DURATION

This prospective exploratory observational cohort study included 150 singletons aged 7-10 years. All children were born in eastern Denmark. The study was conducted between November 2018 and August 2020.

PARTICIPANTS/MATERIALS SETTING METHODS

This is a sub-study of the 'Health in Childhood following Assisted Reproductive Technology' (HiCART) study. The children were conceived after FET (n = 50), Fresh-ET (n = 50), and NC (n = 50), and children conceived by NC were matched to ART children by sex and birth year. The children underwent abdominal MRI for the quantification of abdominal adipose tissues along with measurements of blood pressure, fasting blood samples, anthropometric measurements, and dual-energy X-ray absorptiometry scans. The volumes of VAT and SAT were semi-automatically quantified, blinded for the mode of conception. The level of statistical significance was set to a P-level below 0.05. Multivariable linear regression analysis of the VAT/SAT ratio was performed to adjust for confounders in a five-step approach: Model 1: Adjusted for child age and sex; Model 2: Model 1 plus maternal age at delivery and maternal BMI at pregnancy; Model 3: Model 2 plus birth weight and child BMI; Model 4a: Model 3 plus maternal educational level; Model 4b: Model 3 plus pubertal status. The confounders were selected based on their association with metabolic risk factors according to previous studies.

MAIN RESULTS AND THE ROLE OF CHANCE

As previously reported in the HiCART studies, there were no differences between the groups in anthropometric measurements including BMI, lean body mass, blood pressure, or triglycerides. The crude VAT/SAT ratio differed significantly between the three groups (mean (SD); FET 0.26 (0.08), Fresh-ET 0.29 (0.07), NC 0.30 (0.08), ANOVA-P = 0.014). Pairwise comparison revealed that children conceived after FET had lower crude VAT/SAT ratio than children conceived after NC (P = 0.007) with a mean difference of -0.04, 95% CI (-0.07; -0.01), and a tendency for a lower VAT/SAT ratio as compared to the Fresh-ET group (P = 0.059) with a mean difference of -0.03, 95% CI (-0.06; 0.00). Lower VAT/SAT ratio in FET as compared to NC remained after adjustment for child age and sex (Model 1: -0.04 (-0.07; -0.01)), maternal age at delivery and maternal BMI at pregnancy (Model 2: -0.04 (-0.07; -0.01)), birth weight and child BMI (Model 3: -0.04 (-0.07; -0.01)), maternal educational level (Model 4a: -0.05 (-0.08; -0.01)), and puberty (Model 4b: -0.04 (-0.08; -0.01)) in a five-step approach. Repeated analysis of twenty MRI scans showed good intra-rater repeatability of VAT and SAT volume quantifications.

LIMITATIONS REASONS FOR CAUTION

The sample size was relatively small and selection bias due to differences in intrinsic factors between the three groups may affect the results. Well-described confounders from the literature were included in the multivariable regression analysis, but the observational nature of this cohort study hinders the establishment of causality.

WIDER IMPLICATIONS OF THE FINDINGS

Reassuringly, this study found no clinically important difference in VAT/SAT ratio between children following ART (both FET and Fresh-ET) and NC, although a small but significantly lower VAT/SAT ratio was found in children born after FET compared with NC children.

STUDY FUNDING/COMPETING INTERESTS

A.R.O was supported by a scholarship from Herlev-Gentofte Copenhagen University Hospital. The study was funded by grants from Novo Nordisk Foundation (NNF18OC0034092, NFF19OC0054340) and The Research Foundations at Rigshospitalet and Herlev-Gentofte Copenhagen University Hospital (unrestricted grant). A.P. has received grants (via her institution), honoraria, and consulting fees from Gedeon Richter, Ferring Pharmaceuticals, and Merck A/S, as well as consulting fees from Novo Nordisk A/S and Cryos, honoraria from Organon and support for attending meetings (via her institution) from Gedeon Richter. K.M.M. has received royalties from Gyldendal and consulting fees from The National Board of Wealth and Welfare in Sweden, in addition to honoraria from Novo Nordisk A/S and Lundbeck A/S, and serves as a medical expert for the Ministry of Justice, Department of Civil Affairs. All other authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT03719703.

Blastocyst exposure to plastic during mice in vitro fertilization impacts placental development

INTRODUCTION

Pregnancies from Assisted Reproductive Technologies (ARTs) are associated with a significant prevalence of maternal, neonatal and long-term adverse health issues. These anomalies are generally attributed to the in vitro manipulations involved in these procedures. Concerns have been raised on the quality of the culture media, however the potential influence of the chemical composition of the devices used in the in vitro fertilization (IVF) has been poorly analysed. By comparing the transcriptomes of placentas from mouse blastocysts obtained by IVF on plasticware, glassware and naturally conceived, we have previously established that plasticware profoundly impacts placental development.

METHODS

Transcriptomics, transcriptome deconvolution analysis, Gene Set Enrichment Analysis.

RESULTS

Plasticware alters placental gene expression mostly in the trophoblast compartment, and alters cell composition favouring Glycogen Cells. These modifications correlate with alterations of epigenetic mechanisms (alterations of imprinted genes, microRNAs expression, methylation alterations). Also, sex-stratified analysis reveals that these effects are more drastic in female than male placentas. The effect of glassware on the transcriptome and cellular composition of the placenta is milder, and in particular has lower impact on the imprinted gene or microRNAs expression.

CONCLUSION

In vitro culture in plasticware during IVF procedures sex-specifically alters gene expression and/or cell composition in the placenta, possibly through factors released by the plasticware having an action on epigenetic actors (imprinted genes, miRNAs and DNA methylation).

Infertility treatment and offspring blood pressure-a systematic review and meta-analysis

BACKGROUND

Studies have inconsistently observed that children conceived by IVF or ICSI have higher blood pressure compared to children not conceived by these ARTs.

OBJECTIVE AND RATIONALE

The aim was to perform a systematic review and meta-analysis of blood pressure measures of offspring conceived by ART and those conceived naturally. Resolving the suspicion of ART as a risk factor of higher blood pressure, and therefore of heart disease, has public health and clinical implications.

SEARCH METHODS

A biomedical librarian searched the Embase, PubMed, and Web of Science databases. Searches were limited to records published in English since 1978. Grey literature was searched. Inclusion criteria were humans born via infertility treatment (vs no treatment) who underwent a blood pressure assessment. Exclusion criteria were non-human participants, non-quantitative studies, absence of a control group, and specialty populations (e.g. cancer patients only). Two reviewers independently screened each record's title and abstract and full text using Covidence, extracted data using Excel, and assessed bias using the National Heart, Lung, and Blood Institute's Quality Assessment Tool for cohort studies.

OUTCOMES

Of 5082 records identified, 79 were included in the systematic review and 36 were included in the meta-analysis of systolic blood pressure (SBP) and diastolic blood pressure (DBP) in ART and non-ART groups. Overall, 34 reports including 40 effect sizes from 25 unique cohorts, compared blood pressure between ART (N = 5229) and non-ART (N = 8509, reference) groups with no covariate adjustment. No standardized mean differences (SMD) in SBP (0.06 per SD of mmHg, 95% CI = -0.05, 0.18) or DBP (0.11, 95% CI = -0.04, 0.25) by treatment were found, but the heterogeneity was considerable (I2=76% for SBP and 87% for DBP). Adjusted analyses were presented in 12 reports, representing 28 effect sizes from 21 unique cohorts (N = 2242 treatment vs N = 37 590 non-treatment). Studies adjusted for varied covariates including maternal (e.g. age, education, body mass index, smoking, pregnancy complications), child (e.g. sex, age, physical activity, BMI, height), and birth characteristics (e.g. birth weight and gestational age). Adjusted results similarly showed no SMD for SBP (-0.03, 95% CI = -0.13, 0.08) or DBP (0.02, 95% CI = -0.12, 0.16), though heterogeneity remained high (I2 = 64% and 86%). Funnel plots indicated a slight publication bias, but the trim and fill approach suggested no missing studies. Removal of five studies which adjusted for birth outcomes (potentially over-adjusting for mediators) made no material difference. Type of treatment (e.g. IVF vs ICSI), period effects by birth year (≤2000 vs >2000), offspring age group (<8, 8-14, 15+), or study location (e.g. Europe) did not modify the results.

WIDER IMPLICATIONS

In conclusion, conception by ART was not associated with offspring blood pressure in a meta-analysis, although considerable heterogeneity was observed. Given the increasing number of children born using ART, perpetuating a difference in blood pressure would mean unnecessary risk screening for many children/adults on a population level. At a clinical level, couples considering these reproductive technologies have some reassurance that there is no evidence of strong vascular 'programming' due to the techniques used.

REGISTRATION NUMBER

PROSPERO No. CRD42022374232.

Metabolic profiles of children aged 2-5 years born after frozen and fresh embryo transfer: A Chinese cohort study

BACKGROUND

Frozen embryo transfer (FET) has become a widely employed assisted reproductive technology technique. There have historically been concerns regarding the long-term metabolic safety of FET technology in offspring due to pregnancy-induced hypertension and large for gestational age, both of which are well-recognized factors for metabolic dysfunction of children. Therefore, we aimed to compare the metabolic profiles of children born after frozen versus fresh embryo transfer at 2 to 5 years of age.

METHODS AND FINDINGS

This was a prospective cohort study. Using data from the "Assisted Reproductive Technology borned KIDs (ARTKID)," a birth cohort of offspring born from assisted reproductive technology at the Institute of Women, Children and Reproductive Health, Shandong University, China. We included 4,246 singletons born after FET (n = 2,181) and fresh embryo transfer (n = 2,065) enrolled between 2008 and 2019 and assessed the glucose and lipid variables until the age of 2 to 5 years. During a mean follow-up of 3.6 years, no significant differences were observed in fasting blood glucose, fasting insulin, Homeostatic Model Assessment of Insulin Resistance Index, total cholesterol, triglycerides, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol levels between offspring conceived by fresh and frozen embryo transfer in the crude model and adjusted model (adjusted for parental age, parental body mass index, parental education level, paternal smoking, parity, offspring age and sex). These results remained consistent across subgroup analyses considering offspring age, the stage of embryo transfer, and the mode of fertilization. Results from sensitivity analysis on children matched for age within the cohort remains the same. The main limitation of our study is the young age of the offspring.

CONCLUSIONS

In this study, the impact of FET on glucose and lipid profiles during early childhood was comparable to fresh embryo transfer. Long-term studies are needed to evaluate the metabolic health of offspring born after FET.

Blood pressure and lipid profiles in children born after ART with frozen embryo transfer

STUDY QUESTION

Are blood pressure (BP) and lipid profiles different between children conceived after ART with frozen embryo transfer (FET), fresh embryo transfer (fresh-ET), and natural conception (NC)?

SUMMARY ANSWER

Girls conceived after FET had significantly higher systolic BP and heart rate compared with girls born after fresh-ET; boys conceived after FET had a slightly more favourable lipid profile compared with boys born after fresh-ET and NC.

WHAT IS KNOWN ALREADY

Children conceived after ART with FET are more often born large for gestational age (LGA). LGA in general increases the risk of obesity, diabetes, and cardiovascular disease later in life. Studies on mice and humans on the whole ART population have raised concerns about premature vascular ageing and higher BP. The cardiovascular health of children born after FET is scarcely explored and the results are diverging.

STUDY DESIGN SIZE DURATION

This study was part of the cohort study 'Health in Childhood following Assisted Reproductive Technology' (HiCART), which included 606 singletons (292 boys) born between December 2009 and December 2013: 200 children were conceived after FET; 203 children were conceived after fresh-ET; and 203 children were conceived naturally and matched for birth year and sex. The study period lasted from January 2019 to September 2021.

PARTICIPANTS/MATERIALS SETTING METHODS

The included children were 7-10 years of age at examination and underwent a clinical examination with anthropometric measurements, pubertal staging, and BP measurement. Additionally, a fasting blood sample was collected and analysed for cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL), and triglycerides. Systolic and diastolic BP were converted to standard deviation scores (SDS) using an appropriate reference and accounting for height (SDS) of the child. The three study groups were compared pairwise using a univariate linear regression model. Mean differences were adjusted for confounders using multiple linear regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Girls and boys conceived after FET had significantly higher birthweight (SDS) compared with naturally conceived peers (mean difference: girls: 0.35, 95% CI (0.06-0.64), boys: 0.35, 95% CI (0.03-0.68)). Girls conceived after FET had significantly higher systolic BP (SDS) and heart rate compared with girls conceived after fresh-ET (adjusted mean difference: systolic BP (SDS): 0.25 SDS, 95% CI (0.03-0.47), heart rate: 4.53, 95% CI (0.94-8.13)). Regarding lipid profile, no significant differences were found between the three groups of girls. For the boys, no significant differences were found for BP and heart rate. Lipid profiles were more favourable in boys born after FET compared with both boys conceived after fresh-ET and NC. All outcomes were adjusted for parity, maternal BMI at early pregnancy, smoking during pregnancy, educational level, birthweight, breastfeeding, child age at examination, and onset of puberty.

LIMITATIONS REASONS FOR CAUTION

The participation rate varied from 18 to 42% in the three groups, and therefore selection bias cannot be excluded. However, extensive non-participant analyses were performed that showed almost no differences in background characteristics between participants and non-participants in the three groups, making selection bias less likely.

WIDER IMPLICATIONS OF THE FINDINGS

The higher birthweight in children conceived after FET was associated with increased systolic BP (SDS) and heart rate in girls conceived after FET compared with fresh-ET. This may be an early indicator of compromised long-term cardiovascular health in this group. The study was not powered to investigate these outcomes and further studies are therefore warranted to confirm the findings.

STUDY FUNDING/COMPETING INTERESTS

The study was funded by the Novo Nordisk Foundation (grant number: NNF18OC0034092, NFF19OC0054340) and Rigshospitalets Forskningsfond. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT03719703.

Ultrasound evaluation of the cardiovascular system in offspring conceived through assisted reproductive technology

With the widespread application of assisted reproductive technology, the health issues of offspring conceived through assisted reproductive technology have also received increasing attention. Animal experiments and clinical studies have found subclinical adverse changes in the cardiovascular system of assisted reproductive offspring. Assisted reproductive technology itself may be just one of the many factors contributing to this phenomenon, with epigenetics playing an important role. Ultrasound technology can be used to assess the morphological structure and function of the cardiovascular system in assisted reproductive offspring from the fetal stage, providing the possibility to study the potential cardiovascular damage in this large population. This review aims to explore the effects and mechanisms of assisted reproductive technology on the cardiovascular system of offspring and provide a review of the research progress in ultrasound technology in this area.

Cardiovascular health of offspring conceived by assisted reproduction technology: a comprehensive review

Recently, the use of assisted reproductive technology (ART) has rapidly increased. As a result, an increasing number of people are concerned about the safety of offspring produced through ART. Moreover, emerging evidence suggests an increased risk of cardiovascular disease (CVD) in offspring conceived using ART. In this review, we discuss the epigenetic mechanisms involved in altered DNA methylation, histone modification, and microRNA expression, as well as imprinting disorders. We also summarize studies on cardiovascular changes and other risk factors for cardiovascular disease, such as adverse intrauterine environments, perinatal complications, and altered metabolism following assisted reproductive technology (ART). Finally, we emphasize the epigenetic mechanisms underlying the increased risk of CVD in offspring conceived through ART, which could contribute to the early diagnosis and prevention of CVD in the ART population.

Cardiovascular autonomic nervous function in children conceived by assisted reproductive technology with frozen or fresh embryo transfer

As a result of epigenetic changes, children conceived by assisted reproduction may be at risk of premature cardiovascular aging with notably increased blood pressures. Their cardiovascular autonomic nervous function is unknown. Therefore, this study investigated the cardiovascular autonomic nervous function in 8-12-yr-old children (51% girls) conceived naturally (n = 33) or by assisted reproduction with frozen (n = 34) or fresh (n = 38) embryo transfer by evaluating heart rate variability, during rest; from provocation maneuvers; and from baroreflex function. Heart rate and blood pressure response to provocation maneuvers and baroreflex function were comparable between children conceived naturally or by assisted reproduction. The mean RR-interval and high-frequency component of heart rate variability were lower in children conceived by assisted reproduction than in children conceived naturally. Children conceived by fresh embryo transfer had ∼17% lower heart rate-corrected standard deviation of normal-to-normal R-R intervals; ∼22% lower heart rate-corrected square root of the mean of the squared difference between successive R-R intervals; and ∼37% higher low-frequency/high-frequency ratio than naturally conceived children. Children conceived by assisted reproduction still had lower heart rate variability and vagal modulation than naturally conceived children after adjustment for confounders. Thus, these results raise the possibility of sympathetic predominance in children conceived by assisted reproduction. Therefore, it is important to reproduce these results in larger and older cohorts as sympathetic predominance relates with cardiovascular and metabolic diseases.NEW & NOTEWORTHY We observed that children conceived by assisted reproductive technology (both frozen and fresh embryo transfer) had lowered heart rate variability during rest as compared with children conceived naturally. During physiological stress maneuvers, however, the cardiovascular autonomic nervous regulation was comparable between children conceived by assisted reproductive technologies and naturally. Our findings highlight the potential that lowered heart rate variability during rest in children conceived by assisted reproductive technologies may precede premature hypertension.

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.

Long-term outcomes for children conceived by assisted reproductive technology

Worldwide, more than 10 million children have been born after assisted reproduction technology (ART), comprising up to 7.9% of children born in Europe and up to 5.1 % of children born in the US in 2018. The short-term outcome for children born after ART is well-known from numerous publications, with higher rates of preterm birth and low birth weight in children born after fresh embryo transfer and higher rates of large for gestational age and high birth weight in children born after frozen embryo transfer compared with children born after spontaneous conception. Higher rates of birth defects in children born after ART have also been shown consistently over time. Studies on long-term health outcomes after ART are scarcer but suggest an increased risk of altered blood pressure and cardiovascular function in children born after ART. In this review, we summarize long-term health outcomes in children born after ART and discuss whether the increased health risks are associated with intrinsic maternal or paternal factors related to subfertility or ART treatments per se. Finally, we speculate where the future will bring us regarding ART treatment strategies and the safety of the mother and child.

Fetal cardiac function at midgestation and conception by in-vitro fertilization

OBJECTIVE

To assess differences in cardiac morphology and function at midgestation in fetuses conceived by in-vitro fertilization (IVF), using fresh or frozen embryo transfer, compared with those conceived naturally.

METHODS

This was a prospective study of 5801 women with a singleton pregnancy attending for a routine ultrasound examination at 19 + 0 to 23 + 6 weeks' gestation, including 343 that conceived by IVF. Conventional and more advanced echocardiographic modalities, including speckle-tracking analysis, were used to assess fetal cardiac function in the right and left ventricles. The morphology of the fetal heart was assessed by calculating the right and left sphericity index. Placental perfusion and function were assessed by measurement of uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF), respectively.

RESULTS

Fetuses that were conceived by IVF, compared with those conceived spontaneously, had significantly lower right and left ventricular sphericity index, higher left ventricular global longitudinal strain and lower left ventricular ejection fraction. There were no significant differences in any of the cardiac indices within the IVF group between the fresh and frozen embryo transfers. In the IVF group, compared with spontaneously conceived pregnancies, UtA-PI was lower and PlGF was higher, suggesting better placental perfusion and function.

CONCLUSIONS

Our study demonstrates that, in IVF pregnancies, compared with those conceived spontaneously, there is evidence of fetal cardiac remodeling at midgestation, which is not related to the use of fresh or frozen embryo transfer. In the IVF group, compared with naturally conceived pregnancies, fetal heart was globular and left ventricular systolic function was mildly reduced. Whether these cardiac changes are accentuated later in pregnancy and remain in the postnatal period remains to be established. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Cardiac remodeling from the fetus to adulthood

Prenatal cardiac remodeling refers to in utero changes in the fetal heart that occur as a response to an adverse intrauterine environment. In this article, we will review the main mechanisms leading to cardiac remodeling and dysfunction, summarizing and describing the major pathological conditions that have been reported to be related to this in utero plastic adaptive process. We will also recap the current evidence regarding the persistence of fetal cardiac remodeling and dysfunction, both in infancy and later in adult life. Moreover, we will discuss primary, secondary, and tertiary preventive measures and future clinical and research aspects.

The longer-term effects of IVF on offspring from childhood to adolescence

It is well established that there are increased pregnancy-related complications for a woman who conceives through assisted reproductive treatment (ART). Furthermore, it is known that the risk to the child born is greater, believed to be related to prematurity and growth restriction. Studies have also reported epigenetic changes in the DNA of offspring conceived through ART. In addition, it is believed that they have a greater risk of congenital malformations, although some of these risks may relate to underlying infertility, rather than the ART treatment per se. As a result, it may be expected that there is a greater risk to the longer-term health of the child who is born from ART; however, evidence about the long-term health of children conceived through ART is reassuring. Even though, it is recognised that many of the studies in this field come with limitations. Low numbers of participants is one of the major limitations, which makes subgroup analyses for diverse types of ART, or diverse types of infertility, not feasible. Furthermore, studies are often limited by short follow-up periods because of the difficulty and costs involved in longitudinal study designs. In addition, the rapid changes over time in ART limit the generalisability and significance of long-term findings. Well-designed studies investigating the long-term health outcomes of ART-conceived offspring and the potential influences of various aspects of the ART procedure, as well as studies of the potential underlying epigenetic mechanisms, are imperative. Furthermore, conclusions from childhood hospitalisation data from the United Kingdom, the long-term follow-up and quality of life study from researchers in Melbourne, and the data published from the Western Australian Growing Up Healthy Study will go a long way to help reassure current and prospective parents who may require ART to conceive.

Conception by fertility treatment and cardiometabolic risk in middle childhood

OBJECTIVE

To evaluate whether children conceived using assisted reproductive technology (ART) or ovulation induction (OI) have greater cardiometabolic risk than children conceived without treatment.

DESIGN

Clinical assessments in 2018-2019 in the Upstate KIDS cohort.

SETTING

Clinical sites in New York.

PATIENT(S)

Three hundred thirty-three singletons and 226 twins from 448 families.

INTERVENTION(S)

Mothers reported their use of fertility treatment and its specific type at baseline and approximately 4 months after delivery. High validity of the self-reported use of ART was previously confirmed. The children were followed up from infancy through 8-10 years of age. A subgroup was invited to participate in clinic visits.

MAIN OUTCOME MEASURE(S)

The measurements of blood pressure (BP), arterial stiffness using pulse wave velocity, anthropometric measures, and body fat using bioelectrical impedance analysis were performed (n = 559). The levels of plasma lipids, C-reactive protein, and hemoglobin A1c were measured using blood samples obtained from 263 children.

RESULT(S)

The average age of the children was 9.4 years at the time of the clinic visits Approximately 39% were conceived using fertility treatment (18% using ART and 21% using OI). Singletons conceived using fertility treatment (any type or using ART or OI specifically) did not statistically differ in systolic or diastolic BP, heart rate, or pulse wave velocity. Singletons conceived using OI were smaller than singletons conceived without treatment, but the average body mass index of the latter was higher (z-score: 0.41 [SD, 1.24]) than the national norms. Twins conceived using either treatment had lower BP than twins conceived without treatment. However, twins conceived using OI had significantly higher arterial stiffness (0.59; 95% CI, 0.03-1.15 m/s), which was attenuated after accounting for maternal BP (0.29; 95% CI, -0.03 to 0.46 m/s). Twins did not significantly differ in size or fat measures across the groups. The mode of conception was not associated with the levels of lipids, C-reactive protein, or glycosylated hemoglobin.

CONCLUSION(S)

Clinical measures at the age of 9 years did not indicate greater cardiometabolic risk in children conceived using ART or OI compared with that in children conceived without treatment.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov #NCT03106493.

Aortic distensibility is equal in prepubertal girls and boys and increases with puberty in girls

Windkessel function is governed by conductance artery compliance that is associated with cardiovascular disease in adults independently of other risk factors. Sex-related differences in conductance artery compliance partly explain the sex-related differences in risk of cardiovascular disease. Studies on sex-related differences in conductance artery function in prepubertal children are few and inconclusive. This study determined conductance artery compliance and cardiac function by magnetic resonance imaging in 150 healthy children (75 girls) aged 7-10 years. Any sex-related difference in conductance artery function was determined with correction for other potential predictors in multivariable linear regression models. Our data showed that ascending (crude mean difference 1.11 95% CI (0.22; 2.01)) and descending (crude mean difference 1.10 95% CI (0.09; 1.91)) aortic distensibility were higher in girls, but differences disappeared after adjustment for pubertal status and other identified potential predictors. Systolic and diastolic blood pressure, cardiac output, left ventricle (LV) systolic function, and total peripheral resistance did not differ between the sexes. In girls, heart rate was 7 bpm higher, whereas pulse pressure (by 2 mmHg), and LV end-diastolic volume index (by 7 mL) and stroke volume (by 5 mL) were lower. LV peak filling rate indexed to LV end-diastolic volume was 0.5 s^-1 higher in girls. In conclusion, prepubertal girls and boys have equal conductance artery function. Thus, the well-known sex difference in adult conductance artery function seems to develop after the onset of puberty with girls initially increasing aortic distensibility.

Comparison of the cardiometabolic profiles of adolescents conceived through ART with those of a non-ART cohort

STUDY QUESTION

Is the cardiometabolic health of adolescents conceived through ART worse than that of their counterparts conceived without ART?

SUMMARY ANSWER

The majority of cardiometabolic and vascular health parameters of adolescents conceived through ART are similar or more favourable, than those of their counterparts of similar age and conceived without ART.

WHAT IS KNOWN ALREADY

It has been proposed that the cardiometabolic health of offspring conceived with ART may be unfavourable compared to that of their counterparts conceived without ART. The literature pertaining to cardiometabolic health of offspring conceived after ART is contradictory, but generally suggests unfavourable cardiometabolic health parameters, such as an increase in blood pressure (BP), vascular dysfunction and adiposity, as well as unfavourable glucose and lipid profiles. With over 8 million children and adults born through ART worldwide, it is important to investigate whether these early signs of adverse cardiometabolic differences persist into adolescence and beyond.

STUDY DESIGN, SIZE, DURATION

The Growing Up Healthy Study (GUHS) is a prospective cohort study that recruited 303 adolescents and young adults conceived after ART (aged 13-21 years) and born between 1991 and 2001 in Western Australia. Their health parameters, including cardiometabolic factors, were assessed and compared with counterparts from the Raine Study Generation 2 (Gen2). The 2868 Gen2 participants were born 1989-1992 and are representative of the Western Australian adolescent population. At ∼17 years of age (2013-2017), 163 GUHS participants replicated assessments previously completed by Gen2 at a similar age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cardiometabolic parameters were compared between a total of 163 GUHS and 1457 Gen2 adolescents. Separate male (GUHS n = 81, Gen2 n = 735) and female (GUHS n = 82, Gen2 n = 722) analyses were conducted. Assessments consisted of a detailed questionnaire including health, lifestyle and demographic parameters, anthropometric assessments (height, weight, BMI, waist circumference and skinfold thickness), fasting serum biochemistry, arterial stiffness and BP (assessed using applanation tonometry). Abdominal ultrasonography was used to assess the presence and severity of hepatic steatosis, and thickness of abdominal fat compartments. Non-alcoholic fatty liver disease (NAFLD) was diagnosed if there was sonographic fatty liver in the absence of significant alcohol consumption. Chi2, Fisher's exact and Mann-Whitney U tests, performed in SPSS V25, examined cohort differences and generalized estimating equations adjusted for the following covariates: singleton vs non-singleton pregnancy, birthweight (z-score), gestational age, BMI, smoking, alcohol consumption in the past 6 months and parent cardiovascular status. Arterial stiffness measures and waist circumference were additionally adjusted for height, and female analyses were additionally adjusted for use of oral contraceptives in the preceding 6 months.

MAIN RESULTS AND THE ROLE OF CHANCE

In adjusted analyses, GUHS females had a lower BMI (22.1 vs 23.3 kg/m2, P = 0.014), and thinner skinfolds (triceps, subscapular, mid-abdominal; 16.9 vs 18.7 mm, P = 0.021, 13.4 vs 15.0 mm, P = 0.027, 19.7 vs 23.2 mm, P < 0.001, respectively), whereas males were not significantly different. Waist circumference was lower in GUHS adolescents (males: 78.1 vs 81.3 cm, P = 0.008, females: 76.7 vs 83.3 cm, P = 0.007). There were no significant differences between the two groups in glucose, insulin, homeostatic model assessment for insulin resistance, low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol (non-HDL-C), total cholesterol (TC), alanine aminotransferase and high-sensitivity C-reactive protein in both sexes. In females, serum triglycerides were lower in GUHS adolescents (1.0 vs 1.2 mmol/l, P = 0.029). GUHS males had higher serum HDL-C (1.1 vs 1.0 mmol/l, P = 0.004) and a lower TC/HDL-C ratio (3.2 vs 3.6, P = 0.036). There were no significant differences in the prevalence of NAFLD or steatosis severity scores between the cohorts in males and females. GUHS females had less subcutaneous adipose tissue (9.4 vs 17.9 mm, P < 0.001), whereas GUHS males had greater visceral adipose thickness (44.7 vs 36.3 mm, P < 0.001). There was no significant difference in pre-peritoneal adipose thickness. Pulse wave velocity was lower in GUHS males (5.8 vs 6.3 m/s, P < 0.001) and heart rate corrected augmentation index was lower in GUHS females (-8.4 vs -2.7%, P = 0.048). There were no significant differences in BP or heart rate in males or females between the two groups.

LIMITATIONS, REASONS FOR CAUTION

Despite the substantial study size and the unique study design of the ART cohort, we were unable to differentiate between different types of ART, due to the low number of ICSI cycles (e.g. IVF vs ICSI), draw definite conclusions, or relate the outcomes to the cause of infertility. Considering the differences in time points when both cohorts were studied, external factors could have changed, which could not be accounted for. Given the observational nature of this study, causation cannot be proven.

WIDER IMPLICATIONS OF THE FINDINGS

Contrary to our hypothesis and previous findings focussing mainly on childhood, this study reports mostly similar or favourable cardiometabolic markers in adolescents conceived with ART compared to those conceived without ART. The greater visceral adipose thickness, particularly present in males, requires further investigation. While these findings are generally reassuring, future well-designed and appropriately powered studies are required to definitively address the issue of cardiometabolic health in ART adults.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by NHMRC project grant number 1042269 and R.J.H. received education grant funding support from Ferring Pharmaceuticals. R.J.H. is the Medical Director of Fertility Specialists of Western Australia and a shareholder in Western IVF. He has received educational sponsorship from MSD, Merck-Serono and Ferring Pharmaceuticals. P.B. is the Scientific Director of Concept Fertility Centre, Subiaco, Western Australia. J.L.Y. is the Medical Director of PIVET Medical Centre, Perth, Western Australia.

TRIAL REGISTRATION NUMBER

N/A.