Assisted reproductive technology and somatic morbidity in childhood: a systematic review

Vitamin D3 among neonates born after in vitro fertilization compared with neonates from the general population

INTRODUCTION

Sufficient levels of vitamin D have been associated with higher chances for both clinical pregnancy and live birth among women undergoing assisted reproductive techniques, whereas low levels of maternal vitamin D have been associated with preeclampsia and late miscarriage. In Denmark, subgroups at risk for low vitamin D levels, including neonates and toddlers, are recommended to use supplementation. The aim was to study the level of vitamin D3 among neonates born after in vitro fertilization compared with neonates from the general population.

MATERIAL AND METHODS

In this cohort study a random sample of 1326 neonates representing the general population and 1200 neonates conceived by in vitro fertilization born in Denmark from 1995 to 2002 were identified from registries covering the whole Danish population. Information on use of assisted reproduction was collected from the Danish In Vitro Fertilization register, ICD-10 code: DZ358F. 25-Hydroxyvitamin D was measured from dried blood spots routinely collected by heel prick 48-72 h after birth and corrected according to the hematocrit fraction for capillary blood of neonates. Linear regression analysis was performed, both crude and adjusted, for predefined putative confounders, identified through directed acyclic graphs.

RESULTS

Vitamin D3 analysis could be performed from a total of 1105 neonates from the general population and 1072 neonates conceived by in vitro fertilization that were subsequently included in the study. The median vitamin D3 was 24.0 nmol/L (interquartile range [IQR] 14.1-39.3) and 33.0 nmol/L (IQR 21.3-48.8) among neonates from the general population and neonates conceived by in vitro fertilization, respectively. The adjusted mean difference between neonates from the general population and those conceived by in vitro fertilization was 6.1 nmol/L (95% confidence interval 4.1-8.1).

CONCLUSIONS

In this study, children born after in vitro fertilization have a higher vitamin D3 than a random sample of neonates in Denmark.

Preimplantation genetic testing in the current era, a review

BACKGROUND

Preimplantation genetic testing (PGT), also referred to as preimplantation genetic diagnosis (PGD), is an advanced reproductive technology used during in vitro fertilization (IVF) cycles to identify genetic abnormalities in embryos prior to their implantation. PGT is used to screen embryos for chromosomal abnormalities, monogenic disorders, and structural rearrangements.

DEVELOPMENT OF PGT

Over the past few decades, PGT has undergone tremendous development, resulting in three primary forms: PGT-A, PGT-M, and PGT-SR. PGT-A is utilized for screening embryos for aneuploidies, PGT-M is used to detect disorders caused by a single gene, and PGT-SR is used to detect chromosomal abnormalities caused by structural rearrangements in the genome.

PURPOSE OF REVIEW

In this review, we thoroughly summarized and reviewed PGT and discussed its pros and cons down to the minutest aspects. Additionally, recent studies that highlight the advancements of PGT in the current era, including their future perspectives, were reviewed.

CONCLUSIONS

This comprehensive review aims to provide new insights into the understanding of techniques used in PGT, thereby contributing to the field of reproductive genetics.

A North American study of anthropometric factors and semen quality

OBJECTIVE

To evaluate the association between anthropometric measures and semen parameters.

DESIGN

Cross-sectional study.

SUBJECTS

Male participants aged ≥21 years. We analyzed data from 659 males (1185 samples) participating in a semen testing substudy of the Pregnancy Online Study (PRESTO), a North American preconception cohort study. After enrollment, we invited males aged ≥21 years to perform at-home semen testing using the Trak system.

EXPOSURE(S)

Participants reported selected anthropometric variables (current weight, height, waist circumference, and weight at age 17 years) and covariate data via an online baseline questionnaire.

MAIN OUTCOME MEASURE(S)

We used generalized estimating equations models to estimate the percent difference in mean log-transformed semen parameter values and 95% confidence intervals (CI) for associations between selected anthropometric variables and semen volume (mL), sperm concentration (million/mL), and total sperm count (million), adjusting for sociodemographics, lifestyle factors, and medical history. We also evaluated World Health Organization-defined thresholds for low semen quality.

RESULT(S)

Percentage differences in mean log-transformed semen volume, sperm concentration, and total sperm count (95% CI) comparing current body mass index ≥35 vs. <25 kg/m2 were -6.3 (-15.8, 4.3), -6.4 (-24.6, 16.2), and -12.2 (-31.1, 11.8), respectively. Percentage differences (95% CIs) comparing waist circumferences of ≥42 vs. <31 inches were -4.2 (-15.0, 8.0), -6.4 (-27.6, 21.0), and -10.4 (-31.9, 17.9) for semen volume, sperm concentration, and total sperm count, respectively. Greater adult weight gain since age 17 years was associated with reduced semen volume (≥25 vs. <5 kg; percent difference, -9.7; 95% CI, -18.4, 0.1), but not sperm concentration or total sperm count. The highest categories of each anthropometric variable generally were associated with World Health Organization-defined low total sperm count (≤39 million).

CONCLUSION(S)

Selected anthropometric factors were associated modestly with poorer semen quality.

Long-Term Effects of ART on the Health of the Offspring

Assisted reproductive technologies (ART) significantly increase the chance of successful pregnancy and live birth in infertile couples. The different procedures for ART, including in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), intrauterine insemination (IUI), and gamete intrafallopian tube transfer (GIFT), are widely used to overcome infertility-related problems. In spite of its inarguable usefulness, concerns about the health consequences of ART-conceived babies have been raised. There are reports about the association of ART with birth defects and health complications, e.g., malignancies, high blood pressure, generalized vascular functional disorders, asthma and metabolic disorders in later life. It has been suggested that hormonal treatment of the mother, and the artificial environment during the manipulation of gametes and embryos may cause genomic and epigenetic alterations and subsequent complications in the health status of ART-conceived babies. In the current study, we aimed to review the possible long-term consequences of different ART procedures on the subsequent health status of ART-conceived offspring, considering the confounding factors that might account for/contribute to the long-term consequences.

Assisted reproductive technology and neonatal intensive care unit: A retrospective observational study from a single center

BACKGROUND

An increasing number of infants are being conceived using assisted reproductive technology (ART). The effects of infertility treatments (IFTs) on infant outcomes have been extensively debated; however, a consensus has not yet been reached. In the present study, we investigated the impact of IFTs on neonatal intensive care unit (NICU) managements using data collected at a single large NICU center.

METHODS

We retrospectively investigated patients admitted to the University of Tokyo Hospital NICU during three different time periods (2010, 2015, and 2020). We included 131, 201, and 323 infants, respectively, and compared a number of factors among groups classified by the mode of conception: spontaneous pregnancy (SP), non-ART (conceived with assisted ovulation or artificial insemination), and ART. We also compared the mode of conception among inborn singletons.

RESULTS

The rate of admission of ART infants significantly increased from 2010 (9.1%) to 2015 (22.9%) and 2020 (25.7%) (p values of <0.05 and <0.01, respectively). When compared among inborn singletons, ART infants were more often admitted to NICU (p < 0.01). Congenital anomalies and surgical interventions were significantly more frequent in the SP group than in the ART group (p < 0.01). No significant differences were observed in neonatal outcomes among ART infants from 2010 to 2015/2020.

CONCLUSIONS

The rate of ART infants admitted to the NICU has significantly increased, with ART pregnancies now accounting for 25% of admissions to the perinatal medical center. ART procedure may be a risk factor for NICU admission. Neonatal intensive care is becoming increasingly indispensable for ART pregnancies.

Comparative metabolomic profiling of women undergoing in vitro fertilization procedures reveals potential infertility-related biomarkers in follicular fluid

Infertility is a worldwide concern, affecting one in six couples throughout their reproductive period. Therefore, enhancing the clinical tools available to identify the causes of infertility may save time, money, and emotional distress for the involved parties. This study aims to annotate potential biomarkers in follicular fluid that are negatively affecting pregnancy outcomes in women suffering infertility-related diseases such as endometriosis, tuboperitoneal factor, uterine factor, and unexplained infertility, using a metabolomics approach through high-resolution mass spectrometry. Follicular fluid samples collected from women who have the abovementioned diseases and managed to become pregnant after in vitro fertilization procedures [control group (CT)] were metabolically compared with those from women who suffer from the same diseases and could not get pregnant after the same treatment [infertile group (IF)]. Mass spectrometry analysis indicated 10 statistically relevant differential metabolites in the IF group, including phosphatidic acids, phosphatidylethanolamines, phosphatidylcholines, phosphatidylinositol, glucosylceramides, and 1-hydroxyvitamin D3 3-D-glucopyranoside. These metabolites are associated with cell signaling, cell proliferation, inflammation, oncogenesis, and apoptosis, and linked to infertility problems. Our results indicate that understanding the IF's metabolic profile may result in a faster and more assertive female infertility diagnosis, lowering the costs, and increasing the probability of a positive pregnancy outcome.

Male personal heat exposures and fecundability: A preconception cohort study

BACKGROUND

Several studies indicate adverse effects of selected heat exposures on semen quality, but few studies have directly evaluated fertility as an endpoint.

OBJECTIVE

We evaluated prospectively the association between male heat exposures and fecundability, the per-cycle probability of conception.

MATERIALS AND METHODS

We analyzed data from 3041 couples residing in the United States or Canada who enrolled in a prospective preconception cohort study (2013-2021). At enrollment, males reported on several heat-related exposures, such as use of saunas, hot baths, seat heaters, and tight-fitting underwear. Pregnancy status was updated on female follow-up questionnaires every 8 weeks until conception or a censoring event (initiation of fertility treatment, cessation of pregnancy attempts, withdrawal, loss to follow-up, or 12 cycles), whichever came first. We used proportional probabilities regression models to estimate fecundability ratios (FR) and 95% confidence intervals (CIs) for the association between heat exposures and fecundability, mutually adjusting for heat exposures and other potential confounders.

RESULTS

We observed small inverse associations for hot bath/tub use (≥3 vs. 0 times/month: FR = 0.87, 95% CI: 0.70-1.07) and fever in the 3 months before baseline (FR = 0.94, 95% CI: 0.79-1.12; one cycle of follow-up: FR = 0.84, 95% CI: 0.64-1.11). Little association was found for sauna use, hours of laptop use on one's lap, seat heater use, time spent sitting, and use of tight-fitting underwear. Based on a cumulative heat metric, FRs for 1, 2, 3, and ≥4 versus 0 heat exposures were 0.99 (95% CI: 0.87-1.12), 1.03 (95% CI: 0.89-1.19), 0.94 (95% CI: 0.74-1.19), and 0.77 (95% CI: 0.50-1.17), respectively. Associations were stronger among men aged ≥30 years (≥4 vs. 0 heat exposures: FR = 0.60, 95% CI: 0.34-1.04).

CONCLUSION

Male use of hot tubs/baths and fever showed weak inverse associations with fecundability. Cumulative exposure to multiple heat sources was associated with a moderate reduction in fecundability, particularly among males aged ≥30 years.

Semen quality and reproductive hormones in sons of subfertile couples: a cohort study

OBJECTIVE

To study the associations between parental subfecundity, assessed by time to pregnancy and use of medically-assisted reproduction, and reproductive health of young men.

DESIGN

Cohort study.

SETTING

Denmark.

PATIENT(S)

A total of 1,058 men in the Fetal Programming of Semen quality cohort, a subcohort of the Danish National Birth Cohort.

INTERVENTION(S)

From 2017-2019, men were recruited and provided semen and blood samples. Information on parental time to pregnancy and use of medically-assisted reproduction (including type of treatment) as well as demographic, health, and lifestyle factors were available. We estimated the crude and adjusted relative percentage differences with 95% confidence intervals (CIs) in the outcomes according to time to pregnancy and use of medically-assisted reproduction, using multiple adjusted negative binomial regression analysis.

MAIN OUTCOME MEASURE(S)

Semen characteristics (semen volume, sperm concentration, total sperm count, sperm motility, and morphology), testicular volume, and reproductive hormone levels (follicle stimulating hormone, luteinizing hormone, testosterone, estradiol, sex hormone-binding globulin, and free androgen index).

RESULT(S)

Overall, semen quality and levels of reproductive hormones were not lower among sons of subfecund parents reporting a time to pregnancy >6 months or use of intrauterine insemination. Sons conceived after in vitro fertilization or intracytoplasmic sperm injection, had a higher semen concentration (29%; 95% CI, -7%-79%) and a higher percentage of sperm with normal morphology (20%; 95% CI, -8%-56%), but with 95% CI overlapping the null. Moreover, these sons had slightly higher estradiol levels (30%; 95% CI, 7%-57%). The absolute differences seen were small, and the clinical significance of these differences are unknown.

CONCLUSION(S)

We found no major difference in semen quality or reproductive hormones in sons conceived by subfertile couples or with the use of medically-assisted reproduction.

Early childhood respiratory tract infections according to parental subfertility and conception by assisted reproductive technologies

STUDY QUESTION

Are children conceived by ART or born to subfertile parents more susceptible to upper or lower respiratory tract infections (URTI, LRTI)?

SUMMARY ANSWER

ART-conceived children had a higher frequency of and risk of hospitalization for respiratory infections up to age 3, which was only partly explained by parental subfertility.

WHAT IS KNOWN ALREADY

Some studies report increased risks of infections in children conceived by ART. Results for URTIs and LRTIs are inconclusive, and the contribution of underlying parental subfertility remains unclear.

STUDY DESIGN, SIZE, DURATION

We included 84 102 singletons of the Norwegian Mother, Father and Child Cohort Study (MoBa) born between 1999 and 2009. Mothers reported time-to-pregnancy at recruitment and child history of, frequency of and hospitalization for, respiratory infections when the child was 6, 18 and 36 months old by questionnaires. Subfertility was defined as having taken 12 or more months to conceive. The Medical Birth Registry of Norway (MBRN) provided information on ART. URTI included throat and ear infections, while LRTI included bronchitis, bronchiolitis, respiratory syncytial virus and pneumonia.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used log-binomial regression to estimate risk ratios (RR) and 95% CI of any respiratory tract infection and hospitalization, and negative-binomial regression to calculate incidence rate ratios (IRR) and 95% CI for number of infections. We compared children conceived by ART, and naturally conceived children of subfertile parents, to children of fertile parents (<12 months to conceive) while adjusting for maternal age, education, BMI and smoking during pregnancy and previous livebirths. We accounted for dependency between children born to the same mother.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 7334 (8.7%) singletons were naturally conceived by subfertile parents and 1901 (2.3%) were conceived by ART. Between age 0 and 36 months, 41 609 (49.5%) of children experienced any URTI, 15 542 (18.5%) any LRTI and 4134 (4.9%) were hospitalized due to LRTI. Up to age 3, children conceived by ART had higher frequencies of URTI (adjusted IRR (aIRR) 1.16; 95% CI 1.05–1.28) and hospitalizations due to LRTI (adjusted RR (aRR) 1.25; 95% CI 1.02–1.53), which was not seen for children of subfertile parents. Children conceived by ART were not at higher risks of respiratory infections up to age 18 months; only at age 19–36 months, they had increased risk of any LRTI (aRR 1.16; 95% CI 1.01–1.33), increased frequency of LRTIs (IRR 1.22; 95% CI 1.02–1.47) and a higher risk of hospitalization for LRTI (aRR 1.35; 95% CI 1.01–1.80). They also had an increased frequency of URTIs (aIRR; 1.19; 95% CI 1.07–1.33). Children of subfertile parents only had a higher risk of LRTIs (aRR 1.09; 95% CI 1.01–1.17) at age 19–36 months.

LIMITATIONS, REASONS FOR CAUTION

Self-reported time-to-pregnancy and respiratory tract infections by parents could lead to misclassification. Both the initial participation rate and loss to follow up in the MoBa limits generalizability to the general Norwegian population.

WIDER IMPLICATIONS OF THE FINDINGS

ART-conceived children might be more susceptible to respiratory tract infections in early childhood. This appears to be only partly explained by underlying parental subfertility. Exactly what aspects related to the ART procedure might be reflected in these associations need to be further investigated.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was received from the Swiss National Science Foundation (P2BEP3_191798), the Research Council of Norway (no. 262700), and the European Research Council (no. 947684). All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

The continuing evolution of birth cohort studies: achievements and challenges

Well-designed birth cohorts are able to estimate prevalence/distribution of various health events/outcomes, and to link early-life origins with adult health and function. The past two decades have seen a surge in the establishment of new birth cohorts and their accompanying research. We discussed distinct designs of current birth cohort studies, reviewed their achievements, and highlighted insights obtained from birth cohort studies, as well as challenges we are facing. Birth cohort studies are providing increasing opportunities to identify determining factors for short- and long-term health, yielding substantial evidence to uncover biological mechanisms of diseases and phenotypes, and providing further insights for public health. Dynamic monitoring, accurate measurements, long-term follow-ups and collaborative efforts are warranted in new birth cohorts to elucidate the nature of life course relationships in contemporary generation.

Maternal advanced age, single parenthood, and ART increase the risk of child morbidity up to five years of age

Background

Advanced maternal age, single status and use of assisted reproductive technology (ART) are increasing in mothers in high-income countries, and all are known risk factors for negative obstetric outcomes. Less is known about their long-term consequences for childhood morbidity. Thus, the aim of this study was to investigate morbidity up to five years of age, in the children of older, single, and/or ART-treated mothers.

Methods

A cross-sectional using Swedish registers was performed comprising 23 772 children. The prevalence of diagnosis and the number of hospital visits for specialist care, were compared and analyzed in relation to maternal age at childbirth, maternal civil status, and mode of conception. The odds ratio for specialized care within each ICD-chapter were estimated using single and multiple logistic regression.

Results

Children born to single mothers and children conceived using ART had significantly more outpatient visits for specialist care and significantly more diagnoses compared to children with married/cohabiting mothers, and spontaneously conceived children. Children born to mothers of advanced maternal age (≥40) had fewer in- and outpatient visits. However, they were significantly more often diagnosed within ICD-chapters XVI, XVII i.e., they experienced more morbidity in the neonatal period.

Conclusion

The results indicate that children born to single mothers and children of ART-treated mothers have a higher morbidity and consume more specialist care than children of married/cohabiting and spontaneously pregnant mothers. We conclude that the use of ART, maternal single status and advanced maternal age are risk factors of importance to consider in pediatric care and when counseling women who are considering ART treatment.

Asthma and allergies in offspring conceived by ART: a systematic review and meta-analysis

BACKGROUND

Currently, 1 in 25 children born in Australia are conceived through ARTs such as IVF and ICSI. Worldwide over 8 million children have been born after ART. There is evidence that these children are at an increased risk of congenital malformations, preterm birth, low birth weight and neonatal morbidity. However, studies on long-term health outcomes of offspring conceived after ART are lacking. Atopic disorders, such as asthma, atopic dermatitis and various allergies are increasingly common within society, and concerns have been raised that ART increases the risk of atopy amongst offspring.

OBJECTIVE AND RATIONALE

The aim of this study was to systematically summarise and quantify the risk of atopic disorders in offspring conceived with ART compared to those conceived without ART.

SEARCH METHODS

A systematic review was conducted according to the PRISMA guidelines. Several systematic searches were performed in the following international databases: Medline, Embase, Cinahl, PsychINFO, AMED, Global Health and ISI Web of Science. Search terms utilised were all terms pertaining to ART, IVF, ICSI, asthma, atopic dermatitis and allergies. The search period was 1978-2021. Included observational studies stated a primary outcome of asthma or allergies in offspring conceived after ART, with a comparison group conceived without ART. Individual studies were scored on quality and risk of bias, using the Newcastle-Ottawa scale (NOS).

OUTCOMES

There were 26 studies which met the inclusion criteria; of these, 24 studies investigated asthma in offspring conceived after ART. While 10 studies, including the two largest population-based studies, reported a significantly increased risk of asthma in offspring conceived after ART (adjusted odds ratio (aOR) range: 1.20-2.38), 14 smaller cohort studies found no difference (aOR range 0.70-1.27). In the meta-analysis of the 14 highest-quality studies (NOS ≥ 7), a modest yet significantly increased risk of asthma was demonstrated in offspring conceived after ART [risk ratio (RR) 1.28 (1.08-1.51)]. Although heterogeneity in these 14 studies was high (I2 = 85%), the removal of outliers and high weight studies significantly reduced heterogeneity (I2 = 0% and I2 = 34% respectively) while still demonstrating a significantly increased risk [RR 1.19 (1.10-1.28) and RR 1.31 (1.03-1.65), respectively]. The increased asthma risk was also observed in most subgroup and sensitivity analyses. The allergy rates were not increased in offspring conceived after ART in 9 of 12 studies (aOR range 0.60-1.30). In summary, the findings of this systematic review and meta-analysis suggest a trend towards a significantly increased risk of asthma, but not allergies, in offspring conceived after ART. There was no evidence of publication bias in the asthma studies and minimal evidence of publication bias in the allergy studies (both P > 0.05).

WIDER IMPLICATIONS

Asthma brings considerable burden to the quality of life of individuals and to society. Hence, it is of great importance to untangle potential causal pathways. Although ART use is common, knowledge about its long-term health effects is required to provide evidence-based advice to couples considering ART, and to be vigilant for any potential adverse health effects on offspring conceived after ART.

Association between childhood asthma and history of assisted reproduction techniques: a systematic review and meta-analysis

Genetic and environmental factors during early development may influence lung growth and impact lung function. We performed a meta-analysis of epidemiological studies examining the association between conception history of assisted reproduction techniques (ART) and childhood asthma. We searched PubMed and Embase up to November 2020 for relevant observational studies and synthesized data data under a fixed or random effects model as appropriate. Heterogeneity was assessed using the I² metric. We identified 13 individual studies including 3,226,386 participants. We did not observe a statistically significant association between ART and physician-diagnosed asthma (n = 9, random OR 1.16; 95% CI 0.94-1.43; I² 61%). We observed a statistically significant association between ART and prescription of asthma medications (n = 6, fixed OR 1.27; 95% CI 1.23-1.32; I² 0%). Wheezing was also associated with ART (n = 4, fixed OR 1.71; 95% CI 1.08-2.72; I² 0%). When we combined studies using any asthma definition, a statistically significant association was observed (random OR 1.19; 95% CI 1.05-1.34; I² 80%).Conclusion: The available observational evidence suggests that the risk of asthma is higher among children born after ART. The mechanism and potential sources of bias behind this association are under scrutiny, and further work is needed to establish causality. What is Known: • "Positive" epidemiological signals for the association between assisted reproduction techniques and asthma stemming from large studies were not replicated by subsequent research. • Any available research synthesis effort so far bears no quantitative aspect. What is New: • The available observational evidence suggests that the risk of asthma is higher among children born after ART. • The mechanism and potential sources of bias behind this association are under scrutiny.

Fertility treatment with clomiphene citrate and childhood epilepsy: a nationwide cohort study

STUDY QUESTION

Is fertility treatment with clomiphene citrate associated with an increased risk of childhood epilepsy, including specific subtypes of epilepsy?

SUMMARY ANSWER

Fertility treatment with clomiphene citrate may be associated with a small increased risk of idiopathic generalized epilepsy and focal epilepsy in childhood.

WHAT IS KNOWN ALREADY

Clomiphene citrate is among the most commonly prescribed drugs for fertility treatment. However, concerns have been raised as to whether the treatment may harm the developing fetus.

STUDY DESIGN, SIZE, DURATION

This nationwide cohort study included all pregnancies in Denmark from 1 July 1995 resulting in a live-born singleton child before 31 December 2013. The children were followed until 31 December 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Children conceived after fertility treatment with clomiphene citrate were identified from the Danish National Prescription Registry. The primary outcomes were childhood epilepsy, idiopathic generalized epilepsy, and focal epilepsy identified from the Danish National Patient Register and from antiepileptic drug prescriptions in the Danish National Prescription Registry. All analyses were conducted using Cox proportional hazards regression.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 1 081 291 pregnancies were included; 12 644 children (1.2%) developed epilepsy. Fertility treatment with clomiphene citrate was associated with a small increased risk of childhood epilepsy (hazard ratio [HR]: 1.10; 95% CI: 1.00-1.22), idiopathic generalized epilepsy (HR: 1.41; 95% CI: 1.16-1.72), and focal epilepsy (HR: 1.26; 95% CI: 1.04-1.53).

LIMITATIONS, REASONS FOR CAUTION

The increased risk of idiopathic generalized epilepsy may be due to confounding from time stable parental characteristics related to treatment with clomiphene citrate, since the association was strongest with the lowest administered dosage of clomiphene citrate prior to conception, and the association disappeared in a sibling analysis.

WIDER IMPLICATIONS OF THE FINDINGS

The increased risk of focal epilepsy may be related to the hormonal treatment, since the association tended to increase with increasing cumulative dosage of clomiphene citrate prior to conception, and the association persisted in a sibling analysis. This finding may be of clinical importance, since alternative hormones are available for fertility treatment.

STUDY FUNDING/COMPETING INTEREST(S)

Financial support from Aarhus University and the Aase and Ejnar Danielsen Foundation. U.S.K. received personal teaching fees from Merck, outside the submitted work.

TRIAL REGISTRATION NUMBER

N/A.

Ninth-grade school achievement in Danish children conceived following fertility treatment: a population-based cohort study

OBJECTIVE

To assess whether academic achievement among children conceived following fertility treatment is different from that of children born to fertile women while also considering the underlying infertility.

DESIGN

Population-based cohort study.

SETTING

Denmark.

PATIENT(S)

The study population consisted of all 154,536 firstborn, live-born, singleton children in Denmark between 1995 and 2000 who completed their ninth grade with an examination.

INTERVENTION(S)

The Danish Infertility Cohort was used to identify children conceived after fertility treatment (n = 10,099), and information on mean school marks was obtained from Statistics Denmark.

MAIN OUTCOME MEASURE(S)

Linear regression models were used to estimate mean differences (MDs) and 95% confidence intervals (CIs). Multiple logistic regression models were used to estimate odds ratios (OR) and 95% CI of not passing the ninth-grade examination.

RESULTS

The crude overall mean marks for children conceived after the various fertility treatment procedures were in general higher than in children born to fertile women. However, after adjustment for potential confounders, the overall mean marks were statistically significantly lower for children conceived after the various fertility treatment procedures (e.g., any fertility treatment: MD -0.13; 95% CI -0.18, -0.08) compared with children born to fertile women. Further, children conceived after any fertility treatment had a statistically significant lower crude likelihood of not passing the ninth-grade examination (OR 0.66; 95% CI 0.53, 0.81) compared with children born to fertile women, whereas no difference was observed in the confounder adjusted analyses (OR 1.15; 95% CI 0.89, 1.49). When children born to women requiring fertility assistance but without fertility treatment in the index pregnancy were used as a reference group, no differences in the adjusted overall mean marks and the likelihood of not passing the ninth grade with an examination were observed.

CONCLUSION

Our findings indicate that fertility treatment per se is not associated with lower school marks and the likelihood of not passing the ninth grade with an examination. Hence, we suggest that factors related to both fertility problems and cognitive development may more likely explain the slightly lower academic performance (i.e., modest lower mean marks) among children conceived after fertility treatment.

Risk of febrile seizures among children conceived following fertility treatment: A cohort study

BACKGROUND

Studies have shown that fertility treatment in mothers is associated with neurological problems in children. However, knowledge about any association between maternal use of fertility treatment and febrile seizures in children is lacking.

OBJECTIVE

To determine whether maternal use of fertility treatment is associated with febrile seizures in children.

METHODS

All liveborn children in Denmark during 1996-2012 (n = 1 065 901) were linked with the Danish Infertility Cohort and the Danish national registers and were followed from one year of age until the first episode of a febrile seizure, death, emigration, loss to follow-up, or end of follow-up (December 2015). Cox proportional hazard regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) with adjustment for potential confounders.

RESULTS

Approximately 16% children (n = 172 140) were conceived by infertile women, and approximately 3% (n = 34 082) were diagnosed with febrile seizures during follow-up. Compared with children conceived by fertile women, children conceived following any fertility treatment (HR 1.11, 95% CI 1.06, 1.16), following specific fertility treatment, for example IVF (HR 1.15, 95% CI 1.05, 1.25), ICSI (HR 1.20, 95% CI 1.10, 1.32), and following fertility drugs (HR 1.06, 95% CI 1.00, 1.11) had slight increase in risk of febrile seizures, after adjusting for calendar year of birth, parental age, education, parity status, and maternal smoking during pregnancy. The associations were unchanged when children conceived naturally by infertile women were used as the reference group.

CONCLUSIONS

Children conceived following fertility treatment had slightly increased relative risk for febrile seizures.

Cancer Risk in Children and Young Adults (Offspring) Born after Medically Assisted Reproduction: A Systematic Review and Meta-Analysis

Many studies have investigated the relationship between medically assisted reproduction (MAR) and health outcomes, particularly cancer, in the offspring. This meta-analysis investigated the association between MAR and childhood cancer. Data sources were PubMed, Scopus, and Web of Science up until June 2018. From the selected studies, we extracted the cancer risk estimates of the exposure of interest (MAR, assisted reproductive technology—ART, and in fitro fertilization—IVF). We conducted the meta-analysis using a random effects model. The outcomes of interest were childhood cancers, classified according to the international classification of childhood cancer (ICCC-3). In our meta-analysis (18 cohort and 15 case-control studies) the overall cancer risk was significantly increased in children conceived by MAR, ART, or IVF. MAR and ART significantly increased the risk for hematological tumors, hepatic tumors, and sarcomas (odds ratio (OR) 1.54; 95% CI 1.18–2.02 and OR 1.92; 95% CI 1.34–2.74, respectively). MAR increased acute myeloid leukemia risk (OR 1.41; 95% CI 1.02–1.95) and ART increased neural cancer risk (OR 1.21; 95% CI 1.01–1.46). Our results suggest an increased risk of cancer in children conceived by MAR. Further studies are needed to investigate the impact of fertility treatments, parental subfertility status, and their association on health outcomes in the offspring.

Risk of juvenile idiopathic arthritis among children conceived after fertility treatment: a nationwide registry-based cohort study

STUDY QUESTION

Is the risk of juvenile idiopathic arthritis (JIA) increased in children conceived after fertility treatment, and is an observed association caused by specific types of fertility treatment or by factors associated with the underlying infertility?

SUMMARY ANSWER

The risk of JIA in children conceived after fertility treatment (any and specific types of fertility treatment) was not convincingly affected when compared with children born to fertile women.

WHAT IS KNOWN ALREADY

It has been suggested that fertility treatment may affect the development of the immune system and thereby increase the risk of developing autoimmune diseases, including JIA.

STUDY DESIGN, SIZE, DURATION

This retrospective population-based cohort study included all live-born children in Denmark between 1 January 1996 and 31 December 2012 (n = 1 084 184). The study population was followed from date of birth until first diagnosis of JIA as registered in the Danish National Patient Registry, date of 16th birthday, date of emigration, date of death or end of follow-up (31 December 2014), whichever occurred first.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study cohort was linked to the Danish Infertility Cohort in order to identify children born to women with fertility problems (n = 174 702) and fertility treatment (n = 89 931). Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

During a median follow-up period of 10.3 years, 2237 children were diagnosed with JIA. Children born to women with fertility problems had an increased risk of JIA (HR 1.18, 95% CI 1.05-1.32) compared with children born to fertile women. However, the risk was not increased in children conceived after any fertility treatment (HR 1.11; 95% CI 0.95-1.29), or after specific types of fertility treatment being ART (HR 1.05; 95% CI 0.83-1.33), IVF (HR 1.01; 95% CI 0.73-1.38), ICSI (HR 0.98; 95% CI 0.64-1.50) or any fertility drugs (HR 1.10; 95% CI 0.94-1.28) compared with children born to fertile women. The associations between fertility treatment and JIA were also assessed by using children born to women with fertility problems without fertility treatment in the index pregnancy as a reference group, however, the findings did not change substantially.

LIMITATIONS REASONS FOR CAUTION

Despite a large study population, the statistical precision in some subgroup analyses may be affected due to the low number of JIA cases. There may be some misclassification of fertility problems, as some women have undiagnosed fertility problems and are therefore not included in the Danish Infertility Cohort; potentially leading to slight attenuation of the association between fertility problems and JIA.

WIDER IMPLICATIONS OF THE FINDINGS

The results are based on national data and our findings can therefore be applied to other similar populations. Our results indicate that fertility treatment per se do not increase the risk of JIA but merely that the increased risk of JIA observed among children born to women with fertility problems may be due to underlying factors related to both infertility and JIA. However, as this is the first large study in this field, further studies are needed to confirm our findings.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by grants from the Jascha Foundation, the Aase and Ejner Danielsens Foundation and The Danish Rheumatism Association. All authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Parental time to pregnancy, medically assisted reproduction and pubertal development in boys and girls

STUDY QUESTION

Does parental fertility, measured by time to pregnancy (TTP), or use of medically assisted reproduction (MAR) affect pubertal development in the offspring?

SUMMARY ANSWER

Neither TTP nor type of MAR treatment had clinically relevant implications for mean age at achieving individual pubertal milestones or overall timing of puberty in boys and girls.

WHAT IS KNOWN ALREADY

Parental TTP and MAR have been associated with impaired semen quality in adult sons. Timing of puberty reflects earlier signals of reproductive health, but it remains unclear whether parental fertility or MAR affects pubertal development, especially in the growing generation of children conceived by IVF or ICSI.

STUDY DESIGN, SIZE, DURATION

In this study, 15 819 children born by mothers in the Danish National Birth Cohort from 2000 to 2003 participated in a nationwide puberty cohort (participation rate = 70%). Parental TTP and use of MAR were reported by mothers in early pregnancy and children’s pubertal development data was self-recorded in web-based questionnaires from 11 years of age and 6 monthly throughout puberty (2012–2018).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Pubertal development in children (of planned pregnancies, n = 13 285) born by untreated subfecund (TTP: 6–12 months) (n =2038), untreated severely subfeund (TTP: >12 months) (n = 1242), treated subfecund (n = 230) and treated severely subfecund (n = 1234) parents were compared to children born to more fertile parents (TTP: ≤5 months). We estimated mean monthly differences in mean age at achieving individual pubertal milestones (i.e. age at menarche, voice break, first ejaculation and Tanner stages 2, 3, 4 and 5 for breast or genital development and pubic hair growth) and a combined indicator of timing of puberty. Further, we compared mean age at achieving the individual pubertal milestones in children born by use of IVF or ICSI (n = 480) with children born by controlled ovarian stimulation or ovulation induction with or without intrauterine insemination (n = 902).

MAIN RESULTS AND THE ROLE OF CHANCE

We found tendencies towards slightly later mean age at male pubertal timing and slightly earlier mean age at female pubertal timing among children born by untreated subfecund, treated subfecund, untreated severely subfecund and treated severely subfecund parents. There were no specific patterns with increasing TTP, use of MAR nor type of MAR treatment, and the magnitude of the mean differences for individual milestones and overall timing of puberty were small, i.e. 0.9 months (95% CI: −1.0; 2.8) for first ejaculation and −0.5 months (95% CI: −2.0; 1.0) months for age at menarche in boys and girls, respectively, born by treated severely subfecund parents when compared with children born by more fertile parents.

LIMITATIONS, REASONS FOR CAUTION

Non-differential misclassification of the self-reported information on parental TTP and pubertal development in the offspring may serve as an alternative explanation of the findings, possibly biasing the estimates towards the null. The information on pubertal development was collected from around 11 years of age and onwards.

WIDER IMPLICATIONS OF THE FINDINGS

This study adds to the growing body of literature suggesting only limited harmful effects of parental subfecundity and MAR on offspring’s long-term growth and development.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Danish Council for Independent Research [DFF 4183-00152]; and the Faculty of Health at Aarhus University. The authors have no financial relationships or competing interests to disclose.

Serum levels of trace elements in children born after assisted reproductive technology

INTRODUCTION

The health and development of newborn children born via assisted reproductive technology (ART), as well as their health in adulthood, have raised great concern. This study was designed to investigate whether ART children have differences in the levels of trace elements compared with naturally conceived children.

METHODS

This study included those ART children and controls aged 1 to 12 years assessed with a follow-up protocol. Serum levels of the trace elements zinc, copper, iron, calcium, magnesium and lead were determined and analyzed.

RESULTS

There were no significant differences in age, gender or body weight between the ART and control groups. There were no significant differences in the rates of deficiency or excess of trace elements between the two groups. Serum lead levels in children born via ART were significantly higher than those in the controls, whereas the levels of zinc and iron were significantly decreased in the ART group, although these levels were still within the normal ranges.

DISCUSSION

These results indicate the need to monitor the blood levels of zinc, iron and lead in ART children aged 1-6 years old. These findings contribute to our understanding on the long-term safety of ART and may facilitate screening for potential diseases related to trace elements.

Fertility Treatment and Childhood Epilepsy: A Nationwide Cohort Study

BACKGROUND

Fertility treatment includes hormonal stimulation of the woman and in vitro manipulation of gametes and embryos that may influence prenatal brain development. We aimed to investigate the association between fertility treatment and childhood epilepsy, including specific types of treatment and indications, as well as subtypes of epilepsy.

METHODS

In this nationwide birth cohort study, we included all pregnancies in Denmark resulting in live-born singletons, 1995-2003. Children conceived by fertility treatment and children developing epilepsy (until 2013) were identified from Danish national registers.

RESULTS

A total of 565,116 pregnancies were included; 8,071 children (1.4%) developed epilepsy. Children conceived after ovulation induction or intrauterine insemination had a slightly higher risk of childhood epilepsy (hazard ratio [HR]: 1.15; 95% confidence interval [CI]: 1.00, 1.31). The association was more pronounced for the subtypes idiopathic generalized and focal epilepsy. Regarding the specific hormonal treatments, only clomiphene citrate was associated with an increased risk of childhood epilepsy, also in a sibling analysis (HR: 2.07; 95% CI: 1.05, 4.08). In vitro fertilization or intracytoplasmic sperm injection was not associated with an overall increased risk of childhood epilepsy but with idiopathic generalized epilepsy (HR: 1.43; 95% CI: 0.99, 2.05). No clear associations were seen regarding other treatment types or indications.

CONCLUSIONS

Children conceived by ovulation induction or intrauterine insemination with clomiphene citrate may be at slightly increased risk of childhood epilepsy. Furthermore, children conceived by in vitro fertilization or intracytoplasmic sperm injection may be at slightly increased risk of idiopathic generalized epilepsy.

Literature review on cancer risk in children born after fertility treatment suggests increased risk of haematological cancers

Medically assisted fertility treatment, including assisted reproductive technology (ART), is increasingly being used and the subsequent child health outcomes are of interest. Some studies have suggested an elevated risk of somatic morbidity, while others have reported an elevated cancer risk. This review summarises the literature on fertility treatments and childhood cancer, based on 23 cohort and case-control studies.

CONCLUSION

The findings varied, but reassuring results on overall childhood cancer and fertility treatment were observed. However, some studies suggested an elevated risk of haematological cancers. More large population-based studies are needed, and the growing population of ART children should be monitored.

Fertility treatment and childhood type 1 diabetes mellitus: a nationwide cohort study of 565,116 live births

OBJECTIVE

To investigate the association between specific types of fertility treatment and childhood type 1 diabetes mellitus.

DESIGN

Nationwide birth cohort study.

SETTING

Not applicable.

PATIENT(S)

All pregnancies resulting in a live-born singleton child in Denmark from 1995 to 2003.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Childhood type 1 diabetes mellitus identified from redeemed prescriptions for insulin until 2013.

RESULT(S)

The study included 565,116 singleton pregnancies. A total of 14,985 children were conceived by ovulation induction or intrauterine insemination, and 8,490 children were conceived by in vitro fertilization or intracytoplasmic sperm injection. During the follow-up period, 2,011 (0.4%) children developed type 1 diabetes mellitus. The primary analyses showed no association between fertility treatment and childhood type 1 diabetes mellitus. In secondary analyses, ovulation induction or intrauterine insemination with follicle-stimulating hormone was associated with an increased risk of type 1 diabetes mellitus (hazard ratio 3.22; 95% confidence interval 1.20 to 8.64). No clear associations were seen with other types of fertility treatment or with specific treatment indications.

CONCLUSION(S)

No association between fertility treatment and childhood type 1 diabetes mellitus was found. Ovulation induction or intrauterine insemination with follicle-stimulating hormone may be associated with an increased risk of childhood type 1 diabetes mellitus. However, this finding may be due to chance or to confounding by indication and thus requires further investigation.

Parental Infertility, Fertility Treatment, and Childhood Epilepsy: A Population-Based Cohort Study

BACKGROUND

A few studies have indicated an increased risk of epilepsy in children conceived by fertility treatment possibly due to characteristics of the infertile couple rather than the treatment. We therefore aimed to investigate the association between parental infertility, fertility treatment, and epilepsy in the offspring, including the subtypes of epilepsy; idiopathic generalised epilepsy and focal epilepsy.

METHODS

This cohort included all pregnancies resulting in liveborn singletons from the Aarhus Birth Cohort, Denmark (1995-2013). Information on time to pregnancy and fertility treatment was obtained from pregnancy questionnaires in early pregnancy. Children developing epilepsy were identified from the Danish National Patient Register and the Danish National Prescription Registry until 2013. Data were analysed using Cox proportional hazards regression adjusted for potential confounders.

RESULTS

A total of 60 440 pregnancies were included, and 0.8% of the children developed epilepsy.The primary analyses showed no association between parental infertility or fertility treatment, and the overall risk of childhood epilepsy (hazard rate ratios (HRs); 95% confidence intervals (CIs): 1.08 (0.73, 1.60) and 1.04 (0.71, 1.52)). In secondary analyses, both parental infertility and fertility treatment were associated with an increased risk of idiopathic generalised epilepsy (HRs and 95% CIs: 2.25 (1.10, 4.58) and 2.45 (1.26, 4.75)). No association was seen for focal epilepsy.

CONCLUSION

Parental infertility or fertility treatment was not associated with an overall risk of childhood epilepsy. Parental infertility may be associated with an increased risk of idiopathic generalised epilepsy; a subtype of epilepsy believed to be of genetic origin.

Risk of Cancer in Children Conceived by Assisted Reproductive Technology

BACKGROUND AND OBJECTIVE

An increasing number of children are born after assisted reproductive technology (ART), and monitoring their long-term health effects is of interest. This study compares cancer risk in children conceived by ART to that in children conceived without.

METHODS

The Medical Birth Registry of Norway contains individual information on all children born in Norway (including information of ART conceptions). All children born between 1984 and 2011 constituted the study cohort, and cancer data were obtained from the Cancer Registry of Norway. Follow-up started at date of birth and ended on the date of the first cancer diagnosis, death, emigration, or December 31, 2011. A Cox proportional hazards model was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) of overall cancer risk between children conceived by ART and those not. Cancer risk was also assessed separately for all childhood cancer types.

RESULTS

The study cohort comprised 1 628 658 children, of which 25 782 were conceived by ART. Of the total 4554 cancers, 51 occurred in ART-conceived children. Risk of overall cancer was not significantly elevated (HR 1.21; 95% CI 0.90-1.63). However, increased risk of leukemia was observed for children conceived by ART compared with those who were not (HR 1.67; 95% CI 1.02-2.73). Elevated risk of Hodgkin's lymphoma was also found for ART-conceived children (HR 3.63; 95% CI 1.12-11.72), although this was based on small numbers.

CONCLUSIONS

This population-based cohort study found elevated risks of leukemia and Hodgkin's lymphoma in children conceived by ART.