DNA methylation differences at birth after conception through ART.

STUDY QUESTION: Is there a relation between ART and DNA methylation (DNAm) patterns in cord blood, including any differences between IVF and ICSI? SUMMARY ANSWER: DNAm at 19 CpGs was associated with conception via ART, with no difference found between IVF and ICSI. WHAT IS KNOWN ALREADY: Prior studies on either IVF or ICSI show conflicting outcomes, as both widespread effects on DNAm and highly localized associations have been reported. No study on both IVF and ICSI and genome-wide neonatal DNAm has been performed. STUDY DESIGN, SIZE, DURATION: This was a cross-sectional study comprising 87 infants conceived with IVF or ICSI and 70 conceived following medically unassisted conception. The requirement for inclusion in the study was an understanding of the Swedish language and exclusion was the use of donor gametes. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were from the UppstART study, which was recruited from fertility and reproductive health clinics, and the Born into Life cohort, which is recruited from the larger LifeGene study. We measured DNAm from DNA extracted from cord blood collected at birth using a micro-array (450k array). Group differences in DNAm at individual CpG dinucleotides (CpGs) were determined using robust linear models and post-hoc Tukey's tests. MAIN RESULTS AND THE ROLE OF CHANCE: We found no association of ART conception with global methylation levels, imprinted loci and meta-stable epialleles. In contrast, we identify 19 CpGs at which DNAm was associated with being conceived via ART (effect estimates: 0.5-4.9%, PFDR < 0.05), but no difference was found between IVF and ICSI. The associated CpGs map to genes related to brain function/development or genes connected to the plethora of conditions linked to subfertility, but functional annotation did not point to any likely functional consequences. LIMITATIONS, REASONS FOR CAUTION: We measured DNAm in cord blood and not at later ages or in other tissues. Given the number of tests performed, our study power is limited and the findings need to be replicated in an independent study. WIDER IMPLICATIONS OF THE FINDINGS: We find that ART is associated with DNAm differences in cord blood when compared to non-ART samples, but these differences are limited in number and effect size and have unknown functional consequences in adult blood. We did not find indications of differences between IVF and ICSI. STUDY FUNDING/COMPETING INTEREST(S): E.W.T. was supported by a VENI grant from the Netherlands Organization for Scientific Research (91617128) and JPI-H2020 Joint Programming Initiative a Healthy Diet for a Healthy Life (JPI HDHL) under proposal number 655 (PREcisE Project) through ZonMw (529051023). Financial support was provided from the European Union's Seventh Framework Program IDEAL (259679), the Swedish Research Council (K2011-69X-21871-01-6, 2011-3060, 2015-02434 and 2018-02640) and the Strategic Research Program in Epidemiology Young Scholar Awards, Karolinska Institute (to A.N.I.) and through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Strategic Research Program in Epidemiology at Karolinska Institutet and the Swedish Heart-Lung Foundation and Danderyd University Hospital (Stockholm, Sweden). The funders had no role in study design, data collection, analysis, decision to publish or preparation of the manuscript. The authors declare no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Pediatric use of prescribed melatonin in Sweden 2006-2017: a register based study.

Sleep disturbances are common in the pediatric population and should primarily be treated non-pharmacologically. Most medicines for sleep disturbances are not approved for pediatric use and data on long-term safety is scarce. In Sweden, melatonin is classified as a prescription medicine. The aim of the present study was to characterize the prevalence and incidence of dispensed melatonin prescriptions, long-term treatment, concomitant dispensation of psychotropic medication, and psychiatric comorbidity, in children and adolescents aged 0-17 years living in Sweden during 2006-2017. Data was retrieved by linking the national population-based registers, the Swedish Prescribed Drug register and the National Patient register. In 2017, nearly 2% of the pediatric population 0-17 years was dispensed at least one prescription of melatonin, which was more than a 15-fold increase for girls and a 20-fold increase for boys, when compared to 2006. Among the children in the age group 5-9 who initiated a melatonin treatment in 2009, 15% of girls and 17% of boys were found to be continuously prescribed melatonin 8 years later. Nearly 80% of all children with dispensed melatonin had concomitant dispensations of psychotropic medications. The most common combination was melatonin together with centrally acting sympathomimetic medicines (23% of girls and 43% of boys). About half of the children (47% of girls and 50% of boys) had at least one registered diagnosis of mental or behavioral disorders. The most common diagnosis was attention deficit hyperactive disorder, across all age groups and genders. The continuous increase of use of melatonin in children, often concomitant with other psychotropic medications, together with a high proportion of younger children with prescriptions of melatonin on a long-term basis, suggests the need for further structured follow up studies, in particular of long-term use.

Assisted reproductive technology and risk of ovarian cancer and borderline tumors in parous women: a population-based cohort study.

The study aimed to investigate if assisted reproductive technology (ART) treatment or a diagnosis of infertility were associated with the risk of ovarian cancer or borderline ovarian tumors (BOT) in parous women. In a population-based register study of 1,340,097 women with a first live birth in Sweden 1982-2012, the relationship between ART treatments, infertility and incidence of ovarian cancer or BOT were investigated using Cox regression analysis. In the cohort, 38,025 women gave birth following ART, 49,208 following an infertility diagnosis but no ART and 1,252,864 without infertility diagnosis or ART. During follow-up, 991 women were diagnosed with ovarian cancer and 747 with BOT. Women who gave birth following ART had higher incidence of both ovarian cancer (adjusted hazard ratio [aHR] 2.43, 95% confidence interval [CI] 1.73-3.42) and BOT (aHR 1.91, 95% CI 1.27-2.86), compared to women without infertility. Compared to women with infertility diagnoses and non-ART births, women with ART births also had a higher incidence of ovarian cancer (aHR 1.79, 95% CI 1.18-2.71) and BOT (aHR 1.48, 95% CI 0.90-2.44). Our results suggest that women who have gone through ART have a higher risk of ovarian cancer and BOT. At least part of that risk seems to be due to the underlying infertility and not the treatment per se, since the increased risk was smaller when comparing to other infertile women. As ART treatments are becoming more common and ovarian cancer usually occur in women of advanced age, larger studies with longer follow-up are needed in order to confirm or refute our findings.

The risk of breast and gynecological cancer in women with a diagnosis of infertility: a nationwide population-based study.

Some studies have suggested that infertility is a risk factor for endometrial, ovarian and breast cancer. The study aimed to create a comprehensive picture of the association between infertility and the risk of ovarian, endometrial and breast cancer, and whether any association could be explained by ovulatory disturbances, endometriosis or nulliparity. In a population-based cohort of 2,882,847 women, cox regression analysis was used to investigate cancer incidence among infertile women. Overall, infertility was associated with a higher incidence rate of ovarian (adjusted hazard ratio [aHR] 1.53, 95% confidence interval [CI] 1.38-1.71) and endometrial cancer (aHR 1.25, 95% CI 1.11-1.40), but not of breast cancer (aHR 0.96, 95% CI 0.92-1.01). Ovarian cancer incidence was higher in women diagnosed with endometriosis, and in nulliparous women with ovulatory disturbances, compared to women with none of the diagnoses. Endometrial cancer incidence was higher in women with ovulatory disturbances, but not in women with endometriosis. These findings suggest that infertility could have long-term consequences of importance to physicians and public health workers.

Association of infertility and fertility treatment with mammographic density in a large screening-based cohort of women: a cross-sectional study.

BACKGROUND: Ovarian stimulation drugs, in particular hormonal agents used for controlled ovarian stimulation (COS) required to perform in vitro fertilization, increase estrogen and progesterone levels and have therefore been suspected to influence breast cancer risk. This study aims to investigate whether infertility and hormonal fertility treatment influences mammographic density, a strong hormone-responsive risk factor for breast cancer. METHODS: Cross-sectional study including 43,313 women recruited to the Karolinska Mammography Project between 2010 and 2013. Among women who reported having had infertility, 1576 had gone through COS, 1429 had had hormonal stimulation without COS and 5958 had not received any hormonal fertility treatment. Percent and absolute mammographic densities were obtained using the volumetric method Volpara™. Associations with mammographic density were assessed using multivariable generalized linear models, estimating mean differences (MD) with 95 % confidence intervals (CI). RESULTS: After multivariable adjustment, women with a history of infertility had 1.53 cm(3) higher absolute dense volume compared to non-infertile women (95 % CI: 0.70 to 2.35). Among infertile women, only those who had gone through COS treatment had a higher absolute dense volume than those who had not received any hormone treatment (adjusted MD 3.22, 95 % CI: 1.10 to 5.33). No clear associations were observed between infertility, fertility treatment and percent volumetric density. CONCLUSIONS: Overall, women reporting infertility had more dense tissue in the breast. The higher absolute dense volume in women treated with COS may indicate a treatment effect, although part of the association might also be due to the underlying infertility. Continued monitoring of cancer risk in infertile women, especially those who undergo COS, is warranted.

Somatic Comorbidity in Women with Overactive Bladder Syndrome.

PURPOSE: We explore the influence of co-occurring somatic illnesses on prevalent overactive bladder in women of premenopausal age. MATERIALS AND METHODS: Data for the present study were derived from a nationwide survey on complex diseases among all twins in the Swedish Twin Registry born 1959 to 1985. The present study was limited to female twins participating in the survey (12,850). Generalized estimating equations were used to estimate odds ratios with 95% CIs. Environmental and genetic influences were assessed in co-twin control analysis. RESULTS: Generalized estimating equations analysis showed a significant association between overactive bladder and migraine (OR 1.34, 95% CI 1.15-1.57), fibromyalgia (1.83, 1.54-2.18), chronic fatigue (1.81, 1.49-2.19) and eating disorders (1.56, 1.24-1.96). There was also a significant association with allergic disorders including asthma (1.24, 1.01-1.52) and eczema (1.22, 1.04-1.43). Among reproductive disorders, urinary tract infections (1.60, 1.40-1.84), dysmenorrhea (1.53, 1.33-1.76) and pelvic pain (1.60, 1.31-1.94) showed the strongest association with overactive bladder. Results from co-twin control analysis indicated that the significant associations observed in generalized estimating equations analysis were influenced by environmental and genetic factors without a common pathway model. CONCLUSIONS: Our results suggest a multifactorial and complex pathogenesis of overactive bladder in which associations between various somatic illnesses and overactive bladder may be affected by environmental and genetic factors.

Risk for childhood leukemia associated with maternal and paternal age.

The role of reproductive factors, such as parental age, in the pathogenesis of childhood leukemias is being intensively examined; the results of individual studies are controversial. This meta-analysis aims to quantitatively synthesize the published data on the association between parental age and risk of two major distinct childhood leukemia types in the offspring. Eligible studies were identified and pooled relative risk (RR) estimates were calculated using random-effects models, separately for childhood acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Subgroup analyses were performed by study design, geographical region, adjustment factors; sensitivity analyses and meta-regression analyses were also undertaken. 77 studies (69 case-control and eight cohort) were deemed eligible. Older maternal and paternal age were associated with increased risk for childhood ALL (pooled RR = 1.05, 95 % CI 1.01-1.10; pooled RR = 1.04, 95 % CI 1.00-1.08, per 5 year increments, respectively). The association between maternal age and risk of childhood AML showed a U-shaped pattern, with symmetrically associated increased risk in the oldest (pooled RR = 1.23, 95 % CI 1.06-1.43) and the youngest (pooled RR = 1.23, 95 % CI 1.07-1.40) extremes. Lastly, only younger fathers were at increased risk of having a child with AML (pooled RR = 1.28, 95 % CI 1.04-1.59). In conclusion, maternal and paternal age represents a meaningful risk factor for childhood leukemia, albeit of different effect size by leukemia subtype. Genetic and socio-economic factors may underlie the observed associations. Well-adjusted studies, scheduled by large consortia, are anticipated to satisfactorily address methodological issues, whereas the potential underlying genetic mechanisms should be elucidated by basic research studies.

Does urinary incontinence have fetal origins? Results from a nationwide twin study.

INTRODUCTION AND HYPOTHESIS: The aim of this study is to evaluate the effect of birth weight and being born small for gestational age (SGA) on urinary incontinence (UI) among premenopausal women. METHODS: In 2005, a total of 14,094 female twins born 1959-1985 who had been included in the Swedish Twin Registry participated in a survey on common exposures and complex diseases, including urinary incontinence. Information regarding birth weight and gestational age was obtained from the Medical Birth Register (for twins born 1973-1985) and from the medical archives (for twins born 1959-1972). A logistic regression model based on generalized estimating equations was used to estimate odds ratios (ORs) with 95 % confidence intervals (CIs). RESULTS: In both crude and adjusted analysis, birth weight and SGA had no effect on UI. An interaction between low birth weight (<2,500 g) and body mass index (BMI) later in life was found for overall and stress UI. Compared with women who were not overweight and had a birth weight above 2,500 g, overweight women (BMI ≥ 25) who had a normal birth weight had a 35 % higher odds of incontinence , while overweight women who had a low birth weight had an approximately 85 % higher odds of UI (OR = 1.84, 95 % CI 1.39-2.45 for overall UI; OR = 1.83, 95 % CI 1.35-2.48 for stress UI). CONCLUSIONS: Birth weight and SGA had no direct effect on urinary incontinence; however, low birth weight in combination with an elevated adult BMI may contribute to the risk of urinary incontinence later in life.

Maternal and fetal genetic contributions to postterm birth: familial clustering in a population-based sample of 475,429 Swedish births.

This study examines the familial clustering and relative influence of genetic and environmental effects on postterm birth in the Swedish population by considering all full- and half-siblings born in Sweden between 1992 and 2004. Of the eligible 475,429 births, 21% occurred after 41 completed weeks and 5.5% occurred after 42 completed weeks of gestation. Odds of postterm birth increased if mothers were older, heavier, more educated, primiparous, or carrying a male fetus. The highest odds increase was seen in women with a previous postterm birth, both with the same partner (odds ratio = 4.4, 95% confidence interval: 4.0, 4.6) and after a partner change (odds ratio = 3.4, 95% confidence interval: 2.9, 3.9). Sisters of women with a postterm birth were also at increased odds of postterm birth (odds ratio = 1.8, 95% confidence interval: 1.6, 2.0) while brothers' partners were not. Half of the variation in postterm birth could not be explained by factors shared in families, and the remaining half was explained by genetic factors, namely fetal (26%) and maternal (21%) genetic factors. Familial clustering of postterm birth is attributed to genetic effects, and fetal genetic effects have a considerable influence on the liability of postterm birth.

Depression, neuroticism, and urinary incontinence in premenopausal women: a nationwide twin study.

Previous studies have found that major depression and neuroticism are positively associated with urinary incontinence (UI). However, the genetic contribution to these associations has never been investigated. In 2005, a total of 14,094 female twins born 1959-1985 in the Swedish Twin Registry participated in a comprehensive survey on common exposures and complex diseases. Structured questions provided information on UI, depressive symptoms, major depression, and neuroticism. A logistic regression model based on generalized estimating equations (GEE) was used to estimate odds ratios (ORs) with 95% confidence intervals (CIs). Environmental and genetic influences were assessed in co-twin control analyses and quantitative genetic analyses, which were also used to determine the proportion of the phenotypic correlation explained by familial factors. Major depression, depressive symptoms, and neuroticism were positively associated with all UI subtypes (overall, stress, urge, and mixed UI). In a trivariate Cholesky model with neuroticism, depressive symptoms (or depression), and UI a modest genetic correlation was found between indicators of depression and overall, or stress, UI. The majority of this correlation was independent from neuroticism. In contrast, the genetic factors shared between indicators of depression and urge or mixed UI were entirely in common with neuroticism. In conclusion, depression and neuroticism are associated with UI among premenopausal women: the associations are in part determined by genetic factors in common to the disorders.

Birth weight predicts risk of cardiovascular disease within dizygotic but not monozygotic twin pairs: a large population-based co-twin-control study.

BACKGROUND: The widely reported inverse association between birth weight and risk of cardiovascular disease (CVD) has sparked theories about early life determinants of adult disease. Within-twin-pair analysis provides a unique opportunity to investigate whether factors shared within twin pairs influence the association. METHODS AND RESULTS: In a population-based cohort of like-sexed twins with known zygosity born in Sweden from 1926 to 1958, disease-discordant twin pairs were identified through linkage to the National Inpatient and Cause of Death registers between 1973 and 2006. Co-twin-control analyses were performed on twins discordant for cardiovascular disease (n=3884), coronary heart disease (n=2668), and stroke (n=1372). Overall, inverse associations between birth weight and risk of cardiovascular diseases were seen within dizygotic but not monozygotic twin pairs. In dizygotic twins, the odds ratios for a 1-kg within-pair increase in birth weight were 0.74 (95% confidence interval, 0.56 to 0.98) for coronary heart disease and 0.57 (95% confidence interval, 0.37 to 0.88) for stroke. Conversely, no statistically significant associations were found within monozygotic twins (for coronary heart disease: odds ratio, 1.10; 95% confidence interval, 0.73 to 1.68; for stroke: odds ratio, 0.92; 95% confidence interval, 0.48 to 1.80). CONCLUSIONS: We found an association between birth weight and risk of cardiovascular disease within disease-discordant dizygotic but not monozygotic twin pairs. This indicates that the association between birth weight and cardiovascular disease could be a result of common causes, and that factors that vary within dizygotic but not monozygotic twin pairs may help identify them.

Mortality from infancy to adolescence in singleton children conceived from assisted reproductive techniques versus naturally conceived singletons in Sweden.

OBJECTIVE: To assess infant (<1 year) and childhood (1-18 years) mortality in singletons conceived through assisted reproductive techniques (ART) versus naturally conceived singletons. DESIGN: Nationwide prospective study. SETTING: Sweden. PATIENT(S): All singleton liveborn infants born from 1983 to 2012 in Sweden identified using the Medical Birth Register (N = 2,847,108), of whom 43,506 were conceived through ART treatments including in vitro fertilization with and without intracytoplasmic sperm injection. INTERVENTION(S): None. MAIN OUTCOME MEASURES(S): Infant (<1 year) and childhood (1-18 years) mortality. RESULT(S): Data on ART treatment and covariates were retrieved from population-based registers using the unique personal identity number assigned to all permanent residents in Sweden. Cox proportional hazards models estimated the hazard ratios (HRs) with 95% confidence intervals (CIs) as measures of association between ART treatments and death. The analyses were adjusted for maternal characteristics, infertility, child sex, and birth cohort and were restricted to individuals with complete information on covariates for fully adjusted analysis. Compared with naturally conceived singletons, higher infant mortality risks were seen in infants conceived through ART (adjusted HR 1.45; 95% CI, 1.19-1.77), especially after transfer of cryopreserved embryos (adjusted HR 2.30; 95% CI, 1.46-3.64). Early neonatal mortality risk (deaths during the first week) was increased in children born after transfer of blastocysts (HR 2.40; 95% CI, 1.05-5.48). No increased mortality risk was observed between the ages of 1 and 18 years. CONCLUSION(S): Singletons conceived through ART had an increased risk of infant mortality from birth up to 1 year of life, predominantly in the early neonatal period and in pregnancies after transfer of frozen and thawed embryos.

The Uppsala-Stockholm Assisted Reproductive Techniques (UppStART) study.

PURPOSE: The Uppsala-Stockholm Assisted Reproductive Techniques (UppStART) study is a prospectively recruited sample of couples undergoing assisted reproduction in Stockholm and Uppsala county in Sweden. The study was initiated to (1) investigate possible changes in the epigenetic profile of infants inferred through the ART procedures and their consequence and (2) to assess the impact of lifestyle and health exposures on treatment outcome. PARTICIPANTS: Recruitment took place between September 2011 and December 2013, and in vitro fertilisation (IVF) cycles initiated and pregnancies conceived during this time were followed until December 2014. The cohort includes 971 participants (n= 514 women; n= 457 men), and 129 pregnancies were achieved from the first IVF cycle included in the study. FINDINGS TO DATE: Self-reported demographic, health and lifestyle data were collected from a baseline questionnaire, and to assess changes to lifestyle, a follow-up questionnaire was issued at the time of oocyte retrieval, and at subsequent IVF cycles. Questionnaire data were linked to data extracted from medical records. Biological samples were collected at baseline: blood for extraction of serum, plasma and DNA, morning and evening saliva samples for cortisol measurement and at delivery including samples of maternal blood, placenta and amniotic fluid, and cord blood for epigenetic analysis. FUTURE PLANS: Through the unique identification number assigned to each Swedish citizen at birth or immigration, UppStART study participants will be linked to the Swedish population-based national and quality registers to provide data from prenatal, obstetrical, neonatal and infant care, and subsequent updates will provide data on childhood health and educational outcomes. Collaboration and use of UppStART data is encouraged, and more information about access can be found at www.ki.se/meb/uppstart.

Investigating the effect of lifestyle risk factors upon number of aspirated and mature oocytes in in vitro fertilization cycles: Interaction with antral follicle count.

INTRODUCTION: There is evidence demonstrating that certain lifestyle factors have a detrimental effect on fertility. Since such factors often coexist, possible synergistic effects merit further investigation. Thus we aimed to examine the cumulative impact of lifestyle factors on in vitro fertilization (IVF) early reproductive treatment outcomes and their interaction with measures of ovarian reserve. MATERIALS AND METHODS: By following women who were starting their first fresh IVF cycle in 2 cohorts, the "Lifestyle study cohort" (hypothesis generating cohort, n = 242) and the "UppSTART study" (validation cohort, n = 432) in Sweden, we identified two significant risk factors acting independently, smoking and BMI, and then further assessed their cumulative effects. RESULTS: Women with both these risk factors had an Incidence Rate Ratio (IRR) of 0.75 [(95% CI 0.61-0.94)] regarding the number of aspirated oocytes compared to women without these risk factors. Concerning the proportion of mature oocytes in relation to the total number of aspirated oocytes, the interaction between BMI and Antral Follicle Count (AFC) was significant (p-value 0.045): the lower the value of AFC, the more harmful the effect of BMI with the outcome. CONCLUSIONS: Data shows that there is an individual as well as a cumulative effect of smoking and BMI on the number of aspirated and mature oocytes in fresh IVF treatment cycles. AFC might modify associations between BMI and the proportion of mature oocytes in relation to the total number of aspirated oocytes. These results highlight the importance of lifestyle factors on IVF early reproductive outcomes and provide additional evidence for the importance of preconception guidance for the optimization of IVF cycle outcome.

Polycystic ovary syndrome, personality, and depression: A twin study.

BACKGROUND: Women with polycystic ovary syndrome (PCOS) are at elevated risk for suffering from depression. Neuroticism is a personality trait that has been associated with an increased risk for developing major depressive disorder (MDD). The aim of the present study was to quantify and decompose the correlation between neuroticism, PCOS, and MDD into shared and unique genetic and environmental etiologies, by using quantitative genetic methods. METHODS: In a cohort of 12,628 Swedish female twins born from 1959 to 1985, neuroticism, PCOS identified by symptoms of hyperandrogenemia (i.e., hirsutism) and oligo- and/or anovulation, and lifetime MDD status were determined through questionnaire responses. Structural equation modeling was used to study the genetic and environmental sources of the variation within, and covariation between neuroticism, PCOS, and MDD. RESULTS: Female twins with PCOS (n=752) had significantly higher levels of neuroticism than women without PCOS, and a 2-fold increase in odds for a lifetime prevalence of MDD. The phenotypic correlation between PCOS and MDD was 0.19, with 63% of the correlation attributable to common genetic factors between the two traits. When taking into account neuroticism, 41% was attributable to common genetic factors and 9% attributable to common environmental factors shared between all three traits, with the remainder attributable to components unique to PCOS and MDD. CONCLUSION: There are common genetic factors between neuroticism, PCOS, and MDD; however, neuroticism shares approximately half of the genetic and environmental components behind the phenotypic correlation between PCOS and MDD, providing some etiological evidence behind the comorbidity between PCOS and depression.

Ovarian stimulation and risk of breast cancer in Swedish women.

OBJECTIVE: To investigate whether ovarian stimulation for treating infertility is associated with the risk of breast cancer. DESIGN: Nationwide register-based cohort study. SETTING: Not applicable. PATIENT(S): In a cohort of 1,340,211 women who gave birth 1982-2012, we investigated the relationship between assisted reproductive technology (ART) and incidence of breast cancer. Associations between any ovarian stimulation since 2005 and breast cancer incidence were studied in a separate cohort of 1,877,140 women born 1960-92. Both cohorts were followed through 2012. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer. RESULT(S): There was no increased risk of breast cancer in women who gave birth after ART compared with women who gave birth after spontaneous conception (adjusted HR, 0.84; 95% CI, 0.74-0.95). The incidence of breast cancer was not increased among women who received controlled ovarian stimulation or among women who received other hormonal fertility treatments since 2005, regardless of live birth (adjusted HR, 0.86; 95% CI, 0.69-1.07; and adjusted HR, 0.79; 95% CI, 0.60-1.05, respectively). CONCLUSION(S): No increased incidence of breast cancer was found among women who had gone through ovarian stimulations, including ART. These results are consistent with other studies and reassuring given the widespread and increasing use of ART.

Association Between Maternal Smoking During Pregnancy and Severe Mental Illness in Offspring.

Importance: Several recent population-based studies have linked exposure to maternal smoking during pregnancy to increased risk of severe mental illness in offspring (eg, bipolar disorder, schizophrenia). It is not yet clear, however, whether this association results from causal teratogenic effects or from confounding influences shared by smoking and severe mental illness. Objective: To examine the association between smoking during pregnancy and severe mental illness in offspring, adjusting for measured covariates and unmeasured confounding using family-based designs. Design, Setting, and Participants: This study analyzed population register data through December 31, 2013, for a cohort of 1 680 219 individuals born in Sweden from January 1, 1983, to December 31, 2001. Associations between smoking during pregnancy and severe mental illness in offspring were estimated with adjustment for measured covariates. Cousins and siblings who were discordant on smoking during pregnancy and severe mental illness were then compared, which helped to account for unmeasured genetic and environmental confounding by design. Exposures: Maternal self-reported smoking during pregnancy, obtained from antenatal visits. Main Outcomes and Measures: Severe mental illness, with clinical diagnosis obtained from inpatient and outpatient visits and defined using International Classification of Diseases codes for bipolar disorder and schizophrenia spectrum disorders. Results: Of the 1 680 219 offspring included in the analysis, 816 775 (48.61%) were female. At the population level, offspring exposed to moderate and high levels of smoking during pregnancy had greater severe mental illness rates than did unexposed offspring (moderate smoking during pregnancy: hazard ratio [HR], 1.25; 95% CI, 1.19-1.30; high smoking during pregnancy: HR, 1.51; 95% CI, 1.44-1.59). These associations decreased in strength with increasing statistical and methodologic controls for familial confounding. In sibling comparisons with within-family covariates, associations were substantially weaker and nonsignificant (moderate smoking during pregnancy: HR, 1.09; 95% CI, 0.94-1.26; high smoking during pregnancy: HR, 1.14; 95% CI, 0.96-1.35). The pattern of associations was consistent across subsets of severe mental illness disorders and was supported by further sensitivity analyses. Conclusions and Relevance: This population- and family-based study failed to find support for a causal effect of smoking during pregnancy on risk of severe mental illness in offspring. Rather, these results suggest that much of the observed population-level association can be explained by measured and unmeasured factors shared by siblings.

Hidden heritability due to heterogeneity across seven populations.

Meta-analyses of genome-wide association studies (GWAS), which dominate genetic discovery are based on data from diverse historical time periods and populations. Genetic scores derived from GWAS explain only a fraction of the heritability estimates obtained from whole-genome studies on single populations, known as the 'hidden heritability' puzzle. Using seven sampling populations (N=35,062), we test whether hidden heritability is attributed to heterogeneity across sampling populations and time, showing that estimates are substantially smaller from across compared to within populations. We show that the hidden heritability varies substantially: from zero (height), to 20% for BMI, 37% for education, 40% for age at first birth and up to 75% for number of children. Simulations demonstrate that our results more likely reflect heterogeneity in phenotypic measurement or gene-environment interaction than genetic heterogeneity. These findings have substantial implications for genetic discovery, suggesting that large homogenous datasets are required for behavioural phenotypes and that gene-environment interaction may be a central challenge for genetic discovery.

Polycystic ovary syndrome and psychiatric disorders: Co-morbidity and heritability in a nationwide Swedish cohort.

Polycystic ovary syndrome (PCOS) is an endocrine disorder affecting 5-15% of reproductive-aged women and characterized by high levels of circulating androgens. Given that androgens have been implicated in the aetiology of several psychiatric disorders, it was hypothesized that women with PCOS have high risk for psychiatric comorbidity. We aimed to investigate this risk amongst women with PCOS, as well as in their siblings, to elucidate if familial factors underlie any potential associations. Using the Swedish national registers, we identified all women diagnosed with PCOS between 1990 and 2013 (n=24,385), their full-siblings (n=25,921), plus matched individuals (1:10/100) from the general population and their full-siblings. Psychiatric disorder diagnoses were identified including schizophrenia, bipolar disorder, depressive and anxiety disorders, eating disorders, personality and gender identity disorder, autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), tics, attempted and completed suicide. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression and adjusted ORs (AOR) were determined by adjustment for comorbid psychiatric disorders. Overall, women with PCOS had an increased odds of having at least one psychiatric disorder (OR=1.56 [95CI%, 1.51-1.61]). Crude ORs showed associations with nearly all psychiatric disorders included in this study. Following adjustment for comorbid psychiatric disorders, women with PCOS were still at a significantly increased risk for bulimia, schizophrenia, bipolar disorder, depressive and anxiety disorders, personality disorders, with the highest AORs for ASD (AOR=1.55 [95%CI, 1.32-1.81]) and tics (AOR=1.65 [95%CI, 1.10-2.47]). Significantly higher AORs were found for ASD in both brothers and sisters of women with PCOS, and for depressive, anxiety, and schizophrenia spectrum disorders in the sisters only. Notably, the crude ORs for attempted suicide were 40% higher in women with PCOS and 16% higher in their unaffected sisters. However, the AORs were greatly attenuated indicating that underlying psychiatric comorbidity is important for this association. Women with PCOS had higher risks for a range of psychiatric disorders not shown before. Elevated risk in their siblings suggests shared familial factors between PCOS and psychiatric disorders. This study is an important first step towards identifying the underlying mechanisms for risk of psychiatric disorders in women with PCOS. Health professionals treating women with PCOS should be aware that these patients - as well as their family members - are important targets for mental health care.