Congenital Tooth Agenesis and Risk of Early-Onset Cancer

Importance

There is some evidence that tooth agenesis (congenital absence of 1 or more teeth) is associated with cancer risk, especially carcinomas of the colon and ovaries, but results of previous studies are conflicting, and associations have not yet been evaluated in a population-based setting.

Objective

To examine the association between tooth agenesis and specific cancer types before 40 years of age.

Design, Setting, and Participants

This population-based cohort study used linking data from nationwide registries in Denmark to assess all Danish live-born singletons born from January 1, 1977, to December 31, 2018, and followed up for up to 40 years. Data were analyzed from January through June 2023.

Exposure

Tooth agenesis as documented by the Danish Central Registry of Odontology (Danish municipal pediatric dental care) from January 1, 1988, to December 31, 2018, and from hospital encounters in the Danish National Patient Registry within the entire study period.

Main Outcome and Measures

The primary outcome was first cancer diagnosis before 40 years of age obtained from the Danish Cancer Registry. Associations between tooth agenesis and specific cancers were estimated by Cox proportional hazards regression as hazard ratios (HRs) with 95% CIs. Analyses were split into age groups: younger than 1 year, 1 to younger than 3 years, 3 to younger than 10 years, 10 to younger than 20 years, 20 to younger than 30 years, and 30 to younger than 40 years. Associations with nonsyndromic tooth agenesis were evaluated after exclusion of individuals with known syndromes.

Results

Among 2 501 715 included individuals (1 284 292 [51.3%] male), 70 288 (2.8%) had a diagnosis of tooth agenesis (mean [SD] age at diagnosis, 13.2 [4.1] years) and 26 308 (1.1%) had a diagnosis of early-onset cancer within the study period; 778 individuals had co-occurrence of tooth agenesis and cancer. Overall, tooth agenesis was positively associated with several cancer types, including neuroblastoma (age 1 to <3 years; HR, 4.20; 95% CI, 2.24-7.88), nephroblastoma (age 1 to <3 years; HR, 4.59; 95% CI, 2.37-8.91), hepatoblastoma (age 1 to <3 years; HR, 7.10; 95% CI, 2.70-18.68), osteosarcoma (age 10 to <20 years; HR, 2.19; 95% CI, 1.11-4.32), colorectal carcinomas (age 30 to <40 years; HR, 2.81; 95% CI, 1.38-5.71), and carcinomas of bladder (age 20 to <30 years; HR, 3.35; 95% CI, 1.35-8.30).

Conclusions and Relevance

This cohort study found associations between congenital tooth agenesis and several cancer types, from childhood to early adulthood. Further evaluation of these associations is needed to assess possible clinical implications.

Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude

BACKGROUND

Seasonal variations in environmental exposures at birth or during gestation are associated with numerous adult traits and health outcomes later in life. Whether DNA methylation (DNAm) plays a role in the molecular mechanisms underlying the associations between birth season and lifelong phenotypes remains unclear.

METHODS

We carried out epigenome-wide meta-analyses within the Pregnancy And Childhood Epigenetic Consortium to identify associations of DNAm with birth season, both at differentially methylated probes (DMPs) and regions (DMRs). Associations were examined at two time points: at birth (21 cohorts, N = 9358) and in children aged 1-11 years (12 cohorts, N = 3610). We conducted meta-analyses to assess the impact of latitude on birth season-specific associations at both time points.

RESULTS

We identified associations between birth season and DNAm (False Discovery Rate-adjusted p values < 0.05) at two CpGs at birth (winter-born) and four in the childhood (summer-born) analyses when compared to children born in autumn. Furthermore, we identified twenty-six differentially methylated regions (DMR) at birth (winter-born: 8, spring-born: 15, summer-born: 3) and thirty-two in childhood (winter-born: 12, spring and summer: 10 each) meta-analyses with few overlapping DMRs between the birth seasons or the two time points. The DMRs were associated with genes of known functions in tumorigenesis, psychiatric/neurological disorders, inflammation, or immunity, amongst others. Latitude-stratified meta-analyses [higher (≥ 50°N), lower (< 50°N, northern hemisphere only)] revealed differences in associations between birth season and DNAm by birth latitude. DMR analysis implicated genes with previously reported links to schizophrenia (LAX1), skin disorders (PSORS1C, LTB4R), and airway inflammation including asthma (LTB4R), present only at birth in the higher latitudes (≥ 50°N).

CONCLUSIONS

In this large epigenome-wide meta-analysis study, we provide evidence for (i) associations between DNAm and season of birth that are unique for the seasons of the year (temporal effect) and (ii) latitude-dependent variations in the seasonal associations (spatial effect). DNAm could play a role in the molecular mechanisms underlying the effect of birth season on adult health outcomes.

Congenital heart disease and the risk of impaired fertility: A Danish nationwide cohort study using time to pregnancy

BACKGROUND

The number of women with congenital heart disease (CHD) becoming pregnant are increasing. Although menstrual irregularities appear to occur more often in these patients, knowledge on their fertility is limited. In this nationwide cohort study, we evaluated the risk of impaired fertility in women with CHD compared with unaffected women using time to pregnancy (TTP).

METHODS

The Danish National Birth Cohort (DNBC) of pregnant women constituted the study population. Information on TTP and use of medically assisted reproduction (MAR) treatment was reported at a first trimester interview. Women with CHD were identified by linkage to the Danish National Patient Registry. TTP was divided into three categories; 0-5 months, 6-12 months (i.e. subfertile), and > 12 months or use of MAR treatment (i.e. infertile). Relative risk ratios (RRR) for subfertility and infertility with 95% confidence intervals were estimated using multinomial logistic regression.

RESULTS

Among 93,832 pregnancies in 84,922 women, CHD was diagnosed in 333 women (0.4%), contributing with 360 pregnancies. The CHD was of simple complexity in 291 women (87.4%). No association was found between CHD and longer TTP (RRR of 1.02 (95% CI: 0.75-1.40) for subfertility, and RRR of 0.86 (95% CI: 0.61-1.20) for infertility). Similar was observed when comparing women with simple CHD and unaffected women. The number of women with complex CHD was too low for evaluation.

CONCLUSIONS

Women with CHD had no increased risk of impaired fertility, assessed by TTP, when compared with unaffected women. Separate analysis of women with complex CHD was hampered by low numbers.

Maternal age at menarche and reproductive health in young adult men: a cohort study

STUDY QUESTION

Is maternal age at menarche associated with reproductive health in sons measured by semen quality, testes volume and reproductive hormone levels?

SUMMARY ANSWER

Later maternal age at menarche was associated with impaired semen characteristics, lower testes volume and altered levels of reproductive hormones, while earlier maternal age at menarche was not strongly associated with reproductive outcomes in sons.

WHAT IS KNOWN ALREADY

Both earlier and later maternal age at menarche may be associated with altered male reproductive health outcomes. This is the first study to investigate the potential association between maternal age at menarche and semen quality, testes volume and reproductive hormone levels in sons.

STUDY DESIGN, SIZE, DURATION

In this population-based cohort study, we used data from the Fetal Programming of Semen Quality Cohort nested within the Danish National Birth Cohort. In total, 5697 sons born in 1998-2000 were invited to participate in the cohort in 2017-2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 1043 (18% of the invited) young men with information on maternal age at menarche provided a semen and blood sample, measured their testes volume, and filled in a questionnaire on health behavior and pubertal development. Maternal age at menarche was reported by the mothers during pregnancy and examined categorically (as earlier, at the same time or later than their peers), continuously and modeled as splines. We estimated relative percentage differences in the reproductive outcomes using negative binomial regression models. Further, we did a mediation analysis to investigate the potential mediating role of timing of the sons' pubertal development.

MAIN RESULTS AND THE ROLE OF CHANCE

Sons whose mothers had age at menarche later than peers had 15% lower (95% CI: -27%; 0%) sperm concentration, 14% lower (95% CI: -28%; 1%) total sperm count, 7% higher (95% CI: 0%; 14%) proportion of nonprogressive or immotile spermatozoa, 6% lower (95% CI: -11%; 0%) testes volume, 6% lower (95% CI: -12%; 1%) luteinizing hormone, 6% lower (95% CI: -12%; 1%) sex hormone-binding globulin and 5% lower (95% CI: -9%; 0%) testosterone levels compared with sons whose mothers had age at menarche at the same time as peers. Our study did not suggest that earlier maternal age at menarche was strongly associated with semen quality, testes volume or reproductive hormones in sons. However, the spline analyses indicated a potential inverted U-shaped association for sperm concentration and testes volume, and levels of sex hormone-binding globulin and testosterone. We found no strong evidence of mediation by timing of the sons' own pubertal development.

LIMITATIONS, REASONS FOR CAUTION

There was a rather low participation rate in the Fetal Programming of Semen Quality Cohort and we tried to counter it by applying selection weights. Maternal age at menarche was recalled during pregnancy, which may introduce misclassification, most likely nondifferential. Inaccuracy of the sons' recalled pubertal development years after the event may result in underestimation of the possible mediating role of pubertal timing.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings may represent a degree of shared heritability of reproductive health or be a result of an underlying epigenetic profile or unknown shared environmental, cultural or dietary exposure, causing both altered age at menarche and impaired reproductive health outcomes in sons. However, the exact mechanism for the investigated association remains unknown.

STUDY FUNDING/COMPETING INTEREST(S)

This article is part of the ReproUnion collaborative study, cofinanced by the European Union, Intereg V ÖKS (20200407). The FEPOS project was further funded by the Lundbeck Foundation (R170-2014-855), the Capital Region of Denmark, Medical doctor Sofus Carl Emil Friis and spouse Olga Doris Friis's Grant, Axel Muusfeldt's Foundation (2016-491), A.P. Møller Foundation (16-37), the Health Foundation and Dagmar Marshall's Fond. Additionally, this study received funding from Aarhus University. There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Gender incongruence and timing of puberty: a population-based cohort study

OBJECTIVE

To study whether the timing of puberty in adolescents who reported gender incongruence (incongruence between birth-assigned sex and self-identified gender) was different from those adolescents who reported gender congruence.

DESIGN

Population-based cohort study using data from the Danish National Birth Cohort.

SETTING

Not applicable.

PATIENT(S)

Birth-assigned boys and girls born between 2000 and 2003, who self-reported gender incongruence at 11 years (N = 10,046) and their pubertal developmental stages from age 11 years to every 6 months throughout puberty were included.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE

Mean age differences in months at reaching Tanner stages 2-5 for breast or genital development and pubic hair, voice break, first ejaculation, menarche, axillary hair, acne, and the average difference at attaining all pubertal milestones (primary outcome).

RESULT(S)

In total, 549 (5.5% ) adolescents reported part or full gender incongruence at 11 years. Tendencies toward earlier timing of puberty were observed in adolescents who reported part gender incongruence (average difference, birth-assigned boys: -3.2 months [95% confidence interval {CI}: -6.7; 0.3]; birth-assigned girls: -2.0 months [95% CI: -3.9; -0.1]). Tendencies toward earlier timing of puberty were observed in adolescents who reported full gender incongruence (average difference, birth-assigned boys: -2.4 months [95% CI: -5.0; 0.4]; birth-assigned girls: -1.9 months [95% CI: -5.1; 1.2]).

CONCLUSIONS

The results from this study indicated that birth-assigned boys and girls who reported either part or full gender incongruence tended to reach puberty slightly earlier than those adolescents who reported gender congruence at 11 years of age. Knowledge on the timing of puberty among adolescents who experience gender incongruence is essential to inform mutual decision-making in clinical settings.

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.

Maternal thyroid disease in pregnancy and timing of pubertal development in sons and daughters

OBJECTIVE

To study whether maternal thyroid disease in pregnancy is associated with pubertal timing in sons and daughters.

DESIGN

Cohort study.

SETTING

National birth cohort and health registers.

PATIENT(S)

A total of 15,763 mothers and children from the Danish National Birth Cohort and its Puberty Cohort.

INTERVENTION(S)

Register-based and self-reported information on maternal thyroid diseases during pregnancy (hyperthyroidism, hypothyroidism, benign goiter, or no thyroid disease [reference group]).

MAIN OUTCOME MEASURE(S)

The adjusted mean age difference (months) at attaining several self-reported pubertal milestones collected every 6 months using an interval-censored regression and the average difference in age at attaining all pubertal milestones using the Huber-White robust variance estimation (primary outcome).

RESULT(S)

Sons of mothers with hyperthyroidism had earlier pubertal development (average difference, -2.9 [95% confidence interval (CI), -5.0 to -0.7] months) than unexposed sons. Maternal hypothyroidism was not associated with pubertal development in sons (average difference, -1.2 [95% CI, -5.1 to 2.7] months). We observed nonstatistically significant indications of earlier pubertal development in sons of mothers with benign goiter (average difference, -1.9 [95% CI, -4.6 to 0.9] months). Maternal thyroid disease was not associated with pubertal development in daughters (average difference (months), hyperthyroidism, -0.8 [95% CI, -2.8 to 1.2]; hypothyroidism, 0.3 [95% CI, -3.1 to 3.8]; and benign goiter, 0.7 [95% CI, -2.0 to 3.4]).

CONCLUSION(S)

We found indications of earlier pubertal development in sons of mothers with hyperthyroidism. More research is needed to further investigate the observed sex-specific association.

Working life, health and well-being of parents: a joint effort to uncover hidden treasures in European birth cohorts

Objective

Birth cohorts collect valuable and under-utilized information on employment and health of parents before and during pregnancy, at birth, and sometimes after birth. In this discussion paper, we examine how these data could be exploited to study the complex relationships and interactions between parenthood, work, and health among parents themselves.

Methods

Using a web-based database of birth cohorts, we summarize information on maternal employment and health conditions and other potentially related variables in cohorts spread throughout Europe. This provided information on what data are available and could be used in future studies, and what was missing if specific questions are to be addressed, exploiting the opportunity to explore work–health associations across heterogenous geographical and social contexts.

Results

We highlight the many potentialities provided by birth cohorts and identify gaps that need to be addressed to adopt a life-course approach and investigate topics specific to the peri-pregnancy period, such as psychosocial aspects. We address the technical difficulties implied by data harmonization and the ethical challenges related to the repurposing of data, and provide scientific, ecological and economic arguments in favor of improving the value of data already available as a result of a serious investment in human and material resources.

Conclusions

There is a hidden treasure in birth cohorts that deserves to be brought out to study the relationships between employment and health among working parents in a time when the boundaries between work and life are being stretched more than ever before.

Breast feeding and timing of puberty in boys and girls: A nationwide cohort study

BACKGROUND

Breast feeding has been associated with improved infant health, but its impact on pubertal timing remains uncertain, particularly in boys.

OBJECTIVE

The objective of this study was to investigate the association between duration of breast feeding and pubertal timing in boys and girls.

METHODS

This population-based cohort study included 13 511 boys and girls from the Puberty Cohort nested within the Danish National Birth Cohort. The children gave half-yearly, self-reported information on pubertal development through questionnaires (Tanner stages, age at menarche, first ejaculation, voice break, axillary hair growth, and acne). Information on breast feeding was provided by the mothers when the children were 6 months of age. We estimated mean differences (in months) in age at attaining each pubertal marker and for overall timing of puberty (combined estimate) for every additional month of exclusive breast feeding. Furthermore, we estimated differences in pubertal age when comparing children never exclusively breastfed and exclusively breastfed <4 months using children exclusively breastfed ≥4 months as reference. In sub-analyses, we further adjusted for infant weight gain and childhood BMI at 7 years to investigate whether these variables mediated the association.

RESULTS

Boys tended to reach pubertal markers later for every additional month of exclusive breast feeding (combined estimate: 0.2 (95% confidence interval [CI] 0.0, 0.4 months). Never exclusively breastfed boys reached pubertal markers earlier than the boys exclusively breastfed ≥4 months (combined estimate: -4.1 (95% CI -6.7, -1.6) months). Boys exclusively breastfed <4 months also reached pubertal markers earlier than those never exclusively breastfed but with smaller differences. In girls, duration of breast feeding was not associated with pubertal development. When including infant weight gain or childhood BMI, the results remained essentially unchanged.

CONCLUSIONS

Shorter duration of exclusive breast feeding was associated with earlier pubertal development in boys but not in girls.

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.

Hypertensive disorders in pregnancy and timing of pubertal development in daughters and sons

STUDY QUESTION

Do maternal hypertensive disorders affect pubertal development in daughters and sons?

SUMMARY ANSWER

Pubertal development tended to occur earlier in daughters of mothers with 'preeclampsia, eclampsia or HELLP syndrome' (hemolysis, elevated liver enzymes and low blood platelets) or hypertension in pregnancy compared to daughters born of normotensive mothers.

WHAT IS KNOWN ALREADY

The existing literature suggests some or no association between preeclampsia and pubertal development in daughters, but not in sons. None of the previous studies has investigated the possible association between other types of hypertensive disorders (hypertension, eclampsia or HELLP syndrome) and pubertal timing in children.

STUDY DESIGN, SIZE, DURATION

Longitudinal cohort study consisting of 15 819 mother-child pairs with information on maternal hypertensive disorders collected during pregnancy and information on pubertal development collected half-yearly from the age of 11 years and until fully developed or 18 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants are children from the Puberty Cohort nested within the Danish National Birth Cohort. The exposure was register-based and self-reported information on maternal hypertensive disorders during pregnancy. The outcomes were children's self-reported information on pubertal development, including Tanner stage 1-5 (pubic hair (both daughters and sons) and breast development (daughters) or genital development (sons)), first menstrual bleeding (daughters) or first ejaculation (sons), voice break episode (sons), axillary hair development and acne occurrence (both daughters and sons). The main outcome was mean difference in age at attaining each pubertal milestone and a combined pubertal marker in children of mothers with hypertensive disorders in pregnancy (either hypertension (n = 490), 'preeclampsia, eclampsia or HELLP syndrome' (n = 419) or 'unspecific hypertensive disorders' (n = 334) with unexposed children as reference (n = 14 576)).

MAIN RESULTS AND THE ROLE OF CHANCE

In daughters of mothers with 'preeclampsia, eclampsia or HELLP syndrome', we observed tendencies of earlier pubertal timing (combined marker: -2.0 (95% CI: -3.9; 0.0) months). In daughters of mothers with hypertension, several pubertal milestones tended to occur earlier than in daughters of normotensive mothers; however, all 95% CIs overlapped the null resulting in a combined pubertal marker of -1.0 (95% CI: -3.2; 1.1) months. In sons of mothers with any of the hypertensive disorders, we observed no difference in pubertal timing (combined markers: 'preeclampsia, eclampsia or HELLP syndrome': 0.1 (95% CI: -2.0; 2.1) months; hypertension: -0.6 (95% CI: -2.3; 1.1) months; 'unspecific hypertensive disorders': 0.2 (95% CI: -1.9; 2.2) months).

LIMITATIONS, REASONS FOR CAUTION

The study is subject to non-differential misclassification of self-reported information on maternal hypertensive disorders in pregnancy and current pubertal status; possibly causing bias toward the null.

WIDER IMPLICATIONS OF THE FINDINGS

Hypertensive disorders in pregnancy might accelerate pubertal timing in daughters; however, more studies are needed for causal conclusions.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Faculty of Health at Aarhus University. The authors have no financial relationships or competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Maternal pre-pregnancy overweight and infertility in sons and daughters: A cohort study

INTRODUCTION

Overweight and obesity in pregnancy is increasing worldwide and may harm the developing fetus, including its future reproductive health. We therefore studied the association between in utero exposure to maternal overweight and obesity and infertility in adulthood. No studies have previously assessed this association.

MATERIAL AND METHODS

We performed a cohort study with 9232 adult sons and daughters whose mothers were enrolled in the Danish Healthy Habits for Two cohort during pregnancy in 1984-87. Participants were sons and daughters followed in the Danish In-Vitro-Fertilization-Register and Danish National Patient Register until February 2018 for diagnoses of infertility.

RESULTS

In total, 1203 (13%) sons and daughters were born to mothers with a body mass index (BMI) >25 kg/m² ; 871 (9.4%) of the participants were identified as being infertile during follow-up. Sons of overweight mothers had slightly increased odds of infertility compared with sons of mothers with normal body weight (BMI 18.5-24.9 kg/m² , adjusted odds ratio 1.4, 95% confidence interval [CI] 1.0-1.9). Cubic spline analyses with continuous BMI levels showed increasing odds with higher levels of BMI; however, for BMI >29 kg/m² the confidence intervals were too wide to draw conclusions. No association between maternal overweight and infertility was found among daughters (adjusted odds ratio 0.9, 95% CI 0.7-1.2)).

CONCLUSIONS

Sons born to overweight mothers had higher odds of infertility compared with sons of normal weight mothers. No association between maternal overweight and infertility was observed in daughters. Prevention of overweight during pregnancy may be an important tool to preserve fecundity in future generations.

Female cigarette smoking and successful fertility treatment: A Danish cohort study

INTRODUCTION

Despite smoking being a well-established risk factor for adverse pregnancy and neonatal outcomes, a substantial proportion of women of reproductive age smoke. Previously, meta-analyses have indicated a significantly negative impact of female smoking on outcomes of assisted reproduction, yet most of the included studies have several, essential methodological limitations. We aimed to investigate whether female cigarette smoking may affect the chance of achieving a clinical pregnancy and live birth among women and couples receiving medically assisted reproduction treatment.

MATERIAL AND METHODS

A cohort study with longitudinally and repeatedly collected exposure information from 1 January 2010 to 31 August 2015, including data on 1708 women and potential partners initiating either intrauterine insemination, in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) or frozen embryo transfer treatment cycles at the public Fertility Clinic, Aarhus University Hospital, Denmark. Smoking was assessed from self-reported questionnaires completed before treatment. Outcomes were a clinical pregnancy and a live birth. Information on these was obtained from the Danish national health registries, allowing complete follow-up. To evaluate associations between female occasional/daily cigarette smoking and successful medically assisted reproduction treatments, a modified Poisson regression with robust standard errors was used.

RESULTS

Female occasional/daily cigarette smoking was not associated with the chance of achieving a clinical pregnancy or a live birth in all intrauterine insemination or IVF/ICSI treatment cycles. When compared with nonsmokers, the adjusted relative risk for obtaining a live birth for those reporting smoking was 1.22 (0.70-2.12) among women initiating 1456 intrauterine insemination treatment cycles. Among women initiating 2788 IVF/ICSI treatment cycles, those reporting occasional/daily smoking had a relative risk for obtaining a live birth of 1.15 (0.82-1.60) when compared with nonsmokers.

CONCLUSIONS

Occasionally/daily cigarette smoking women had similar chance of achieving a clinical pregnancy or a live birth as the nonsmokers when receiving medically assisted reproduction treatments. However, tobacco use before and during pregnancy remains a major cause of reduced fertility as well as maternal, fetal, and infant morbidity and mortality, and should strongly be discouraged.

Prenatal exposure to antibiotics and timing of puberty in sons and daughters: A population-based cohort study

OBJECTIVE

To investigate if prenatal exposure to antibiotics is associated with earlier timing of pubertal development in sons and daughters.

STUDY DESIGN

This population-based cohort study is based upon the Puberty Cohort and includes a sample of 15,638 children born 2000-2003 in Denmark. Information on maternal use of antibiotics was collected around gestational week 30 and 6 months postpartum. The children were followed-up half-yearly from 11 years of age and throughout sexual maturation providing information on Tanner stages, acne and axillary hair, in addition to voice break and first ejaculation in sons and menarche in daughters. Due to the half-yearly collection of data on pubertal timing, the data was censored and therefore analysed using a multivariable censored time-to-event regression model. We examined both prenatal exposure to antibiotics at any time in pregnancy and trimester-specific prenatal exposure to antibiotics and pubertal timing, adjusting for maternal baseline socioeconomic and lifestyle characteristics. Mean age differences for the pubertal milestones between exposure groups were estimated. A combined estimate for overall pubertal timing was calculated based on combining all pubertal milestones into one model for sons and daughters, using Huber-White robust variance estimation which handles the risk of type 1 errors due to multiple testing of correlated outcomes. An active comparator approach with restriction to women reporting to have a urinary tract infection (cystitis) treated with either penicillin or sulfonamides was employed in a sub-analysis.

RESULTS

The prevalence of any maternal use of antibiotics in pregnancy was 21.1 %. There was no association between prenatal exposure to antibiotics and timing of pubertal development for the individual milestones. The adjusted combined estimate for pubertal timing in sons prenatally exposed to antibiotics at any point in pregnancy was -0.4 (95 % confidence interval (CI): -1.2; 0.4) months compared to unexposed sons. The adjusted combined estimate for pubertal timing in daughters prenatally exposed to antibiotics at any point in pregnancy was -0.1 (95 % CI: -0.9; 0.7) months compared to unexposed daughters. Both the trimester-specific analyses and the active comparator analysis revealed similar results.

CONCLUSION

Prenatal exposure to antibiotics was not associated with pubertal timing.

Reproductive life in women with celiac disease; a nationwide, population-based matched cohort study

STUDY QUESTION

How does celiac disease (CD) influence women's reproductive life, both prior to and after the diagnosis?

SUMMARY ANSWER

Prior to the diagnosis of CD, an increased risk of adverse pregnancy outcomes was seen, whereas after the diagnosis, no influence on reproductive outcomes was found.

WHAT IS KNOWN ALREADY

CD has been associated with several conditions influencing female reproduction and pregnancy outcomes including spontaneous abortion and stillbirth.

STUDY DESIGN, SIZE, DURATION

A nationwide matched cohort study following 6319 women diagnosed with CD and 63166 comparison women and identifying reproductive events between the ages of 15 and 50 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Through linkage of several Danish national health registers, we identified all women diagnosed with CD between 1977 and 2016. We identified an age- and sex-matched comparison cohort and obtained data on reproductive outcomes for both cohorts. Adjusted stratified Cox and logistic regression models were used to estimate differences in reproductive outcomes between women with and without CD.

MAIN RESULTS AND THE ROLE OF CHANCE

Comparing women with diagnosed CD with the non-CD women, the chance of pregnancy, live birth and risk of stillbirth, molar and ectopic pregnancy, spontaneous abortion and abortion due to foetal disease was the same. However, prior to being diagnosed, CD women had an excess risk of spontaneous abortion equal to 11 extra spontaneous abortions per 1000 pregnancies (adjusted odds ratio (OR) = 1.12, 95% CI: 1.03, 1.22) and 1.62 extra stillbirths per 1000 pregnancies (adjusted OR = 1.57, 95% CI: 1.05, 2.33) compared with the non-CD women. In the period 0-2 years prior to diagnosis fewer pregnancies occurred in the undiagnosed CD group, equal to 25 (95% CI: 20-31) fewer pregnancies per 1000 pregnancies compared to the non-CD group and in addition, fewer undiagnosed CD women initiated ART-treatment in this period, corresponding to 4.8 (95% CI: 0.9, 8.7) fewer per 1000 women compared to non-CD women.

LIMITATIONS, REASONS FOR CAUTION

Validity of the diagnoses in the registers was not confirmed, but reporting to the registers is mandatory for all hospitals in Denmark. Not all spontaneous abortions will come to attention and be registered, whereas live- and stillbirths, ectopic and molar pregnancies and abortion due to foetal disease are unlikely not to be registered. We adjusted for several confounding factors but residual confounding cannot be ruled out.

WIDER IMPLICATIONS OF THE FINDINGS

These findings suggest that undiagnosed CD can affect female reproduction and the focus should be on early detection of CD in risk groups.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Health Research Fund of Central Denmark Region and The Hede Nielsens Foundation, Denmark. The authors report no conflicts of interest in this work.

Alcohol intake during pregnancy and timing of puberty in sons and daughters: A nationwide cohort study

We explored whether maternal alcohol intake in early pregnancy is associated with pubertal timing in sons and daughters. In total, 15,819 children, born 2000-2003 within the Danish National Birth Cohort, gave half-yearly, self-reported information on pubertal development (Tanner stages, voice break, first ejaculation, menarche, acne, and axillary hair) from 11 years during 2012-2018. Information on maternal average alcohol intake in first trimester and binge drinking episodes (intake of ≥5 drinks on the same occasion) in first trimester was self-reported by mothers during pregnancy. Average alcohol intake of 5+ weekly drinks in first trimester was not associated with pubertal timing in sons (with no alcohol intake as the reference). A tendency towards earlier pubertal timing was observed in daughters (-2.0 (95 % confidence interval: -4.2, 0.3) months) when combining the estimates for all pubertal milestones. Binge drinking was not associated with pubertal timing in neither sons nor daughters.

Pubertal development after unintended intrauterine exposure to oral contraceptives: a nationwide cohort study

OBJECTIVE

To study the associations between exposure to oral contraceptives before conception and early in pregnancy and pubertal timing in boys and girls.

DESIGN

Population-based cohort study.

SETTING

Not applicable.

PATIENT(S)

Overall, 15,800 children (70%) born during 2000-2003 into the Danish National Birth Cohort were categorized according to maternal use of combined oral contraceptive pills or progestin-only pills reported around gestational week 17: no exposure (reference), exposure 4 months before conception, and exposure in early pregnancy. Children self-assessed pubertal status using Web-based questionnaires from 11 years and biannually throughout puberty.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Adjusted mean age differences (months) for attaining individual pubertal milestones and overall pubertal timing. Proportion mediated by prepubertal body mass index.

RESULT(S)

In boys, intrauterine exposure to oral contraceptives showed a tendency toward slightly earlier mean age for voice break (months, -3.8; 95% confidence interval [CI] -6.5, -1.0) and first ejaculation (months, -2.9; 95% CI -5.9, 0.1) and a mean difference of -1.4 months (95% CI -3.3, 0.4) for overall pubertal timing. Girls with intrauterine exposure tended to have slightly earlier age at menarche (months, -1.9; 95% CI -4.0, 0.3) and Tanner breast stages and had a mean difference of -0.9 months (95% CI -2.7, 1.0) for overall pubertal timing. Exposure before conception was not associated with pubertal timing. Prepubertal body mass index did not play a mediating role.

CONCLUSION(S)

This study shows some evidence that intrauterine exposure to oral contraceptives might slightly affect pubertal timing.

Oral contraceptive use and genital anomalies in sons. A Danish cohort study

Exposure to exogenous sex hormones with estrogenic or anti-androgen properties may influence intrauterine development of male genitals. This population-based cohort study based on data from 44,408 live-born singleton sons in the Danish National Birth Cohort (DNBC) aimed to investigate whether maternal use of oral contraceptives prior to or during early pregnancy increase the risk of cryptorchidism or hypospadias. We found no consistent association between use of oral contraceptives and cryptorchidism or hypospadias, neither in those exposed any time four months prior to conception [cryptorchidism: adjusted Odds Ratio (aOR): 1.06 (95% CI: 0.91; 1.23), hypospadias: 0.74 (95% CI: 0.53; 1.03)] nor in those exposed any time during the first trimester of pregnancy [cryptorchidism: aOR: 0.93 (95% CI: 0.53; 1.62), hypospadias: 1.02 (95% CI: 0.32; 3.23)]. Despite relatively strong exposure levels from oral contraceptive use in pregnancy, this study revealed no evidence of an increased risk of either two genital malformations.

Low-to-moderate alcohol consumption and success in fertility treatment: a Danish cohort study

STUDY QUESTION

Does female weekly alcohol intake and binge drinking impact the chance of a successful fertility treatment?

SUMMARY ANSWER

Low-to-moderate weekly alcohol drinking and binge drinking were not associated with the chance of achieving a clinical pregnancy or a live birth among women and couples undergoing medically assisted reproduction (MAR) treatments.

WHAT IS KNOWN ALREADY

Alcohol consumption is common among women of reproductive age, even though health authorities advise women trying to conceive to abstain from drinking. A growing number of couples struggle with infertility, but it is unknown whether low-to-moderate levels of alcohol consumption and alcohol binge drinking impair success in fertility treatment.

STUDY DESIGN, SIZE, DURATION

Cohort study with prospectively collected exposure information including 1708 women and potential partners undergoing fertility treatment at the public fertility clinic, Aarhus University Hospital, 1 January 2010 to 31 August 2015. In total, data on 1511 intrauterine insemination (IUI) cycles, 2870 in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles and 1355 frozen embryo transfer cycles.

PARTTICIPANTS/MATERIALS, SETTING, METHODS

Exposure to weekly average alcohol intake was assessed from questionnaires completed by participants before the start of treatment. Outcome measures are the achievement of a clinical pregnancy and live birth in consecutive treatment cycles in the Danish national health registries, enabling complete follow-up. A modified Poisson regression with robust standard errors was used to evaluate associations between a weekly average alcohol intake and MAR outcomes, adjusting for female age, body mass index, cigarette smoking, coffee consumption, chronic diseases, level of education, and cycle number. When evaluating the association between binge drinking in the month prior to baseline and MAR outcomes the analyses were further adjusted for average weekly alcohol consumption.

MAIN RESULTS AND THE ROLE OF CHANCE

Low-to-moderate average weekly alcohol intake was not statistically significantly associated with the chance of achieving a clinical pregnancy or a live birth following IUI or IVF/ICSI treatment cycles. Compared to women abstaining from alcohol, the adjusted relative risks for achieving a live birth among those reporting 1–2, 3–7, and &gt;7 drinks per week were 1.00 (95% CI 0.66; 1.53), 1.20 (0.76; 1.91), and 1.48 (0.56; 3.93), respectively, among women initiating IUI treatments. Among those initiating IVF/ICSI treatments, the chance for achieving a live birth among those reporting 1–2, 3–7, and &gt;7 drinks per week were 1.00 (0.83; 1.21), 0.95 (0.75; 1.20), and 0.89 (0.53; 1.51), respectively. The chance of achieving a live birth in the first IUI or IVF/ICSI treatment cycle was unrelated to the number of binge drinking episodes in the month preceding baseline.

LIMITATIONS, REASONS FOR CAUTION

The risk of non-differential exposure misclassification, confounding, or chance cannot be ruled out. In addition, due to the low number of women reporting an intake of &gt;7 drinks/week, the potential effect of high alcohol consumption should be interpreted with caution.

WIDER IMPLICATIONS OF THE FINDINGS

Although it remains unsettled if and how alcohol affects female reproduction, our results indicate that is not necessary to abstain from alcohol when striving for a successful outcome following fertility treatment.

STUDY FUNDING/COMPETING INTEREST(S)

J.L. is supported by a fully financed Ph.D. scholarship from Aarhus University and has received funds from the A.P. Møller foundation. The funding sources had no involvement in the conduct of the article. Dr Kesmodel reports personal fees from MSD and Ferring Pharmaceuticals outside the submitted work. All other authors have no conflicts of interest to declare and all have completed the ICMJE disclosure form.

TRIAL REGISTRATION NUMBER

Not relevant.

Maternal age at menarche and pubertal development in sons and daughters: a Nationwide Cohort Study

STUDY QUESTION

Is maternal age at menarche associated with pubertal development in sons and daughters?

SUMMARY ANSWER

Maternal age at menarche was associated with pubertal development in both sons and daughters.

WHAT IS KNOWN ALREADY

Studies have shown that age at menarche is greatly inherited from mother to daughter, but it remains largely unknown to what extent age at menarche in mothers is associated with timing of puberty in sons.

STUDY DESIGN, SIZE, DURATION

In this population-based study we used data from the Puberty Cohort nested within the Danish National Birth Cohort. Live-born singletons aged 11 were followed from 2012 to 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 15 822 children (7697 sons and 8125 daughters) gave half-yearly information on puberty from the age of 11 years until full sexual maturity or 18 years of age through self-administrated questionnaires (participation rate 71%). Information on maternal age at menarche was reported by the mothers during pregnancy. Maternal age at menarche was used both as a continuous and as a categorical variable (earlier, same time or later than peers). A multivariable regression model for interval-censored data was used.

MAIN RESULTS AND THE ROLE OF CHANCE

Maternal age at menarche was positively associated with timing of genital development, pubic hair development, first ejaculation of semen, voice break, axillary hair development and acne in sons, and with timing of breast development, pubic hair development, menarche, axillary hair development and acne in daughters. In sons, the associations were of similar strength for all pubertal markers, whereas in daughters, the associations were strongest for breast development and menarche.

LIMITATIONS, REASONS FOR CAUTION

Age at menarche was recalled during pregnancy. However, studies indicate that age at menarche is recalled moderately in adulthood. Information on puberty was self-reported, but inaccuracy of data would probably cause non-differential misclassification.

WIDER IMPLICATIONS OF THE FINDINGS

Early maternal age at menarche was associated with earlier pubertal development, and late maternal age at menarche was associated with later pubertal development in both sons and daughters. The largest effect-estimates were for the associations between maternal age at menarche and the daughters' age at menarche and age at breast development.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Danish Council for Independent Research (4183-00152). There are no competing interests.

TRIAL REGISTERATION 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.

Maternal Smoking During Pregnancy and Timing of Puberty in Sons and Daughters: A Population-Based Cohort Study

Because early puberty has been linked to diseases later in life, identification of modifiable causes of early puberty is of interest. We explored the possible associations between maternal smoking during pregnancy and pubertal development in sons and daughters. Between 2012 and 2017, 15,819 children from the Danish National Birth Cohort, born during 2000-2003, provided half-yearly information on puberty from the age of 11 years. We estimated adjusted age differences (in months) at attaining various pubertal milestones, including Tanner stages, per 10 daily cigarettes smoked in the first trimester of gestation. In sons, exposure to smoking in utero was associated with earlier genital development (Tanner 2, -1.3 months, 95% confidence interval (CI): -2.5, 0.0; Tanner 5, -3.7 months, 95% CI: -5.3, -2.0), pubic hair development (Tanner 2, -1.8 months, 95% CI: -2.9, -0.6; Tanner 5, -2.9 months, 95% CI: -4.2, -1.7), and voice break (-2.4 months, 95% CI: -3.6, -1.3). In daughters, maternal smoking was associated with earlier breast development (Tanner 2, -3.4 months, 95% CI: -5.3, -1.5; Tanner 5, -4.7 months, 95% CI: -6.5, -2.9), pubic hair development stages 3-5 (Tanner 5, -2.5 months, 95% CI: -4.1, -1.0), and menarche (-3.1 months, 95% CI: -4.0, -2.3). Fetal exposure to tobacco smoke might advance timing of puberty in boys and girls.

Acetaminophen (Paracetamol) Exposure During Pregnancy and Pubertal Development in Boys and Girls From a Nationwide Puberty Cohort

This study explored the association between exposure to acetaminophen during pregnancy and pubertal development using data from 15,822 boys and girls in the longitudinal Puberty Cohort, nested within the Danish National Birth Cohort. Use of acetaminophen was reported 3 times during pregnancy and 6 months postpartum. In total, 54% of mothers indicated use at least once during pregnancy. Between 2012 and 2017, sons and daughters provided information on a wide range of pubertal milestones-including Tanner stages, axillary hair growth, and age at menarche or voice break and first ejaculation-every 6 months from 11 years of age until full sexual maturation. Data were analyzed using a regression model for interval-censored data, providing adjusted mean monthly differences in age at attaining the pubertal milestones according to intrauterine cumulative (weeks) and trimester-specific acetaminophen exposure. Our results suggested a tendency towards slightly earlier attainment of almost all studied markers of female pubertal development with increasing number of weeks of exposure (i.e., about 1.5-3 months earlier age at pubic hair, axillary hair, and acne development comparing unexposed with those prenatally exposed for more than 12 weeks). Male pubertal development had no strong association with acetaminophen exposure.

OFELIA: Prevalence of Osteoporosis in Fragility Fracture Patients

Worldwide, a care gap has been recognized between presenting with a fracture and prevention of the next fracture. Fracture Liaison Service is the most cost-effective method to close this gap, but its implementation is sparse in the Nordic countries. To assess the need for a fracture prevention program, the primary aim of this study was to estimate the prevalence of osteoporosis in patients treated for fragility fractures at Aarhus University Hospital, Denmark. Secondary aims were to identify clinical risk factors associated with osteoporosis and the up-take of anti-osteoporosis treatment. The study was conducted as a cross-sectional study and patients aged 18+ years were consecutively identified over a 12 months period. Of 1164 identified patients, 832 were included and 794 (70% women, 66% aged ≥ 50 years) patients completed the study. Bone mineral density was measured by DXA and information about clinical risk factors were obtained. The overall prevalence of osteoporosis in this cohort was 14.9%, increasing to 20.3% in patients ≥ 50 years (22.9% in women, 9.6% in men). In addition to age above 50 years, female sex, low BMI, and early menopause were significantly associated with osteoporosis. At 3-years follow-up in patients diagnosed with osteoporosis, 95% of patients who initiated anti-osteoporosis treatment after their fracture were still adherent to treatment. Given that osteoporosis was demonstrated in one in five fragility fracture patients above 50 years, OFELIA stresses the need for implementation of a program aiming at securing appropriate investigation and treatment of osteoporosis in patients presenting a fragility fracture.

Mental and behavioural disorders in the children of mothers diagnosed with cancer: A Danish population-based register study

OBJECTIVE

Maternal cancer may be associated with offspring mental and behavioural disorders through various biological pathways. When postnatally diagnosed, it may cause stress and changes in care, potentially influencing mental health. Prenatally diagnosed cancer could lead to maternal stress and treatment, or influence foetal neural development. This study investigates associations between prenatally or postnatally diagnosed maternal cancers and mental and behavioural disorders in children.

METHODS

The study composed of 2 158 430 children born in Denmark (1978-2012). Children were exposed if their mother received a cancer diagnosis prenatally (2 years prepartum, until birth) or postnatally (birth, until 18 years postpartum). Further analyses considered cancer types and diagnostic delays. Children were followed until 18 years of age or the first of the following: diagnosis of a mental or behavioural disorder, emigration, death, end of follow-up.

RESULTS

During follow-up 79 682 (3.7%) children were diagnosed with mental or behavioural disorders. There was an increased risk among offspring exposed to postnatally diagnosed cancers (HR 1.05; 95% CI, 1.00-1.11); for prenatally diagnosed cancers HR was 1.07 (0.87-1.31). The strongest associations for disorder types were for prenatal diagnoses with mood/affective disorders (HR 2.45; 1.02-5.89) and postnatal diagnoses with mood/affective disorders (HR 1.43; 1.14-1.79).

CONCLUSIONS

The results indicate a link between maternal cancer occurrence during pregnancy or early postnatal life, and mental and behavioural disorders in offspring. This association could be driven by common factors in the two periods, such as psychological stress or genetic factors. No specific foetal programming was identified.

Pregnancy-associated cancers and birth outcomes in children: a Danish and Swedish population-based register study

OBJECTIVES

This study aims to estimate the association between pregnancy-associated maternal cancers, diagnosed both prenatally and postnatally, and birth outcomes.

DESIGN

Population-based register study.

SETTING

National registers of Denmark and Sweden.

PARTICIPANTS

A total of 5 523 365 children born in Denmark (1977-2008) and Sweden (1973-2006).Primary and secondary outcome measures: gestational age, birth weight, size for gestational age, Apgar score, caesarean section and sex were the outcomes of interest. ORs and relative risk ratios (RRR) with 95% CIs were estimated using logistic regression and multinomial logistic regression, respectively.

RESULTS

In this study, 2% of children were born to mothers with a diagnosis of cancer. Children whose mothers received a prenatal cancer diagnosis had higher risk of being born preterm (RRR: 1.77, 95% CI 1.64 to 1.90); low birth weight (RRR 1.84, 95% CI 1.69 to 2.01); low Apgar score (OR 1.36, 95% CI 1.20 to 1.56); and by caesarean section (OR: 1.69, 95% CI 1.59 to 1.80). Associations moved towards the null for analyses using postnatal diagnoses, but preterm birth (RRR: 1.13, 95% CI 1.09 to 1.17) and low birth weight (RRR: 1.14, 95% CI 1.09 to 1.18) remained statistically significant, while risk of caesarean section became so (OR: 0.95, 95% CI 0.91 to 0.98). Additionally, statistical significance was reached for large for gestational age (RRR: 1.06, 95% CI 1.01 to 1.11), high birth weight (RRR: 1.04, 95% CI 1.01 to 1.06) and caesarean section (OR: 0.95, 95% CI 0.91 to 0.98).

CONCLUSIONS

Results suggest an association between pregnancy-associated cancers and adverse birth outcomes in the offspring. While this is strongest for prenatally diagnosed cancers, some smaller associations exist for postnatally diagnosed cancers, indicating that cancer itself could affect fetal development, or that cancer and adverse birth outcomes share risk factors. Future studies on maternal cancer during pregnancy should consider including some postnatal years in their exposure window.

Unrecognised coeliac disease among men and women undergoing fertility treatment: A screening study

BACKGROUND

Coeliac disease is an autoimmune disease triggered by dietary gluten and has been associated with several conditions influencing female and male reproduction. Due to unspecific symptoms, coeliac disease can be unrecognised for years.

OBJECTIVE

To estimate the prevalence of unrecognised coeliac disease among couples referred to fertility treatment.

METHODS

Cross-sectional screening for coeliac disease in men and women referred to fertility treatment using IgA tissue transglutaminase antibodies as a marker of coeliac disease and small-bowel biopsies to confirm the diagnosis. Participants answered a questionnaire on gluten intake, gastrointestinal symptoms and reproductive history.

RESULTS

A total of 893 participants (51% women) were screened and eight were coeliac disease antibody positive. Small-bowel biopsies were obtained from seven antibody positive participants and unrecognised coeliac disease was confirmed in one woman and three men, corresponding to a prevalence of 0.45% (95% confidence interval 0.12-1.14). The total prevalence, combining already diagnosed and unrecognised CD cases, was 0.63% (95% confidence interval 0.29-1.12).

CONCLUSION

The prevalence of unrecognised coeliac disease in a group of infertile patients was equivalent to that of the Danish general population and low compared with that observed in the majority of other screening studies of infertile patients. Surprisingly, it should be noted that more men than women had coeliac disease. This result does not support a need for routine screening among infertile patients.

Self-assessment of pubertal development in a puberty cohort

Background We evaluated the inter-rater agreement between self-assessed Tanner staging and clinical examination and the intra-individual agreement of self-assessed information on various puberty markers in late adolescents from the longitudinal nationwide Puberty Cohort, a sub-cohort of the Danish National Birth Cohort (DNBC). Methods We invited 715 children from the ongoing Puberty Cohort between June 2016 and January 2017. In total, 366 children (51%) returned an add-on questionnaire identical to the questionnaire used to collect information on puberty markers, including Tanner staging, in the Puberty Cohort. Of these, 197 (54%) also participated in a clinical examination with Tanner staging. We used percentage agreement and weighted kappa statistics to evaluate the inter-rater and intra-individual agreement. Results Due to late entry, more than 75% of children were Tanner stage 4 or above at clinical examination. In girls, the inter-rater agreement for pubic hair and breast staging was 54% and 52%, respectively, yielding weighted kappas of fair strength. In boys, pubic hair and genital staging agreed in 55% and 33%, respectively, corresponding to weighted kappas of fair to moderate strength. Boys tended to underestimate genitalia staging consistently. The intra-individual agreement on Tanner staging was 75-77% in girls and 69% in boys, whereas the intra-individual agreement on axillary hair and acne was above 92%. Conclusions Self-assessment of late stages of pubertal development may be misclassified, leading to random errors in studies of puberty timing. However, self-assessment continues to serve as an important time- and cost-saving tool in large prospective puberty cohorts.

Maternal diabetes mellitus and timing of pubertal development in daughters and sons: a nationwide cohort study

OBJECTIVE

To study the association between maternal diabetes and timing of pubertal development in daughters and sons.

DESIGN

Prospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 15,822 mother-child pairs included in the Danish National Birth Cohort and the Puberty Cohort with prospectively collected, register-based and self-reported information on maternal diabetes and self-reported information on pubertal development.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Adjusted mean monthly difference in age at attaining pubertal milestones in children born of mothers with diabetes compared with children born of mothers without diabetes.

RESULT(S)

A total of 502 children were born of mothers with diabetes during pregnancy. In daughters exposed to gestational diabetes mellitus, we observed advanced onset in all pubertal milestones. The associations were statistically significant with regard to pubic hair Tanner stage 2 (-4.8 months) (95% confidence interval [CI] -7.7, -2.0), pubic hair Tanner stage 3 (-2.2 months) (95 % CI -4.4, 0.0), pubic hair Tanner stage 5 (-6.0 months) (95% CI -10.8, -1.2), and menarche (-2.5 months) (95 % CI -4.9, 0.0). We observed no tendencies between maternal type 1 or type 2 diabetes mellitus and pubertal development in daughters. We observed no associations between maternal diabetes and pubertal development in sons.

CONCLUSION(S)

Our findings suggest that gestational diabetes mellitus may accelerate the pubertal development in daughters. Our results did not support an association between type 1 or type 2 diabetes mellitus and daughters' pubertal development, as well as between any type of maternal diabetes and sons' pubertal development.

Endometriosis and adenomyosis are associated with increased risk of preterm delivery and a small-for-gestational-age child: a systematic review and meta-analysis

INTRODUCTION

The objective of this systematic review and meta-analysis was to evaluate the risk of preterm delivery and having a small-for-gestational-age (SGA) child in women with endometriosis and adenomyosis compared with women without these two diseases.

MATERIAL AND METHODS

Studies on endometriosis or adenomyosis and risk of preterm delivery and/or SGA infant were included. The systematic search was conducted for all published articles in PubMed and Embase published from 1950 to 2017 using specific search terms. After duplicates were removed, two authors independently reviewed all studies, initially based on title and subsequently based on abstract. Studies considered relevant were read in full text by both reviewers to identify if studies met the inclusion criteria.

RESULTS

The search found 21 studies on a total of 2 517 516 women meeting the inclusion criteria. Women with endometriosis had an increased odds of preterm delivery [odds ratio (OR) 1.47, 95% CI 1.28-1.69] and SGA infant (OR 1.26, 95% CI 1.04-1.549). Compared with endometriosis, adenomyosis implied an even higher odds of both preterm delivery (OR 3.09, 95% CI 1.88-5.09) and SGA infant (OR 3.23, 95% CI 1.71-6.09) as well.

CONCLUSIONS

Women with endometriosis or adenomyosis had a higher odds of preterm delivery and having a child that was SGA compared with women without endometriosis or adenomyosis. The odds of both adverse birth outcomes was highest among women with adenomyosis. The results suggest a closer prenatal monitoring among pregnant women with endometriosis or adenomyosis.

Noise-Induced Hearing Loss - A Preventable Disease? Results of a 10-Year Longitudinal Study of Workers Exposed to Occupational Noise

Aims:

To survey current, Danish industrial noise levels and the use of hearing protection devices (HPD) over a 10-year period and to characterise the association between occupational noise and hearing threshold shift in the same period. Furthermore, the risk of hearing loss among the baseline and the follow-up populations according to first year of occupational noise exposure is evaluated.

Materials and Methods:

In 2001–2003, we conducted a baseline survey of noise- and hearing-related disorders in 11 industries with suspected high noise levels. In 2009–2010, we were able to follow up on 271 out of the 554 baseline workers (49%). Mean noise levels per industry and self-reported HPD use are described at baseline and follow-up. The association between cumulative occupational noise exposure and hearing threshold shift over the 10-year period was assessed using linear regression, and the risk of hearing loss according to year of first occupational noise exposure was evaluated with logistic regression.

Results:

Over the 10-year period, mean noise levels declined from 83.9 dB(A) to 82.8 dB(A), and for workers exposed >85 dB(A), the use of HPD increased from 70.1 to 76.1%. We found a weak, statistically insignificant, inverse association between higher ambient cumulative noise exposure and poorer hearing (−0.10 dB hearing threshold shift per dB-year (95% confidence interval (CI): −0.36; 0.16)). The risk of hearing loss seemed to increase with earlier first year of noise exposure, but odds ratios were only statistically significant among baseline participants with first exposure before the 1980s (odds ratio: 1.90, 95% CI: 1.11; 3.22).

Conclusions:

We observed declining industrial noise levels, increased use of HPD and no significant impact on hearing thresholds from current ambient industrial noise levels, which indicated a successful implementation of Danish hearing conservation programs.

Is age at puberty associated with semen quality and reproductive hormones in young adult life?

The evidence is scarce on the association between age at puberty and semen quality. A cohort of 320 Danish men aged 18-21 years enrolled in the "Healthy Habits for Two" birth cohort provided self-reported data on pubertal indicators and delivered semen and blood samples. The results indicated an association between older age at pubertal development and lower semen quality and altered reproductive hormones concentrations as measured in young adult life. Men who had their first nocturnal emission, start of pubic hair growth and first voice break episode when older than 15 years had 37.0%, 45.0% and 32.7% lower sperm concentration; 37.8%, 44.2% and 29.1% lower total sperm count; 7.4%, 13.4% and 15.3% lower testosterone concentration; and 21.3%, 1.5% and 3.7% lower inhibin B concentration, respectively, compared with the men who were younger than 13 years at their first pubertal indicators. Only few of the results were statistically significant, but similar tendencies were seen in several of the reproductive parameters suggesting an association between the timing of pubertal development and reproductive health later in life.

Use of non-prescription analgesics and male reproductive function

We studied the association between intake of non-prescription analgesics and semen quality and male reproductive hormone levels in a cross-sectional study among 1493 men. The men provided one semen (n=1493) and blood sample (n=1056) and filled in questionnaires on use of non-prescription analgesics (paracetamol, NSAIDs and combination drugs (yes/no)). Adjusting for age, study and other covariates, we observed no association between intake of non-prescription analgesics and markers of semen quality. Adjusting for age and time of day of blood sampling, users of non-prescription analgesics had a 10.4% (95% confidence interval (CI) 4.0-17.1%) higher testosterone level than non-users. When we stratified by medication type, the association between analgesics and higher testosterone was observed between users of non-steroidal anti-inflammatory drugs (NSAIDs) and combination drugs but not paracetamol. This study suggests that use of non-prescription analgesics is associated with slightly higher serum testosterone levels than non-use.

Informal caregiving as a risk factor for type 2 diabetes in individuals with favourable and unfavourable psychosocial work environments: A longitudinal multi-cohort study

AIM

To examine whether informal caregiving is associated with increased risk of type 2 diabetes (T2D), and whether job strain and social support at work modify the association.

METHODS

Individual participant's data were pooled from three cohort studies-the French GAZEL study, the Swedish Longitudinal Occupational Survey of Health (SLOSH) and the British Whitehall II study-a total of 21,243 study subjects. Informal caregiving was defined as unpaid care for a closely related person. Job strain was assessed using the demand-control model, and questions on co-worker and supervisor support were combined in a measure of social support at work. Incident T2D was ascertained using registry-based, clinically assessed and self-reported data.

RESULTS

A total of 1058 participants developed T2D during the up to 10 years of follow-up. Neither informal caregiving (OR: 1.09, 95% CI: 0.92-1.30) nor high job strain (OR: 1.04, 95% CI: 0.86-1.26) were associated with T2D risk, whereas low social support at work was a risk factor for T2D (OR: 1.18, 95% CI: 1.02-1.37). Also, informal caregivers who were also exposed to low social support at work were at higher risk of T2D (OR: 1.40, 95% CI: 1.08-1.82) compared with those who were not informal caregivers and had high social support at work (multiplicative test for interaction, P=0.04; additive test for interaction, synergy index=10).

CONCLUSION

Informal caregiving was not independently associated with T2D risk. However, low social support at work was a risk factor, and informal caregivers with low social support at work had even higher risks of T2D.

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.

Comparison of nurse practice environments in Denmark and the USA

AIMS

The aims were to translate, validate and test the reliability of the Practice Environment Scale of the Nursing Work Index in a Danish context; and to compare Danish nurses' ratings of their nurse work environments with the highest rated work environments, USA magnet hospitals.

BACKGROUND

Patient quality and safety are priorities for managers, administrators and policy makers worldwide. A supportive work environment is an important factor to improve quality and safety. The most used scale to measure the nurse work environment is Practice Environment Scale of the Nursing Work Index. There is no Danish translation of the scale or a comparison of nurse work environment between Denmark and other countries.

METHODS

The translation and cultural adaption followed the steps recommended by the World Health Organization. Content validity was evaluated using cognitive interviewing in-person and through surveys. The reliability was tested using Cronbach's alpha. Finally, Practice Environment Scale of the Nursing Work Index ratings from 127 nurses were compared with results from Magnet and non-Magnet hospitals using t-tests.

FINDINGS

The Danish translation of Practice Environment Scale of the Nursing Work Index had a high validity and reliability. Danish nurses rated their nurse work environment more favourable than nurses in non-Magnet hospitals and at the same level as Magnet hospitals. Lowest Danish scores were found in the two hospital-level subscales in items related to staff nurses' involvement in discussions on daily problems, the visibility of the chief nursing officer and importance of up-to-date nursing documentation.

CONCLUSION

Danish nurses report a supportive nurse work environment with overall scores at the same level as Magnet hospitals. Opportunities for improvement were identified in the subscales.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

A first step to improve patient quality and safety is addressing factors that influence quality and safety. Using the Danish Practice Environment Scale of the Nursing Work Index, interventions to improve specific areas can be planned, implemented and evaluated. Further, Practice Environment Scale of the Nursing Work Index is a nursing quality indicator that can be included in quality databases in Denmark.

In utero exposure to persistent organochlorine pollutants and reproductive health in the human male

Persistent organochlorine pollutants (POPs) are ubiquitous, bioaccumulative compounds with potential endocrine-disrupting effects. They cross the placental barrier thereby resulting in in utero exposure of the developing fetus. The objective of this study was to investigate whether maternal serum concentrations of polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) during pregnancy are associated with son's semen quality and reproductive hormone levels. During 2008-2009, we recruited 176 male offspring from a Danish cohort of pregnant women who participated in a study in 1988-1989. Each provided semen and blood samples that were analyzed for sperm concentration, total sperm count, motility, and morphology, and reproductive hormone levels, respectively. The maternal blood samples were collected in pregnancy week 30 and were analyzed for the concentrations of six PCBs (PCB-118, -138, -153, -156, -170, and -180) and p,p'-DDE. The potential associations between in utero exposure to ΣPCBs (pmol/ml), Σdioxin like-(DL) PCBs (PCB-118 and -156) (pmol/ml), and p,p'-DDE and semen quality and reproductive hormone levels were investigated using multiple regression. Maternal median (range) exposure levels of ΣPCB, ΣDL-PCB, and p,p'-DDE were 10.0 (2.1-35.0) pmol/ml, 0.8 (0.2-2.7) pmol/ml, and 8.0 (0.7-55.3) pmol/ml, respectively, reflecting typical background exposure levels in the late 1980s in Denmark. Results suggested that in utero exposure to ΣPCB, ΣDL-PCB, and p,p'-DDE was not statistically significantly associated with semen quality measures or reproductive hormone levels. Thus, results based on maternal PCB and p,p'-DDE concentrations alone are not indicative of long-term consequences for male reproductive health; however, we cannot exclude that these POPs in concert with other endocrine-modulating compounds may have adverse effects.

Maternal cigarette smoking during pregnancy and pubertal development in sons. A follow-up study of a birth cohort

Epidemiological studies have raised concern about the reproductive consequences of prenatal cigarette smoking exposure, possibly affecting semen quality and onset of pubertal development of the offspring. The aim of this study was to further investigate pubertal development in young men exposed to cigarette smoking in foetal life. In a Danish pregnancy cohort, information on maternal smoking during pregnancy was available from questionnaires administered in 1984-1987, and information on pubertal development, assessed by age at first nocturnal emission, acne, voice break and regular shaving, was obtained from a follow-up questionnaire administered in 2005 to the young men (age: 18-21). We found no significant association between prenatal cigarette smoking exposure and earlier onset of puberty, but we did observe a tendency towards earlier age of first nocturnal emission, acne and voice break, indicating an accelerated age of pubertal development. Men exposed to ≥15 cigarettes/day had 3.1 months (95% CI: -6.4; 0.2) earlier age at acne and 2.2 months (95% CI: -7.3; 3.0) earlier age at first nocturnal emission, 1.2 months (95% CI: -4.6; 2.2) earlier age at voice break, however, 1.3 months (95% CI: -1.6; 4.3) later age at regular shaving, compared with unexposed men. Prenatal cigarette smoking exposure may induce an earlier age at onset of puberty in young men, but larger studies with prospectively collected data on pubertal development are needed to explore this hypothesis further.

BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis

BACKGROUND The global obesity epidemic has paralleled a decrease in semen quality. Yet, the association between obesity and sperm parameters remains controversial. The purpose of this report was to update the evidence on the association between BMI and sperm count through a systematic review with meta-analysis. METHODS A systematic review of available literature (with no language restriction) was performed to investigate the impact of BMI on sperm count. Relevant studies published until June 2012 were identified from a Pubmed and EMBASE search. We also included unpublished data (n = 717 men) obtained from the Infertility Center of Bondy, France. Abstracts of relevant articles were examined and studies that could be included in this review were retrieved. Authors of relevant studies for the meta-analysis were contacted by email and asked to provide standardized data. RESULTS A total of 21 studies were included in the meta-analysis, resulting in a sample of 13 077 men from the general population and attending fertility clinics. Data were stratified according to the total sperm count as normozoospermia, oligozoospermia and azoospermia. Standardized weighted mean differences in sperm concentration did not differ significantly across BMI categories. There was a J-shaped relationship between BMI categories and risk of oligozoospermia or azoospermia. Compared with men of normal weight, the odds ratio (95% confidence interval) for oligozoospermia or azoospermia was 1.15 (0.93-1.43) for underweight, 1.11 (1.01-1.21) for overweight, 1.28 (1.06-1.55) for obese and 2.04 (1.59-2.62) for morbidly obese men. CONCLUSIONS Overweight and obesity were associated with an increased prevalence of azoospermia or oligozoospermia. The main limitation of this report is that studied populations varied, with men recruited from both the general population and infertile couples. Whether weight normalization could improve sperm parameters should be evaluated further.

Maternal smoking during pregnancy and reproductive health of daughters: a follow-up study spanning two decades

STUDY QUESTION

Does in utero exposure to constituents of cigarette smoke have a programming effect on daughters' age of menarche and markers of long-term reproductive health?

SUMMARY ANSWER

In utero exposure to constituents of cigarette smoke was associated with earlier age of menarche and--to a lesser extent--changes in the testosterone profile of the young women.

WHAT IS KNOWN ALREADY

Studies observe potential effects of in utero exposure to constituents of cigarette smoke on the intrauterine formation of female gonads, but the consequences on long-term reproductive health in daughters remain unclear.

STUDY DESIGN, SIZE AND DURATION

A prospective cohort study was designed using data from 965 pregnant women enrolled prior to a routine 30th-week antenatal examination at a midwifery practice in Denmark from 1988 to 1989 and a follow-up of their 19-21-year-old daughters in 2008.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

The pregnant women provided information on lifestyle factors during pregnancy, including the exact number of cigarettes smoked per day during the first and the second trimesters. A total of 438 eligible daughters were asked to complete a web-based questionnaire on reproductive health and subsequently invited to participate in a clinical examination during 2008. Of the 367 daughters (84%) who answered the questionnaire, 267 (61%) agreed to further examination. Information on menstrual pattern was provided at examination, blood samples were drawn to be analyzed for serum levels of reproductive hormones [FSH, LH, estradiol (E(2)), sex hormone-binding globulin, anti-Müllerian hormone, dehydroepiandrosterone-sulphate (DHEAS), free testosterone and free E(2)] and number of follicles (2-9 mm) were examined by transvaginal ultrasound. The daughters were divided into three exposure groups according to the level of maternal smoking during first trimester [non-exposed (reference), low-exposed (mother smoking >0-9 cigarettes/day) and high-exposed (mother smoking ≥ 10 cigarettes/day)]. Data were analyzed by multiple regression analyses in which we adjusted for potential confounders. Both crude and adjusted test for trend were carried out using maternal smoking during the first trimester as a continuous variable.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed an inverse association between in utero exposure to constituents of cigarette smoke and age of menarche (P = 0.001). Daughters exposed to >0-9 cigarettes/day debuted with -2.7 [95% confidence interval (CI) -5.2 to -0.1] percentage earlier age of menarche, whereas daughters exposed to ≥ 10 cigarettes/day had -4.1 (95% CI: -6.6 to -1.5) percentage earlier age of menarche corresponding to 6.5 (95% CI: -10.7 to -2.2) months. There was a non-significant tendency towards lower levels of testosterone and DHEAS with increasing in utero exposure to constituents of cigarette smoke but no associations with follicle number, cycle length or serum levels of the other reproductive hormones were observed.

LIMITATIONS AND REASONS FOR CAUTION

We collected information on age of menarche retrospectively but the recall time was relatively short (2-10 years) and the reported values were within the normal range of Caucasians. Analyses of reproductive hormones are presented only for the group of daughters who were non-users of hormonal contraceptives because users were excluded, leaving only a low number of daughters available for the analyses (n = 75), as reflected in the wide CIs. The analyses of hormones were further adjusted for menstrual phase at time of clinical examination (follicular, ovulation and luteal phase) because blood samples were not collected on a specific day of the menstrual cycle.

WIDER IMPLICATIONS OF THE FINDINGS

This study supports the limited evidence of an inverse association between maternal smoking during pregnancy and age of menarche and further addresses to what extent reproductive capacity and hormones may be programmed by maternal smoking during pregnancy. A trend toward earlier maturation of females is suggested to have implications on long-term reproductive function.

STUDY FUNDING/COMPETING INTEREST(S)

Supported by a scholarship from The Lundbeck Foundation (R93-A8476). No conflict of interest declared.

Male-mediated infertility in sons of building painters and gardeners: a nationwide register-based follow-up study

AIM

To investigate whether sons of gardeners and building painters have increased risk of infertility in comparison with sons of bricklayers, carpenters and electricians.

METHODS

Participants were men born 1965-1984 in Denmark whose fathers the year before birth had worked as gardeners, painters, bricklayers, carpenters or electricians (N=22,978). Cases of infertility were identified by Danish registers, and participants were followed-up for up to 24 years after their 20th birthday.

RESULTS

Sons of gardeners did not have increased risk of infertility. Hazard ratios for sons of painters fluctuated around the null in main analyses but were 1.6 (98% CI: 1.0-2.5) and 1.7 (95% CI: 0.9-3.2) in the subset of participants with smallest risk of paternal exposure misclassification.

CONCLUSIONS

Working as gardener or building painter was not related to increased risk of infertility among the next generation of males in main analyses. However, inherent limitations in data may have attenuated true associations.

Does last week's alcohol intake affect semen quality or reproductive hormones? A cross-sectional study among healthy young Danish men

The association between last 5 days of alcohol intake, semen quality and reproductive hormones was estimated in this cross-sectional study among 347 men. Conventional semen characteristics, DNA fragmentation index and reproductive hormones (testosterone, estradiol, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and inhibin B) were determined. There was a tendency towards lower semen characteristics at higher intake of alcohol past 5 days, albeit with no statistically significant dose-response association. The ratio between free estradiol and free testosterone was higher at higher alcohol intake during the 5 days preceding semen sampling. In conclusion, alcohol intake was associated with impairment of most semen characteristics but without a coherent dose-response pattern. The study indicates an association between recent alcohol intake and a hormonal shift towards higher estradiol/testosterone ratio. The hormonal changes observed may over time, lead to adverse effects on semen quality, but longitudinal studies are needed to study this.

A comparison of conventional and computer-assisted semen analysis (CRISMAS software) using samples from 166 young Danish men

The aim of the present study was to compare assessments of sperm concentration and sperm motility analysed by conventional semen analysis with those obtained by computer-assisted semen analysis (CASA) (Copenhagen Rigshospitalet Image House Sperm Motility Analysis System (CRISMAS) 4.6 software) using semen samples from 166 young Danish men. The CRISMAS software identifies sperm concentration and classifies spermatozoa into three motility categories. To enable comparison of the two methods, the four motility stages obtained by conventional semen analysis were, based on their velocity classifications, divided into three stages, comparable to the three CRISMAS motility categories: rapidly progressive (A), slowly progressive (B) and non-progressive (C+D). Differences between the two methods were large for all investigated parameters (P < 0.001). CRISMAS overestimated sperm concentration and the proportion of rapidly progressive spermatozoa and, consequently, underestimated the percentages of slowly progressive and non-progressive spermatozoa, compared to the conventional method. To investigate whether results drifted according to time of semen analysis, results were pooled into quarters according to date of semen analysis. CRISMAS motility results appeared more stable over time compared to the conventional analysis; however, neither method showed any trends. Apparently, CRISMAS CASA results and results from the conventional method were not comparable with respect to sperm concentration and motility analysis. This needs to be accounted for in clinics using this software and in studies of determinants of these semen characteristics.

Has fertility declined in recent decades?

OBJECTIVE

Increasing use of infertility treatment and a decline in demographic fertility in some countries have raised concern whether human fecundity is declining or has declined over time. A dramatic decline in semen quality over the past half-century has been proposed and widely discussed, but none of the existing studies provide data good enough for coming to any firm conclusion.

RESULTS

Results from 19 articles published during the last 5 years on semen quality and fecundity, covering data from the Nordic countries since the year 2000, do not indicate an ongoing decline in fertility.

CONCLUSION

We will probably never know, whether semen quality and fecundity has declined over time, but we may be able to monitor biological fecundity and semen quality over time from now on. There are both research initiatives and interest from official channels that could provide more funding for infertility research.