Fertility treatment and child intelligence, attention, and executive functions in 5-year-old singletons: a cohort study

The association between type of conception through medically assisted reproduction and childhood cognition: a Danish population-wide cohort study

BACKGROUND

Previous research has indicated that children conceived through medically assisted reproduction (MAR) generally have cognitive outcomes comparable to or better than naturally conceived children. However, previous studies have been limited in their ability to examine this relationship at a population level and consider variations across different types of MAR.

METHODS

This study utilizes data from all live births in Denmark between 2006 and 2009 (n = 259 608), including a subset of births resulting from MAR conceptions (n = 13 566). The dependent variable is the standardized test scores obtained in the second and third grades of primary schools. A comparison is made between the test scores of children spontaneously conceived (SC) and those conceived through intrauterine insemination (IUI) and assisted reproductive technologies (ART). Ordinary least squares regressions are employed, with a baseline model adjusted only for birth year, as well as models that additionally account for conception-related confounders and sociodemographic family characteristics.

RESULTS

In the baseline analysis, ART- and IUI-conceived children displayed better test scores compared with their SC peers. However, after adjusting for relevant factors, ART-conceived children performed worse than SC peers, while IUI-conceived children performed equally well as SC peers and better than ART-conceived children.

CONCLUSIONS

These results likely reflect differences in the selection process of potential parents into the type of MAR, as well as the consequences of variations in fecundability. Nevertheless, the differences observed across conception types were overshadowed by test score disparities in socioeconomic background.

Intelligence, motoric and psychological outcomes in children from different ART treatments: a systematic review and meta-analysis

BACKGROUND

Subtle abnormalities in children's intelligence, motor skills, and psychology from various assisted reproductive treatments (ARTs) might be underdiagnosed. Understanding the prognosis of intelligence, motor skills, and psychology in children from ART would provide parents with reasonable expectations and enable them to plan relevant support to achieve the optimum potential in ART children.

METHODS

We searched PubMed, EMBASE, Ovid, Google Scholar, and Scopus databases until April 13, 2021, to identify relevant studies. Thirty-four studies met the inclusion and exclusion criteria. The meta-analysis employed a standardized mean difference model. The outcome of this study is to compare intelligence quotient (IQ), motoric ability, and behavioral problems between all ARTs, in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) to naturally conceived (NC) children. Subdomains of intelligence based on the Cattell, Horn, and Carroll Model (CHC Model) of cognitive architecture, including fluid reasoning, short-term and working memory, processing speed, visual-spatial ability, long-term memory retrieval, and crystalized intelligence (knowledge), were evaluated and summarized in details. Motor skill was stratified into two domains: gross motoric and fine motoric. Behavioral problem was categorized as externalizing and internalizing behavior.

RESULTS

Meta-analysis showed that verbal intelligence score in IVF toddlers is significantly lower than NC toddlers (p = 0.02); conversely, ICSI toddlers scored significantly higher verbal intelligence score compared to NC toddlers (p = 0.005). Toddlers born after ART had significantly lower non-verbal intelligence score (p = 0.047). IVF toddlers scored significantly lower fine motor score (p = 0.01) compared to naturally conceived toddlers. Based on parent's CBCL, NC toddlers had higher total (p = 0.01) and externalizing behavior (p = 0.001) scores  compared to ART toddlers. Evaluation of full scale IQ and all domains of intelligence in preschool and primary school children revealed that no significant differences exist between ART and NC children. Based on preschool and primary school parents' CBCL, IVF children had significantly lower externalizing behavior score compared to NC children (p = 0.04). Meta-analyses of studies on young adolescents revealed that ART young adolescents scored higher academically than their NC counterparts, including on mathematics (p < 0.00001) and reading or language (p < 0.00001).

CONCLUSIONS

Despite differences in certain aspects, this finding suggests that ART is unlikely to cause negative impacts on children's neurodevelopment.

Examining attention-deficit/hyperactivity disorder and related behavioral disorders by fertility treatment exposure in a prospective cohort

PURPOSE

To evaluate whether underlying infertility and mode of conception are associated with childhood behavioral disorders.

METHODS

Oversampling on fertility treatment exposure using vital records, the Upstate KIDS Study followed 2057 children (of 1754 mothers) from birth to 11 years. Type of fertility treatment and time to pregnancy (TTP) were self-reported. Mothers completed annual questionnaires reporting symptomology, diagnoses, and medications at 7-11 years of age. The information identified children with probable attention-deficit/hyperactivity disorder, anxiety or depression, and conduct or oppositional defiant disorders. We estimated adjusted relative risks (aRR) for disorders by underlying infertility (TTP > 12 months) or treatment exposure groups compared to children born to parents with TTP ≤ 12 months.

RESULTS

Children conceived with fertility treatment (34%) did not have an increased risk of attention-deficit/hyperactivity disorder (aRR): 1.21; 95% CI: 0.88, 1.65), or conduct or oppositional defiant disorders (aRR: 1.31; 0.91, 1.86), but did have an increased risk of anxiety or depression (aRR: 1.63; 1.18, 2.24), which remained elevated even after adjusting for parental mood disorders (aRR: 1.40; 0.99, 1.96). Underlying infertility without the use of treatment was also associated with a risk of anxiety or depression (aRR: 1.82; 95% CI: 0.96, 3.43).

CONCLUSIONS

Underlying infertility or its treatment was not associated with risk of attention-deficit/hyperactivity disorder. Observations of increased anxiety or depression require replication.

Neurodevelopmental Outcomes of Pregnancies Resulting from Assisted Reproduction: A Review of the Literature

The term infertility is defined as the lack of conception within 1 year of unprotected intercourse. It affects more than 80 million individuals worldwide. It is estimated that 10-15% of couples of reproductive age are challenged by reproductive issues. Assisted reproduction techniques (ART) are responsible for more than 4% of live births. Our aim is to review the research on neurodevelopmental outcomes of newborns born after the implementation of assisted reproduction methods compared to those conceived naturally. We conducted a comprehensive search of the PubMed, Crossref and Google Scholar electronic databases for related articles up to June 2022 using the PRISMA guidelines. Our research revealed a large number of long term follow-up studies between 2 and 18 years of age, with comparable developmental outcomes. Many studies compared the effects of different infertility treatments against natural conception. The review of the literature revealed that ART is safe, as the majority of studies showed no effect on the neurodevelopmental outcomes of the offspring. In most cases when such an effect was observed, it could be attributed to confounding factors such as subfertility, multiple pregnancies and gestational age at delivery. Finally, the increase in the prevalence of neurodevelopmental disorders after ART, as described in studies with statistically significant results, is predominantly marginal, and given the low incidence of neurodevelopmental disorders in the general population, its clinical significance is debatable.

Attention-deficit hyperactivity disorder in children born to mothers with infertility: a population-based cohort study

STUDY QUESTION

Is the risk of attention-deficit hyperactivity disorder (ADHD) increased in children born to mothers with infertility, or after receipt of fertility treatment, compared to mothers with unassisted conception?

SUMMARY ANSWER

Infertility itself may be associated with ADHD in the offspring, which is not amplified by the use of fertility treatment.

WHAT IS KNOWN ALREADY

Infertility, and use of fertility treatment, is common. The long-term neurodevelopmental outcome of a child born to a mother with infertility, including the risk of ADHD, remains unclear.

STUDY DESIGN, SIZE, DURATION

This population-based cohort study comprised all singleton and multiple hospital births in Ontario, Canada, 2006–2014. Outcomes were assessed up to June 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Linked administrative datasets were used to capture all hospital births in Ontario, maternal health and pregnancy measures, fertility treatment and child outcomes. Included were all children born at ≥24 weeks gestation between 2006 and 2014, and who were alive at age 4 years. The main exposure was mode of conception, namely (i) unassisted conception (reference group), (ii) infertility without fertility treatment (history of an infertility consultation with a physician within 2 years prior to conception but no fertility treatment), (iii) ovulation induction (OI) or intrauterine insemination (IUI) and (iv) IVF or intracytoplasmic sperm injection (ICSI). The main outcome was a diagnosis of ADHD after age 4 years and assessed up to June 2020. Hazard ratios (HRs) were adjusted for maternal age, income quintile, rurality, immigration status, smoking, obesity, parity, any drug or alcohol use, maternal history of mental illness including ADHD, pre-pregnancy diabetes mellitus or chronic hypertension and infant sex. In addition, we performed pre-planned stratified analyses by mode of delivery (vaginal or caesarean delivery), infant sex, multiplicity (singleton or multiple), timing of birth (term or preterm <37 weeks) and neonatal adverse morbidity (absent or present).

MAIN RESULTS AND THE ROLE OF CHANCE

The study included 925 488 children born to 663 144 mothers, of whom 805 748 (87%) were from an unassisted conception, 94 206 (10.2%) followed infertility but no fertility treatment, 11 777 (1.3%) followed OI/IUI and 13 757 (1.5%) followed IVF/ICSI. Starting at age 4 years, children were followed for a median (interquartile range) of 6 (4–8) years. ADHD occurred among 7.0% of offspring in the unassisted conception group, 7.5% in the infertility without fertility treatment group, 6.8% in the OI/IUI group and 6.3% in the IVF/ICSI group. The incidence rate (per 1000 person-years) of ADHD was 12.0 among children in the unassisted conception group, 12.8 in the infertility without fertility treatment group, 12.9 in the OI/IUI group and 12.2 in the IVF/ICSI group. Relative to the unassisted conception group, the adjusted HR for ADHD was 1.19 (95% CI 1.16–1.22) in the infertility without fertility treatment group, 1.09 (95% CI 1.01–1.17) in the OI/IUI group and 1.12 (95% CI 1.04–1.20) in the IVF/ICSI group. In the stratified analyses, these patterns of risk for ADHD were largely preserved. An exception was seen in the sex-stratified analyses, wherein females had lower absolute rates of ADHD but relatively higher HRs compared with that seen among males.

LIMITATIONS, REASONS FOR CAUTION

Some mothers in the isolated infertility group may have received undocumented OI oral therapy, thereby leading to possible misclassification of their exposure status. Parenting behaviour, schooling and paternal mental health measures were not known, leading to potential residual confounding.

WIDER IMPLICATIONS OF THE FINDINGS

Infertility, even without treatment, is a modest risk factor for the development of ADHD in childhood. The reason underlying this finding warrants further study.

STUDY FUNDING/COMPETING INTEREST(s)

This study was made possible with funding from the Canadian Institutes of Health Research, Grant number PJT 165840. The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Association between intracytoplasmic sperm injection and neurodevelopmental outcomes among offspring

PURPOSE

To compare the risk of neurodevelopmental disorders in children conceived via intracytoplasmic sperm injection (ICSI) and those conceived naturally.

MATERIALS AND METHODS

A population-based cohort study using data retrieved from the Taipei Medical University Research Database (TMURD) from January, 2004 to August, 2016. The data included maternal pregnancy history, perinatal history and developmental follow up of their babies up to 5 years of age. The study included 23885 children, of whom 23148 were naturally conceived and 737 were conceived via ICSI. Neurodevelopmental disorders defined by 21 ICD-9-CM codes.

RESULTS

Of the 23885 children enrolled for analysis, 2778 children were included for further subgrouping analysis after propensity matching to reduce bias from maternal factors. The single-birth group included 1752 naturally conceived (NC) children and 438 ICSI children. The multiple-birth group included 294 NC and 294 ICSI children. The risk of neurodevelopmental disorders was not increased for ICSI children in both groups (single birth: adjusted hazard ratio aHR = 0.70, 95% CI = 0.39-1.27, p = 0.243; multiple-birth group aHR = 0.77, 95% CI = 0.43-1.35, p = 0.853). In the single-birth group, multivariate analyses showed that male sex (aHR = 1.81, 95% CI = 1.29-2.54, p < 0.001), and intensive care unit (ICU) admission (aHR = 3.10, 95% CI = 1.64-5.86, p < 0.001) were risk factors for neurodevelopmental disorders. In the multiple-birth group, multivariate analyses demonstrated that ICU admission (aHR = 3.58, 95% CI = 1.82-7.04, p < 0.001), was risk factor for neurodevelopmental disorders.

CONCLUSION

Our study indicated that the use of ICSI does not associated with higher risk of neurodevelopmental disorders in the offspring. But male sex, and ICU admission do have increased risk of neurodevelopmental disorders. However, long term follow up of this cohort on health outcomes in adolescence and adulthood will strengthen the conclusions that ICSI is safe regarding offspring long term outcome.

Cognitive achievements in school-age children born following assisted reproductive technology treatments: A prospective study

BACKGROUND

While assisted reproductive technology is increasingly prevalent, there is concern amid conflicting findings reported regarding the long-term outcomes of children born following these treatments. The aim of this research was to investigate aspects of cognitive development in early school-age Israeli children born following assisted reproductive technology (ART) treatments, compared to those spontaneously conceived (SC).

METHOD

This prospective follow-up study was based on an Israeli cohort recruited from June 2006 to December 2008, that included 561 women whose pregnancies were achieved by ART treatments and 600 women whose pregnancies were SC. When the children were 7-8 years old, 759 of their mothers were interviewed by telephone, and 294 were came for developmental assessment. The examination included: Kaufman Brief Intelligence Test; Kaufman Assessment Battery for Children (arithmetic only); Test of Everyday Attention for Children; Beery-Buktenica Developmental Test of Visual-Motor Integration and Supplemental Test for Visual Perception; Rey-Osterrieth Complex Figure Test; Aleph-ad-Tav Hebrew reading and writing; Tavor Picture Naming Expressive Vocabulary Test. Multivariable analyses were adjusted for maternal years of education (≤12, 13+) at child's birth and child's sex.

RESULTS

Cognitive function, visual-motor ability, attention, and verbal skills of children born after ART treatments were similar to those of SC children, upon both univariate and multivariable analysis.

CONCLUSION AND IMPLICATIONS

No significant differences were found between the ART and SC groups on any of the measures examined. This finding offers couples seeking ART treatments improved information regarding child development during the important and formative school years.

WHAT THIS PAPER ADDS

Increasing rates of ART treatments arouse concern about long-term outcomes for offspring, and conflicting findings have been reported with respect to the skills necessary to their academic success. This prospective follow-up study compared school-age children born following ART with spontaneously-conceived children. Children were examined by developmental psychologists, and cognitive function, visual-motor, attention, verbal, and performance skills were similar in both groups.

Cognitive and behavioural outcome of children born after IVF at age 9 years

STUDY QUESTION

Do ovarian stimulation (OS) and the in vitro laboratory procedures affect offsprings' cognitive and behavioural outcome at 9 years?

SUMMARY ANSWER

OS and the in vitro laboratory procedures or the combination of both were not associated with cognitive and behavioural outcome at age 9 years.

WHAT IS KNOWN ALREADY

ART is not associated with an adverse short-term developmental outcome of the offspring, but limited knowledge is available on the offspring's long-term neurodevelopmental condition.

STUDY DESIGN, SIZE, DURATION

A 9-year longitudinal, assessor-blinded, prospective follow-up study of 169 out of 215 singletons (79%) born between March 2005 and December 2006 was performed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Singletons born following IVF or ICSI with OS (n = 57), born after modified natural cycle IVF/ICSI (MNC-IVF/ICSI; n = 46) and born after natural conception to subfertile couples (Sub-NC; n = 66), were assessed at 9 years. This study design, with two ART groups and a subfertile reference group, allows for disentangling the effects of OS and ART procedures on developmental outcome. Cognitive outcome was evaluated with the Wechsler abbreviated scale of intelligence and the NEPSY-II. Behaviour was assessed with the child behaviour checklist (CBCL) and teacher report form (TRF). Univariable analyses and multiple linear regression models were used.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no significant difference in intelligence quotient (IQ) scores between ART groups (mean IQ (95% CI): OS 114.8 (83.2-142.6); MNC 114.0 (90.2-140.8); Sub-NC 115.4 (87.9-141.2), P = 0.746). Multivariable analyses did not reveal a statistically significant association between ART group and total, verbal and performance IQ. CBCL and TRF scores did not differ significantly between ART groups (P = 0.090 and 0.507, respectively). Multivariable analyses did not demonstrate a statistically significant association between ART group and CBCL and TRF total, or internalising and externalising T-scores. No significant correlations between time to pregnancy (TTP)-a proxy for the severity of parental subfertility-and outcome measures were found (Spearman rho between -0.050 and 0.049, NS), which was confirmed with multivariable analyses.

LIMITATIONS, REASONS FOR CAUTION

The attrition rate of 21% may be considered as a limitation of the study; however, after a follow-up period of 9 years, this rate is generally considered acceptable, and there were no significant differences in background characteristics between children with and without follow-up, making an attrition-related selection bias less likely. Another limitation of the study is the relatively small sample size, which could contribute to selection bias, hamper generalizability to the ART population and lead to false negative findings as a result of underpowering. An a priori power analysis on total IQ indicated that the OS-IVF/ICSI and Sub-NC groups should contain 64 children, confirming that our study including 57 and 66 children, respectively, was slightly underpowered.

WIDER IMPLICATIONS OF THE FINDINGS

Our study indicated that OS and the in vitro laboratory procedures or the combination of both and TTP were not associated with cognitive and behavioural outcome at 9 years. These are reassuring results for both parents and clinicians involved in ART.

STUDY FUNDING/COMPETING INTEREST(S)

The study was financially supported by the University Medical Center Groningen (UMCG), two graduate schools of the UMCG (BCN and SHARE) and the Cornelia Stichting. The sponsors of the study had no role in study design, data collection, data analysis, data interpretation or writing of the report. The authors have no conflicts of interest to declare.

The impact of specific fertility treatments on cognitive development in childhood and adolescence: a systematic review

STUDY QUESTION

Does fertility treatment influence cognitive ability in school aged children, and does the impact vary with the type of treatment?

SUMMARY ANSWER

The available high-quality evidence indicates that specific treatments may give rise to different effects on cognitive development, with certain treatments, including ICSI, associated with cognitive impairment.

WHAT IS KNOWN ALREADY

Previous reviews of the literature concerning cognitive outcomes among children conceived with medical assistance have concluded that study findings are generally 'reassuring', but limited attention has been paid to the quality of this research. In addition, no review has separately assessed the range of treatment modalities available, which vary in invasiveness, and thus, potentially, in their effects on developmental outcomes.

STUDY DESIGN, SIZE, DURATION

A systematic review was undertaken. We searched PubMed, PsycINFO and the Educational Resources Information Centre database to identify English-language studies published up until 21 November 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Two authors independently reviewed identified articles, extracted data and assessed study quality. Studies were eligible if they assessed cognitive development from age 4 years or more, among children conceived with fertility treatment compared with either children conceived naturally or children born from a different type of fertility treatment. Where available, data were extracted and reported separately according to the various components of treatment (e.g. mode of fertilization, embryo freezing, etc.). Risk of bias was assessed using the Newcastle-Ottawa Scale, with a score ≥7/9 indicative of high quality.

MAIN RESULTS AND THE ROLE OF CHANCE

The search identified 861 articles, of which 35 were included. Of these, seven were rated high quality. Most studies (n = 22) were subject to selection bias, due to the exclusion of children at increased risk of cognitive impairment. Among high-quality studies, there was no difference in cognitive outcomes among children conceived with conventional IVF and those conceived naturally. Findings among high-quality studies of children conceived with ICSI were inconsistent: when compared with children conceived naturally, one study reported lower intelligence quotient (IQ; 5-7 points, on average) among ICSI children whereas the remaining two high-quality studies reported no difference between groups. Furthermore, among the three high-quality studies comparing children conceived with ICSI compared with conventional IVF, one reported a significant increase in the risk of mental retardation, one reported a small difference in IQ (3 points lower, on average) and one no difference at all. There were scant studies examining exposure to embryo freezing, or less invasive treatments such as ovulation induction without IVF/ICSI.

LIMITATION, REASONS FOR CAUTION

Most existing studies had methodological limitations including selection bias and/or failure to address confounding by family background. In addition, a meta-analysis could not be performed due to heterogeneity in the assessment of cognitive outcomes. These factors impeded our ability to synthesize the evidence and draw reliable conclusions.

WIDER IMPLICATIONS OF THE FINDINGS

The conflicting findings among studies of children conceived with ICSI require clarification, in light of the increasing use of this technique for reasons other than male-factor infertility. Further population-based studies are needed that utilize contemporary data to examine specific aspects of treatment and combinations of techniques (e.g. ICSI with frozen embryo cycles). Importantly, studies should include the complete group of children exposed to treatment.

STUDY FUNDING/COMPETING INTEREST(S)

A.R.R. is supported by a Career Development Fellowship from the National Health and Medical Research Council of Australia. L.J.M. is funded by a fellowship from the Heart Foundation of Australia. The authors declare there are no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

Academic performance in adolescents born after ART-a nationwide registry-based cohort study

STUDY QUESTION

Is academic performance in adolescents aged 15-16 years and conceived after ART, measured as test scores in ninth grade, comparable to that for spontaneously conceived (SC) adolescents?

SUMMARY ANSWER

ART singletons had a significantly lower mean test score in the adjusted analysis when compared with SC singletons, yet the differences were small and probably not of clinical relevance.

WHAT IS KNOWN ALREADY

Previous studies have shown similar intelligence quotient (IQ) levels in ART and SC children, but only a few have been on adolescents. Academic performance measured with standardized national tests has not previously been explored in a complete national cohort of adolescents conceived after ART.

STUDY DESIGN, SIZE, DURATION

A Danish national registry-based cohort including all 4766 ART adolescents (n = 2836 singletons and n = 1930 twins) born in 1995-1998 were compared with two SC control cohorts: a randomly selected singleton population (n = 5660) and all twins (n = 7064) born from 1995 to 1998 in Denmark. Nine children who died during the follow-up period were excluded from the study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mean test scores on a 7-point-marking scale from -3 to 12 were compared, and adjustments were made for relevant reproductive and socio-demographic covariates including occupational and educational level of the parents.

MAIN RESULTS AND THE ROLE OF CHANCE

The crude mean test score was higher in both ART singletons and ART twins compared with SC adolescents. The crude mean differences were +0.41 (95% CI 0.30-0.53) and +0.45 (95% CI 0.28-0.62) between ART and SC singletons and between ART and SC twins, respectively. However, the adjusted mean overall test score was significantly lower for ART singletons compared with SC singletons (adjusted mean difference -0.15 (95% CI -0.29-(-0.02))). For comparison, the adjusted mean difference was +2.05 (95% CI 1.82-2.28) between the highest and the lowest parental educational level, suggesting that the effect of ART is weak compared with the conventional predictors. The adjusted analyses showed significantly lower mean test scores in mathematics and physics/chemistry for ART singletons compared with SC singletons. Comparing ART twins with SC twins yielded no difference in academic performance in the adjusted analyses. Similar crude and adjusted overall mean test scores were found when comparing ART singletons and ART twins.

LIMITATIONS, REASONS FOR CAUTION

Missing data on educational test scores occurred in 6.6% of adolescents aged 15-16 years for the birth cohorts 1995-1997, where all of the children according to their age should have passed the ninth grade exam at the time of data retrieval. As sensitivity analyses yielded no significant difference in the adjusted risk of having missing test scores between any of the groups, it is unlikely that this should bias our results. Adjustment for body mass index and smoking during pregnancy was not possible.

WIDER IMPLICATIONS OF THE FINDINGS

As our results are based on national data, our findings can be applied to other populations. The findings of this paper suggest that a possible small negative effect of parental subfertility or ART treatment is counterbalanced by the higher educational level in the ART parents.

STUDY FUNDING/COMPETING INTERESTS

The Danish Medical Association in Copenhagen (KMS) funded this study with a scholarship grant. None of the authors had any competing interests.

TRIAL REGISTRATION NO STATISTICS DENMARK

704676.

Long-awaited pregnancy: intelligence and academic performance in offspring of infertile parents-a cohort study

OBJECTIVE

To study whether fertility treatment, subfertility, or pregnancy planning are related to long-term intellectual development.

DESIGN

Cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 5,032 singletons born from 1990 to 1992 in the Aarhus Birth Cohort were followed up to a mean age of 19 years. These children were born as a result of fertility treatment (n = 210), had subfertile parents who took more than 12 months before conceiving naturally (n = 334), had fertile parents who conceived naturally within 12 months (n = 2,661), or had parents who reported the pregnancy as unplanned (n = 1,827).

INTERVENTION(S)

The children were followed up using questionnaires and information from Danish national registers.

MAIN OUTCOME MEASURE(S)

Parent reported school difficulties at ages 9-11 years, register-based school grades at ages 16, 17, and 19 years, and conscription intelligence test scores at age 19 years.

RESULT(S)

We found no evidence of school difficulties in childhood, impaired school performance in adolescence, or lower intelligence in young adulthood in multivariate analyses adjusted for parental age, educational level, maternal parity, before pregnancy body mass index (BMI), smoking and alcohol intake in pregnancy, cohabitation status, child gender, and age.

CONCLUSION(S)

In the longest follow-up of cognitive development of children conceived after fertility treatment or by subfertile parents conducted so far, this study did not show any association between pregnancy planning, subfertility, or fertility treatment and cognitive ability or academic performance.

Multifactorial determinants of cognition - Thyroid function is not the only one

Background

Since the 1960s hypothyroidism together with iodine deficiency have been considered to be a principal determinant of cognition development. Following iodine supplementation programs and improved treatment options for hypothyroidism this relation might not be valid in 2015. On the other hand neurosciences have added different inputs also related to cognition.

Scope of review

We will examine the characteristics of the original and current publications on thyroid function and cognition and also add some general determinants of intelligence and cognition. One central issue for us is the relation of stress to cognition knowing that both physical and psychological stress, are frequent elements in subjects with thyroid dysfunction. We have considered a special type of stress called pre-natal stress which can influence cognitive functions. Fear and anxiety can be intermingled requiring mechanisms of fear extinction.

Major conclusions

Recent studies have failed to show an influence of thyroid medication during pregnancy on intellectual development. Neuroscience offers a better explanation of cognition than hypothyroidism and iodine deficiency. Additional factors relevant to cognition are nutrition, infection, prenatal stress, and early life stress. In turn stress is related to low magnesium levels. Magnesium supplementation can correct both latent hypothyroidism and acquired mild cognitive deficits.

General significance

Cognition is a complex process that depends on many determinants and not only on thyroid function. Magnesium deficiency appears to be a basic mechanism for changes in thyroid function as well as of cognition.

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Untreated hypothyroidism, i.e. hypothyroxinemia, can influence IQ.

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Thyroxine administration to euthyroid pregnant women has no effect on cognition.

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The hippocampus and NMDA receptors play a central role in cognitive processes.

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Antenatal and early life stressors can influence cognition later in life.

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Stressors can lead to decreased levels of magnesium and demands supplementation.