Epigenetic changes and assisted reproductive technologies

DNA methylation in newborns conceived by assisted reproductive technology

Assisted reproductive technology (ART) may affect fetal development through epigenetic mechanisms as the timing of ART procedures coincides with the extensive epigenetic remodeling occurring between fertilization and embryo implantation. However, it is unknown to what extent ART procedures alter the fetal epigenome. Underlying parental characteristics and subfertility may also play a role. Here we identify differences in cord blood DNA methylation, measured using the Illumina EPIC platform, between 962 ART conceived and 983 naturally conceived singleton newborns. We show that ART conceived newborns display widespread differences in DNA methylation, and overall less methylation across the genome. There were 607 genome-wide differentially methylated CpGs. We find differences in 176 known genes, including genes related to growth, neurodevelopment, and other health outcomes that have been associated with ART. Both fresh and frozen embryo transfer show DNA methylation differences. Associations persist after controlling for parents' DNA methylation, and are not explained by parental subfertility.

Bioethics in human embryology: the double-edged sword of embryo research

There has been a significant increase in the use of assisted reproductive therapies (ARTs) over the past several decades, allowing many couples with infertility to conceive. Despite the achievements in this field, a mounting body of evidence concerning the epigenetic risks associated with ART interventions such as ovarian hormonal stimulation, intracytoplasmic sperm injection (ICSI), and in vitro culture (IVC) of oocytes and embryos has also emerged. Induced development of multiple follicles, the IVC media itself, and extended culture may alter the epigenome of both gametes and embryos, resulting in yet to be fully understood developmental, postnatal, and adult life health consequences. Investigators have attempted to decipher the molecular mechanisms mediating ART-induced epigenetic changes using either human samples or animal models with some success. As research in this field continues to expand, the ethical responsibilities of embryologists and researchers have become critically important. Here, we briefly discuss the ethical aspects of ART research, concentrating on the constraints arising from the perceived 'unnaturalness' of many of these procedures. Secondly, we focus on the bioethics and morality of human embryo research in general and how ethically acceptable model systems may be used to mimic early human embryogenesis. Lastly, we review the 14-day culture limit of human embryos and the notion that this rule could be considered of taken into account using new technologies and cues from animal models. The 'black box' of early post-implantation embryogenesis might be revealed using embryo models. As long as this distinct moral line has been drawn and closely followed, we should not fear scientific growth in embryo research. Although in vitro fertilization (IVF) is ethically acceptable, research with human embryos to improve its success raises serious ethical concerns that are in need of constant revisiting.Glossary index: Moral status: the ascription of obligations and rights to embryos on the basis of sentience; Sentience: the capacity of the developing embryo to experience feelings and sensations, such as the awareness of pain; Ectogenesis: the growth of the embryo in an artificial environment outside the mother's body.

Lack of GNAS Remethylation During Oogenesis May Be a Cause of Sporadic Pseudohypoparathyroidism Type Ib

CONTEXT

Pseudohypoparathyroidism type Ib (PHP1B) is characterized by hypocalcemia and hyperphosphatemia due to parathyroid hormone resistance in the proximal renal tubules. Maternal pathogenic STX16/GNAS variants leading to maternal epigenetic GNAS changes impair expression of the stimulatory G protein alpha-subunit (Gsα) thereby causing autosomal dominant PHP1B. In contrast, genetic defects responsible for sporadic PHP1B (sporPHP1B) remain mostly unknown.

OBJECTIVE

Determine whether PHP1B encountered after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) causes GNAS remethylation defects similar to those in sporPHP1B.

DESIGN

Retrospective analysis.

RESULTS

Nine among 36 sporPHP1B patients investigated since 2000, all with loss of methylation (LOM) at the 3 maternal GNAS differentially methylated regions (DMRs) and gain of methylation at the paternal NESP DMR, had been conceived through IVF or ICSI. Besides abnormal GNAS methylation, IVF/ICSI PHP1B cases revealed no additional imprinting defects. Three of these PHP1B patients have dizygotic twins, and 4 have IVF/ICSI-conceived siblings, all with normal GNAS methylation; 2 unaffected younger siblings were conceived naturally.

CONCLUSION

Sporadic and IVF/ICSI-conceived PHP1B patients revealed indistinguishable epigenetic changes at all 4 GNAS DMRs, thus suggesting a similar underlying disease mechanism. Given that remethylation at the 3 maternal DMRs occurs during oogenesis, male factors are unlikely to cause LOM postfertilization. Instead, at least some of the sporPHP1B variants could be caused by a defect or defects in an oocyte-expressed gene that is required for fertility and for re-establishing maternal GNAS methylation imprints. It remains uncertain, however, whether the lack of GNAS remethylation alone and the resulting reduction in Gsα expression is sufficient to impair oocyte maturation.

From lessons on the long-term effects of the preimplantation environment on later health to a "modified ART-DOHaD" animal model

Background

At its earliest stages, mammalian embryonic development is apparently simple but vulnerable. The environment during the preimplantation period, which only lasts a couple of days, has been implicated in adult health, extending to such early stages the concept of the developmental origin of health and disease (DOHaD).

Methods

In this review, we first provide a brief history of assisted reproductive technology (ART) focusing on in vitro culture and its outcomes during subsequent development mainly in mice and humans. Further, we introduce the "MEM mouse," a novel type 2 diabetes mouse model generated by in vitro culture of preimplantation embryos in alpha minimum essential medium (αMEM).

Main findings

The association between ART and its long-term effects has been carefully examined for its application in human infertility treatment. The "MEM mouse" develops steatohepatitis and kidney disease with diabetes into adulthood.

Conclusion

The close association between the environment of preimplantation and health in postnatal life is being clarified. The approach by which severe mouse phenotypes are successfully induced by manipulating the environment of preimplantation embryos could provide new chronic disease animal models, which we call "modified ART-DOHaD" animal models. This will also offer insights into the mechanisms underlying their long-term effects.

Epigenetic Modifications, A New Approach to Male Infertility Etiology: A Review

Recent studies have indicated that epigenetic alterations are critical for normal function and development of spermatozoa during the fertilization process. This review will focus on the latest advances in epigenome profiling of the chromatin modifications during sperm development, as well as the potential roles of epigenetic mechanisms in the context of male infertility. In this review, all data were collected from published studies that considered the effect of epigenetic abnormalities on human spermatogenesis, sperm parameters quality, fertilization process, embryo development and live births. The database PubMed was searched for all experimental and clinical studies using the Keywords "epigenetic modifications", "male infertility", "spermatogenesis", "embryo development" and "reproductive function". Post-translational modifications of histone, DNA methylations and chromatin remodeling are among the most common forms of epigenetic modifications that regulate all stages of spermatogenesis and fertilization process. Incorrect epigenetic modifications of certain genes involved in the spermatogenesis and sperm maturation may be a main reason of male reproductive disorder and infertility. Most importantly, abnormal patterns of epigenetic modifications or transgenerational phenotypes and miRNAs expression may be transmitted from one generation to the next through assisted reproductive techniques (ART) and cause an increased risk of birth defects, infertility and congenital anomalies in children. Epigenetic modifications must be considered as a one of the main factors of unexplained male infertility etiology. Due to high risk of transmitting incorrect primary imprints to offspring, there is a need for more research into epigenetic alterations in couples who benefit of ART support.

Protective placental inflammatory and oxidative stress responses are attenuated in the context of twin pregnancy and chorioamnionitis in assisted reproduction

PURPOSE

Assisted reproduction technologies (ART) are associated with increased risks of pregnancy complications and obstetric interventions. Here, we aimed to determine if ART affects placental inflammation and oxidative stress as a mechanism for unfavorable pregnancy outcomes.

METHODS

The levels of six cytokines (IFN-γ, IL-1β, IL-6, IL-8, IL-10, TNFα) were measured using multiplex ELISA. The activity of four antioxidant enzymes (glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase, superoxide dismutase) and levels of two antioxidants (GSH, vitamin E) were measured using commercial/in-house assays. Markers were compared between ART and unassisted pregnancies, and then groups were stratified using ICD9/10 codes to determine differences in specific clinical contexts.

RESULTS

In unassisted twin pregnancies, there was a trend of decreased cytokine levels (IL-1β, IL-6, IL-8, TNFα, p < 0.05), but cytokines in ART twins were the same or higher. Additionally, GST and GPx activities were lower in unassisted twins, and vitamin E levels were higher in ART twins (p < 0.05). In pregnancies complicated by chorioamnionitis, there was a trend of increased cytokine levels in unassisted pregnancies (IL-1β, IL-6, and IL-8, p < 0.05). No increase was observed in ART, and IFN-γ and TNFα were decreased (p < 0.05). Placental GST and GPx activities were higher in unassisted pregnancies with chorioamnionitis compared to ART (p < 0.05).

CONCLUSION

Attenuation of protective placental inflammatory and oxidative stress responses may play a role in the underlying pathogenesis of negative birth outcomes in ART, expanding our understanding of adverse pregnancy outcomes when ART is used to conceive.

Association of paternal MTHFR polymorphisms (C677T) with clinical outcomes in ICSI treatment

PURPOSE

This study aims to investigate the association between paternal methylenetetrahydrofolate reductase (MTHFR) polymorphisms (C677T) and embryonic development, pregnancy, and neonatal outcomes in intracytoplasmic sperm injection (ICSI) treatment.

METHODS

A total of 191 infertile men undergoing ICSI treatment at the Reproductive and Genetic Hospital, The First Affiliated Hospital of USTC, were recruited between January 2020 and June 2021. The MTHFR C677T polymorphism genotyping was evaluated in these male patients, and they were stratified into three groups according to genotyping results: Control (CC), heterozygote mutated (CT), and mutated homozygote (TT). In addition, we conducted a comparative analysis of embryonic development, pregnancy, and neonatal outcomes among these three groups.

RESULTS

The embryonic development (including normal fertilization rate (80.14% vs. 83.06% vs. 85.10%; p = 0.37), high-quality embryo rate (45.26% vs. 43.69% vs. 46.04%; p = 0.72), blastocyst formation rate (42.47% vs. 43.18% vs. 39.38%; p = 0.62), implantation rate (42.47% vs. 36.25% vs. 41.22%; p = 0.62), and clinical pregnancy rate (64.71% vs. 58.75% vs. 66.67%; p = 0.59) were not comparable among these three groups. Moreover, no significant difference was observed in terms of pregnancy outcomes (including miscarriage rate (24.24% vs. 12.77% vs. 22.5%; p = 0.35) and live birth rate (49.02% vs. 51.25% vs. 51.66%; p = 0.96)). Additionally, no marked difference was observed in terms of neonatal outcome (including, preterm delivery rate (24% vs. 14.63% vs. 9.67%; p = 0.35), birth height (p = 0.75), birth weight (p = 0.35), neonatal sex (p = 0.48), gestational age at delivery (p = 0.24), Apgar score (p = 0.34), and birth defects (0% vs. 2% vs. 9%; p = 0.23) among the study groups.

CONCLUSION

The paternal MTHFR C677T polymorphism is not associated with embryo quality, pregnancy, or neonatal outcomes in ICSI treatment. Therefore, in our population, MTHFR polymorphisms do not provide helpful information in explaining ICSI failure.

Epigenetics in the Uterine Environment: How Maternal Diet and ART May Influence the Epigenome in the Offspring with Long-Term Health Consequences

The societal burden of non-communicable disease is closely linked with environmental exposures and lifestyle behaviours, including the adherence to a poor maternal diet from the earliest preimplantation period of the life course onwards. Epigenetic variations caused by a compromised maternal nutritional status can affect embryonic development. This review summarises the main epigenetic modifications in mammals, especially DNA methylation, histone modifications, and ncRNA. These epigenetic changes can compromise the health of the offspring later in life. We discuss different types of nutritional stressors in human and animal models, such as maternal undernutrition, seasonal diets, low-protein diet, high-fat diet, and synthetic folic acid supplement use, and how these nutritional exposures epigenetically affect target genes and their outcomes. In addition, we review the concept of thrifty genes during the preimplantation period, and some examples that relate to epigenetic change and diet. Finally, we discuss different examples of maternal diets, their effect on outcomes, and their relationship with assisted reproductive technology (ART), including their implications on epigenetic modifications.

Therapeutic importance of Zishen Yutai Pill on the female reproductive health: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Zishen Yutai Pill (ZYP) is a widely used Traditional Chinese Medicine in Assisted Reproductive Technology (ART) medications, particularly in China. ZYP has a potential therapeutic role in human reproductive health, including in vitro fertilization embryo transfer and various reproductive disorders. The National Essential Medicine List of China has recently included the ZYP in Obstetrics and Gynecology medicine due to its significance in treating miscarriage and fertility associated disorders. Various clinical studies have demonstrated the importance of ZYP in improving the fertility and pregnancy rate. However, the pharmacological and toxicological actions of ZYP on reproductive health has been scantly reported.

AIM OF THE REVIEW

This review aims to emphasize the potential therapeutic effect of ZYP in ART and highlight its clinical significance in treating various reproductive disorders linked with hormonal balance, ovarian follicle development, menstrual cycle, uterine function and pregnancy. Additional insights on the safety evaluation of ZYP were elucidated by exploring an array of published experimental studies in various animal models with its molecular mechanism of action.

MATERIALS AND METHODS

The literature review was conducted across the databases such as PubMed, ScienceDirect, Google Scholar, China Biomedical Literature Database, China National Knowledge Infrastructure, Wanfang Database, International Clinical Trials Registry Platform and Cochrane Central Register of Controlled Trials with no time limit applied. The search terms used in this review include, 'Zishen Yutai Pills' and/or 'reproduction', 'assisted reproductive techniques', 'pregnancy', 'threatened abortion', 'miscarriage', 'fertility', 'infertility', 'disorders', 'women health', 'toxicity', and 'adverse effects'.

RESULTS

ZYP is a combination of fifteen traditional medicines and each of its components has various biological functions in humans. ZYP has improved the fertility and pregnancy rate through in vitro fertilization-embryo transfer. Further, various clinical studies have revealed that ZYP showed the curative effect for miscarriage, recurrent spontaneous abortion, menstrual disorder, luteal dysfunction, diminished ovarian reserve, polycystic ovary syndrome and premature ovarian insufficiency. The intervention of ZYP has multiple roles in reproductive functions such as regulation of ovulation, follicle development, menstrual flow, hormonal balance and endometrial thickness. The reproductive and toxicological reports in various animal models have highlighted the efficacy and safety of ZYP on the reproductive functions.

CONCLUSION

Nowadays, many problems are associated with maternal health, fertility and reproduction, due to the various physiological and environmental factors. The intervention of ART provides hope to infertile patients. Overall, this review provides insights on the therapeutic importance of ZYP in ART medications and treating various reproductive disorders.

The cell biology of fertilization: Gamete attachment and fusion

Fertilization is defined as the union of two gametes. During fertilization, sperm and egg fuse to form a diploid zygote to initiate prenatal development. In mammals, fertilization involves multiple ordered steps, including the acrosome reaction, zona pellucida penetration, sperm-egg attachment, and membrane fusion. Given the success of in vitro fertilization, one would think that the mechanisms of fertilization are understood; however, the precise details for many of the steps in fertilization remain a mystery. Recent studies using genetic knockout mouse models and structural biology are providing valuable insight into the molecular basis of sperm-egg attachment and fusion. Here, we review the cell biology of fertilization, specifically summarizing data from recent structural and functional studies that provide insights into the interactions involved in human gamete attachment and fusion.

Secular changes in human reproduction and assisted reproductive technologies

Since the middle to late 20th century the majority of children born in the developing world have been likely to enter into post-reproductive age. Currently, child mortality is at its lowest level in human history. While more children are living to post reproductive age, approximately 15% of couples are experiencing infecundity. This is either a result of one or both members of the couple being infecund, or, despite both being fecund, the interaction between them prevents fertility for some reason. Assisted reproductive technologies have provided many infertile couples an opportunity to have children. Assisted reproductive technologies operate by intervening and manipulating gametic and intrauterine natural selection. This paper discusses the possible influence of assisted reproductive technologies on child development. This paper outlines some of the reported changes in children resulting from assisted reproductive technologies. Although, few people are either aware or care about possible long term consequences of relaxed natural selection contributed by medical intervention (i.e. assisted reproductive technologies) we have little understanding to what extent such medical interference may affect long term fitness in humans.

Analyses of child cardiometabolic phenotype following assisted reproductive technologies using a pragmatic trial emulation approach

Assisted reproductive technologies (ART) are increasingly used, however little is known about the long-term health of ART-conceived offspring. Weak selection of comparison groups and poorly characterized mechanisms impede current understanding. In a prospective cohort (Growing Up in Singapore Towards healthy Outcomes; GUSTO; Clinical Trials ID: NCT01174875) including 83 ART-conceived and 1095 spontaneously-conceived singletons, we estimate effects of ART on anthropometry, blood pressure, serum metabolic biomarkers, and cord tissue DNA methylation by emulating a pragmatic trial supported by machine learning-based estimators. We find ART-conceived children to be shorter (-0.5 SD [95% CI: -0.7, -0.2]), lighter (-0.6 SD [-0.9, -0.3]) and have lower skinfold thicknesses (e.g. -14% [-24%, -3%] suprailiac), and blood pressure (-3 mmHg [-6, -0.5] systolic) at 6-6.5 years, with no strong differences in metabolic biomarkers. Differences are not explained by parental anthropometry or comorbidities, polygenic risk score, breastfeeding, or illnesses. Our simulations demonstrate ART is strongly associated with lower NECAB3 DNA methylation, with negative control analyses suggesting these estimates are unbiased. However, methylation changes do not appear to mediate observed differences in child phenotype.

Early Embryo Exposure to Assisted Reproductive Manipulation Induced Subtle Changes in Liver Epigenetics with No Apparent Negative Health Consequences in Rabbit

Embryo manipulation is a requisite step in assisted reproductive technology (ART). Therefore, it is of great necessity to appraise the safety of ART and investigate the long-term effect, including lipid metabolism, on ART-conceived offspring. Augmenting our ART rabbit model to investigate lipid metabolic outcomes in offspring longitudinally, we detected variations in hepatic DNA methylation ART offspring in the F3 generation for embryonic exposure (multiple ovulation, vitrification and embryo transfer). Through adult liver metabolomics and proteomics, we identified changes mainly related to lipid metabolism (e.g., polyunsaturated fatty acids, steroids, steroid hormone). We also found that DNA methylation analysis was linked to changes in lipid metabolism and apoptosis genes. Nevertheless, these differences did not apparently alter the general health status. Thus, our findings suggest that ART is likely to be a player in embryo epigenetic events related to hepatic homeostasis alteration in adulthood.

Manual removal of the placenta and postpartum hemorrhage: A multicenter retrospective study

AIM

In postpartum women, retained placenta is diagnosed in the absence of signs of placental separation and expulsion, and requires manual removal of the placenta (MROP). MROP may lead to massive hemorrhage, hemodynamic instability, and the need for emergency interventions including blood transfusion, interventional radiology, and hysterectomy. In this study, we aimed to identify the risk factors for retained placenta requiring MROP after vaginal delivery and postpartum hemorrhage (PPH) following MROP.

METHODS

A multicenter retrospective study was performed using data from women who delivered at term between 2010 and 2018 at 13 facilities in Japan. Of 36 454 eligible women, 112 women who required MROP were identified. Multivariate logistic regression analyses were conducted to evaluate the risk factors for retained placenta and PPH following MROP.

RESULTS

A history of abortion, assisted reproductive technology (ART), instrumental delivery, and delivery of small-for-gestational-age infant were independent risk factors for MROP (adjusted odds ratios [95% confidence intervals]: 1.93 [1.28-2.92], 8.41 [5.43-13.05], 1.80 [1.14-2.82], and 4.32 [1.97-9.48], respectively). ART was identified as an independent risk factor for PPH (adjusted odds ratio [95% confidence interval]: 6.67 [2.42-18.36]) in patients who underwent MROP.

CONCLUSION

ART pregnancies significantly increased the risk of retained placenta requiring MROP and PPH. Our results suggest that clinicians need consider patient transfer to a higher-level facility and preparation of sufficient blood products before initiating MROP in cases of ART pregnancies. Our study may assist in identifying high-risk women for PPH before MROP and in guiding treatment decisions, especially in facilities without a blood bank.

Conception by fertility treatment and offspring deoxyribonucleic acid methylation

OBJECTIVE

To investigate whether deoxyribonucleic acid (DNA) methylation at birth and in childhood differ by conception using assisted reproductive technologies (ART) or ovulation induction compared with those in children conceived without fertility treatment.

DESIGN

Upstate KIDS is a matched exposure cohort which oversampled on newborns conceived by treatment.

SETTING

New York State (excluding New York City).

PATIENT(S)

This analysis included 855 newborns and 152 children at approximately 9 years of age.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

DNA methylation levels were measured using the Illumina EPIC platform. Single CpG and regional analyses at imprinting genes were conducted.

RESULT(S)

Compared to no fertility treatment, ART was associated with lower mean DNA methylation levels at birth in 11 CpGs (located in/near SYCE1, SPRN, KIAA2013, MYO1D, GET1/WRB-SH4BGR, IGF1R, SORD, NECAB3/ACTL10, and GET1) and higher mean methylation level in 1 CpG (KLK4; all false discovery rate P<.05). The strongest association (cg17676129) was located at SYCE1, which codes for a synaptonemal complex that plays a role in meiosis and therefore infertility. This CpG remained associated with newborn hypomethylation when the analysis was limited to those conceived with ICSI, but this may be because of underlying male infertility. In addition, nine regions in maternally imprinted genes (IGF1R, PPIEL, SVOPL GNAS, L3MBTL, BLCAP, HYMAI/PLAGL1, SNU13, and MEST) were observed to have decreased mean DNA methylation levels among newborns conceived by ART. In childhood, hypomethylation of the maternally imprinted gene, GNAS, persisted. No CpGs or regions were associated with ovulation induction.

CONCLUSION(S)

ART but not ovulation induction was associated with hypomethylation at birth, but only one difference at an imprinting region appeared to persist in childhood.

Growth in children conceived by ART

STUDY QUESTION

Is the growth pattern of children conceived by ART different compared to naturally conceived children.

SUMMARY ANSWER

Both ART and underlying parental subfertility may contribute to differences in early childhood growth between children conceived with and without the use of ART.

WHAT IS KNOWN ALREADY

Children conceived by ART weigh less and are shorter at the time of delivery. The extent to which differences in growth according to mode of conception persist during childhood, and the role of underlying parental subfertility, remains unclear.

STUDY DESIGN, SIZE, DURATION

We conducted a prospective study population-based study. We studied 81 461 children participating in the Norwegian Mother, Father and Child Cohort Study (MoBa) and 544 113 adolescents screened for military conscription.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Conception by ART as registered in the Medical Birth Registry. We compared maternally reported length/height and weight among children in MoBa from mid-pregnancy to age 7 according to mode of conception using mixed-effects linear regression. Differences in self-reported height and weight at 17 years of age at screening for military conscription were assessed with linear regression.

MAIN RESULTS AND THE ROLE OF CHANCE

At birth, children conceived by ART were shorter (boys −0.3 cm; 95% CI, −0.5 to −0.1), girls −0.4 cm; 95% CI, −0.5 to −0.3) and lighter (boys −113 grams; 95% CI, −201 to −25, girls −107 grams; 95% CI, −197 to −17). After birth, children conceived by ART grew more rapidly, achieving both greater height and weight at age 3. Children conceived by ART had a greater height up to age 7, but did not have a greater height or weight by age 17. Naturally conceived children of parents taking longer time to conceive had growth patterns similar to ART children. Children born after frozen embryo transfer had larger ultrasound measures and were longer and heavier the first 2 years than those born after fresh embryo transfer.

LIMITATIONS, REASONS FOR CAUTIONS

Selection bias could have been introduced due to the modest participation rate in the MoBa cohort. Our reliance on self-reported measures of length/height and weight could have introduced measurement error.

WIDER IMPLICATIONS OF THE FINDINGS

: Our findings provide reassurance that offspring conceived by ART are not different in height, weight or BMI from naturally conceived once they reach adolescence.

STUDY FUNDING/COMPETING INTEREST(S)

Research Council of Norway; Medical Research Council; National Institute of Environmental Health Sciences. The authors have no competing interest.

TRIAL REGISTRATION NUMBER

N/A.

Uterine lavage: ethics of research and clinical applications

Uterine lavage is presented as a way to perform aneuploidy screening without IVF. The feasibility of this method was tested in a research study. This study combined a number of highly contentious ethical issues: the creation of embryos for research (very early), abortion and (moderate) payments to research participants. It is concluded that the study largely fulfils the criteria of ethical research but that the researchers should have avoided a number of steps. These steps were the inclusion of infertility patients, the performance of the research in a middle-income country and the double destination of the embryos. The next question then becomes whether it would be acceptable to apply the method in a clinical setting. Two elements complicate the introduction in the clinic: low success rate of embryo collection and risk of unintended pregnancy. The application of the method in the clinic may lead to very complicated ethical and legal situations for which both patients and doctors should be prepared.

An EPIC predictor of gestational age and its application to newborns conceived by assisted reproductive technologies

Background

Gestational age is a useful proxy for assessing developmental maturity, but correct estimation of gestational age is difficult using clinical measures. DNA methylation at birth has proven to be an accurate predictor of gestational age. Previous predictors of epigenetic gestational age were based on DNA methylation data from the Illumina HumanMethylation 27 K or 450 K array, which have subsequently been replaced by the Illumina MethylationEPIC 850 K array (EPIC). Our aims here were to build an epigenetic gestational age clock specific for the EPIC array and to evaluate its precision and accuracy using the embryo transfer date of newborns from the largest EPIC-derived dataset to date on assisted reproductive technologies (ART).

Methods

We built an epigenetic gestational age clock using Lasso regression trained on 755 randomly selected non-ART newborns from the Norwegian Study of Assisted Reproductive Technologies (START)—a substudy of the Norwegian Mother, Father, and Child Cohort Study (MoBa). For the ART-conceived newborns, the START dataset had detailed information on the embryo transfer date and the specific ART procedure used for conception. The predicted gestational age was compared to clinically estimated gestational age in 200 non-ART and 838 ART newborns using MM-type robust regression. The performance of the clock was compared to previously published gestational age clocks in an independent replication sample of 148 newborns from the Prediction and Prevention of Preeclampsia and Intrauterine Growth Restrictions (PREDO) study—a prospective pregnancy cohort of Finnish women.

Results

Our new epigenetic gestational age clock showed higher precision and accuracy in predicting gestational age than previous gestational age clocks (R² = 0.724, median absolute deviation (MAD) = 3.14 days). Restricting the analysis to CpGs shared between 450 K and EPIC did not reduce the precision of the clock. Furthermore, validating the clock on ART newborns with known embryo transfer date confirmed that DNA methylation is an accurate predictor of gestational age (R² = 0.767, MAD = 3.7 days).

Conclusions

We present the first EPIC-based predictor of gestational age and demonstrate its robustness and precision in ART and non-ART newborns. As more datasets are being generated on the EPIC platform, this clock will be valuable in studies using gestational age to assess neonatal development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01055-z.

Association Between Assisted Reproductive Technology and White Matter Injury in Premature Infants: A Case-Control Study

Objectives: Whether there is a link between assisted reproductive technology (ART) and brain damage in premature infants remains unclear. The aim of this study was to determine whether premature infants conceived by ART are at a greater risk of developing white matter injury (WMI), as detected by magnetic resonance imaging (MRI) or diffusion-weighted imaging (DWI) within 14 days, than those naturally conceived (NC). Methods: A retrospective case-control study was conducted on singleton premature infants with a gestational age of ≥28 weeks and <34 weeks delivered between 2017 and 2019 at Shengjing Hospital, China Medical University. This study included 638 live births that were stratified into case group (n = 218) and control group (n = 420), depending on the presence or absence of WMI. The exposure proportion of ART was compared between the case and control groups, and a logistic regression model was used to identify whether ART was an independent risk factor for WMI. Results: In the univariate analysis, the exposure proportion of ART conception was higher in cases than in controls (12.84 vs. 7.38%, p = 0.024). According to the multivariable analysis, after adjustment for other variables, the association between ART and WMI remained significant (1.82; 95% confidence interval, 1.04-3.21; P = 0.038). Conclusions: Singleton premature infants conceived by ART have a higher risk of WMI than NC infants. Given that ART is an independent risk factor for WMI in premature infants, more attention should be paid to neurodevelopmental outcomes in this group.

The effects of assisted reproduction technologies on metabolic health and disease†

The increasing prevalence of metabolic diseases places a substantial burden on human health throughout the world. It is believed that predisposition to metabolic disease starts early in life, a period of great susceptibility to epigenetic reprogramming due to environmental insults. Assisted reproductive technologies (ART), i.e., treatments for infertility, may affect embryo development, resulting in multiple adverse health outcomes in postnatal life. The most frequently observed alteration in ART pregnancies is impaired placental nutrient transfer. Moreover, consequent intrauterine growth restriction and low birth weight followed by catch-up growth can all predict future obesity, insulin resistance, and chronic metabolic diseases. In this review, we have focused on evidence of adverse metabolic alterations associated with ART, which can contribute to the development of chronic adult-onset diseases, such as metabolic syndrome, type 2 diabetes, and cardiovascular disease. Due to high phenotypic plasticity, ART pregnancies can produce both offspring with adverse health outcomes, as well as healthy individuals. We further discuss the sex-specific and age-dependent metabolic alterations reflected in ART offspring, and how the degree of interference of a given ART procedure (from mild to more severe manipulation of the egg) affects the occurrence and degree of offspring alterations. Over the last few years, studies have reported signs of cardiometabolic alterations in ART offspring that are detectable at a young age but that do not appear to constitute a high risk of disease and morbidity per se. These abnormal phenotypes could be early indicators of the development of chronic diseases, including metabolic syndrome, in adulthood. The early detection of metabolic alterations could contribute to preventing the onset of disease in adulthood. Such early interventions may counteract the risk factors and improve the long-term health of the individual.

Child health outcomes following fertility treatment and patient characteristics: discrepancies, limitations and prudence

We argue that increased risk for a variety of diseases in ART children has been consistently reaffirmed by different methods and in diverse populations, providing a methodological critique of recent sibling studies, which hold great potential for studying the risks of ART. A recent within-family analysis using a national population register holds a distinct size advantage over previous studies, and suggested that apparent risks to offspring may be attributable to birth order. However, limitations of the design may have resulted in an erroneous conclusion. We discuss the advantages of a frequently neglected sibling study design, which compares siblings born of surrogate motherhood. While uncertainty remains, the evidence points to elevated risk for ART offspring. It may therefore be prudent to call for an extension of preventive and precautionary decisions to the entire population, and to change informed consent to incorporate the long-term health consequences of fertility treatments.

Sex-specific epigenetic profile of inner cell mass of mice conceived in vivo or by IVF

The preimplantation stage of development is exquisitely sensitive to environmental stresses, and changes occurring during this developmental phase may have long-term health effects. Animal studies indicate that IVF offspring display metabolic alterations, including hypertension, glucose intolerance and cardiac hypertrophy, often in a sexual dimorphic fashion. The detailed nature of epigenetic changes following in-vitro culture is, however, unknown. This study was performed to evaluate the epigenetic (using whole-genome bisulfite sequencing (WGBS) and assay for transposase-accessible chromatin using sequencing (ATAC-seq)) and transcriptomic changes (using RNA-seq) occurring in the inner cell mass (ICM) of male or female mouse embryos generated in vivo or by IVF. We found that the ICM of IVF embryos, compared to the in-vivo ICM, differed in 3% of differentially methylated regions (DMRs), of which 0.1% were located on CpG islands. ATAC-seq revealed that 293 regions were more accessible and 101 were less accessible in IVF embryos, while RNA-seq revealed that 21 genes were differentially regulated in IVF embryos. Functional enrichment analysis revealed that stress signalling (STAT and NF-kB signalling), developmental processes and cardiac hypertrophy signalling showed consistent changes in WGBS and ATAC-seq platforms. In contrast, male and female embryos showed minimal changes. Male ICM had an increased number of significantly hyper-methylated DMRs, while only 27 regions showed different chromatin accessibility and only one gene was differentially expressed. In summary, this study provides the first comprehensive analysis of DNA methylation, chromatin accessibility and RNA expression changes induced by IVF in male and female ICMs. This dataset can be of value to all researchers interested in the developmental origin of health and disease (DOHaD) hypothesis and might lead to a better understanding of how early embryonic manipulation may affect adult health.

Development of children born from freeze-only versus fresh embryo transfer: follow-up of a randomized controlled trial

OBJECTIVE

To compare the longer-term development outcomes in children born after freeze-only versus fresh embryo transfer (ET) in women with an ovulatory cycle.

DESIGN

Long-term follow-up study (NCT04099784) of babies born alive after the first ET in a randomized controlled trial (RCT) comparing ongoing pregnancy and live birth rates after use of a freeze-only versus fresh ET strategy (NCT02471573).

SETTING

Private clinic.

PATIENT(S)

Of 391 couples randomized to each treatment group in the RCT, 132 (97 singleton/35 twins) and 123 (95 singleton/28 twins) in the freeze-only and fresh ET groups had live birth; 113 parents (86%) from the freeze-only group (147 babies) and 99 (80%) from the fresh ET group (120 babies) returned questionnaires for this follow-up study.

INTERVENTION(S)

Use of a freeze-only or fresh ET strategy after controlled ovarian hyperstimulation with a follicle-stimulating hormone/gonadotropin-releasing antagonist protocol.

MAIN OUTCOME MEASURE(S)

Developmental status at ≥2 years after birth, determined using the Developmental Red Flags and Ages & Stages Third Edition (ASQ-3) Questionnaires.

RESULT(S)

Mean age of children at the end of follow-up was 37 months. Height (95.0 ± 6.1 vs. 95.7 ± 5.6 cm) and weight (14.9 ± 2.6 vs. 14.8 ± 2.6 kg) were similar in the freeze-only and fresh ET groups (results were similar when singletons and twins were analyzed separately). Overall, ASQ-3 scores for problem solving were significantly better in the freeze-only versus fresh ET group (overall: 53.6 ± 8.4 vs. 51.1 ± 10.2), with no significant between-group difference when singletons (52.3 ± 10.1 vs. 51.0 ± 9.9) and twins (55.0 ± 5.5 vs. 51.4 ± 11.1) were analyzed separately. Fine motor skills scores were numerically higher (with P values approaching statistical significance) in the freeze-only versus fresh ET group in the overall analysis (47.8 ± 11.6 vs. 44.9 ± 12.6) and twins (49.85 ± 8.72 vs. 43.93 ± 12.71), but not singletons (46.0 ± 13.4 vs. 45.4 ± 12.6). The overall proportion of children with abnormal ASQ-3 (6.8% vs. 8.3%) or abnormal Red Flags (5.4% vs. 6.7%) findings in the freeze-only and fresh ET groups was low and did not differ significantly between groups.

CONCLUSION(S)

These data provide physicians with additional information on which to base decisions about the relative merits of different approaches to infertility treatment. There do not appear to be any grounds for concern about worse outcomes after use of a freeze-only strategy. However, additional studies comparing childhood development after a freeze-only strategy, fresh ET, and natural cycles are needed before firm conclusions can be drawn.