The current 'dramatically' high paternal ages at childbirth are not unprecedented.

There is strong individual-level evidence that late fatherhood is related to a wide range of health disorders and conditions in offspring. Over the last decades, mean paternal ages at childbirth have risen drastically. This has alarmed researchers from a wide range of fields. However, existing studies have an important shortcoming in that they lack a long-term perspective. This article is a step change in providing such a long-term perspective. We unveil that in many countries the current mean paternal ages at childbirth and proportions of fathers of advanced age at childbirth are not unprecedented. Taking the detected U-shaped trend pattern into account, we discuss individual- and population-level implications of the recent increases in paternal ages at childbirth and highlight important knowledge gaps. At the individual level, some of the biological mechanisms that are responsible for the paternal age-related health risk might, at least to some degree, be counterbalanced by various social factors. Further, how these individual-level effects are linked to population health and human cognitive development might be influenced by various factors, including technical advances and regulations in prenatal diagnostics.

Socioeconomic position and prediagnostic health care contacts in children with cancer in Denmark: a nationwide register study.

BACKGROUND: While underlying mechanisms and pathways of social inequalities in cancer survival have been extensively examined in adults, this is less so for children with cancer. Hypothesized mechanisms include prediagnostic utilization of and navigation through the health care system, which may differ by socioeconomic resources of the families. In this nationwide register-based study we investigated the association between measures of family socioeconomic position in relation to prediagnostic health care contacts and stage of disease at diagnosis in children with cancer in Denmark. METHODS: We identified all children diagnosed with a cancer at ages 0-15 years in 1998-2016 (N = 3043) from the Danish Childhood Cancer Registry. We obtained comprehensive information on measures of socioeconomic position, parental health and prediagnostic contacts to both general practitioners and hospitals 24 months prior to diagnosis from various national registries. We fitted multivariable conditional logistic regression models for the association of family socioeconomic and health-related variables with firstly, frequent health care contacts and secondly, advanced stage. RESULTS: We found higher odds ratios (OR) of frequent both overall and emergency health care contacts in the last 3 months before diagnosis in children from households with short parental education and mixed affiliation to work market, when compared to children with high family socioeconomic position. Further, children of parents with depression or of non-Western origin, respectively, had higher OR for frequent overall and emergency contacts. We found no association between socioeconomic position, parental health and stage of disease. CONCLUSION: Families with socioeconomic disadvantage, non-Western origin or depression more frequently utilize prediagnostic health care services, both generally and in the acute setting, indicating that some disadvantaged families may struggle to navigate the health care system when their child is sick. Reassuringly, this was not reflected in disparities in stage at diagnosis. In order to improve the diagnostic process and potentially reduce health care contacts, attention and support should be given to families with a high number of health care contacts over a short period of time.

Social, demographic and health characteristics of men fathering children at different ages.

The aim of this study was to examine associations between selected sociodemographic, socioeconomic, and health characteristics and the rates of fatherhood in different age groups. We investigated rates between 2011 and 2015 in a population-based register study including all men born from 1945 to 1995 residing in Denmark in 2011. The study population consisted of 1,867,108 men who fathered 268,612 children during the follow-up. The associations were quantified as incidence rate ratios using Poisson regression. Young men had higher rates of fathering a child if they lived outside the Capital Region, had a relatively high income, were previously diagnosed with cardiovascular disease, psychoactive substance abuse, personality disorders, schizophrenia or behavioural and emotional disorders. Men of advanced age had higher rates of fathering a child when born outside Denmark, living in the Capital Region, were in the lower or upper 10th percentile income group, were self-employed or unemployed or previously diagnosed with depression. Men of advanced age had lower rates of fathering a child if previously diagnosed with somatic diseases, psychoactive substance abuse or mental retardation. The findings highlight the importance of consideration of various sociodemographic, socioeconomic, and health characteristics when studying associations between paternal age and offspring health.

A single center experience with publicly funded clinical exome sequencing for neurodevelopmental disorders or multiple congenital anomalies.

Exome sequencing (ES) is an important diagnostic tool for individuals with neurodevelopmental disorders (NDD) and/or multiple congenital anomalies (MCA). However, the cost of ES limits the test's accessibility for many patients. We evaluated the yield of publicly funded clinical ES, performed at a tertiary center in Israel, over a 3-year period (2018-2020). Probands presented with (1) moderate-to-profound global developmental delay (GDD)/intellectual disability (ID); or (2) mild GDD/ID with epilepsy or congenital anomaly; and/or (3) MCA. Subjects with normal chromosomal microarray analysis who met inclusion criteria were included, totaling 280 consecutive cases. Trio ES (proband and parents) was the default option. In 252 cases (90.0%), indication of NDD was noted. Most probands were males (62.9%), and their mean age at ES submission was 9.3 years (range 1 month to 51 years). Molecular diagnosis was reached in 109 probands (38.9%), mainly due to de novo variants (91/109, 83.5%). Disease-causing variants were identified in 92 genes, 15 of which were implicated in more than a single case. Male sex, families with multiple-affected members and premature birth were significantly associated with lower ES yield (p < 0.05). Other factors, including MCA and coexistence of epilepsy, autism spectrum disorder, microcephaly or abnormal brain magnetic resonance imaging findings, were not associated with the yield. To conclude, our findings support the utility of clinical ES in a real-world setting, as part of a publicly funded genetic workup for individuals with GDD/ID and/or MCA.

One size does not fit all: variations by ethnicity in demographic characteristics of men seeking fertility treatment across North America.

OBJECTIVE: To compare racial differences in male fertility history and treatment. DESIGN: Retrospective review of prospectively collected data. SETTING: North American reproductive urology centers. PATIENT(S): Males undergoing urologist fertility evaluation. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Demographic and reproductive Andrology Research Consortium data. RESULT(S): The racial breakdown of 6,462 men was: 51% White, 20% Asian/Indo-Canadian/Indo-American, 6% Black, 1% Indian/Native, <1% Native Hawaiian/Other Pacific Islander, and 21% "Other". White males sought evaluation sooner (3.5 ± 4.7 vs. 3.8 ± 4.2 years), had older partners (33.3 ± 4.9 vs. 32.9 ± 5.2 years), and more had undergone vasectomy (8.4% vs. 2.9%) vs. all other races. Black males were older (38.0 ± 8.1 vs. 36.5 ± 7.4 years), sought fertility evaluation later (4.8 ± 5.1 vs. 3.6 ± 4.4 years), fewer had undergone vasectomy (3.3% vs. 5.9%), and fewer had partners who underwent intrauterine insemination (8.2% vs. 12.6%) compared with all other races. Asian/Indo-Canadian/Indo-American patients were younger (36.1 ± 7.2 vs. 36.7 ± 7.6 years), fewer had undergone vasectomy (1.2% vs. 6.9%), and more had partners who underwent intrauterine insemination (14.2% vs. 11.9%). Indian/Native males sought evaluation later (5.1 ± 6.8 vs. 3.6 ± 4.4 years) and more had undergone vasectomy (13.4% vs. 5.7%). CONCLUSION(S): Racial differences exist for males undergoing fertility evaluation by a reproductive urologist. Better understanding of these differences in history in conjunction with societal and biologic factors can guide personalized care, as well as help to better understand and address disparities in access to fertility evaluation and treatment.

"I have to provide for another life emotionally, physically and financially": understanding pregnancy, motherhood and the future aspirations of adolescent mothers in KwaZulu-Natal South, Africa.

BACKGROUND: Adolescent pregnancy and motherhood has been a controversial and much disputed subject within the field of public health. Early childbearing is not only characterized as a physical body experience but also embodies the experiences and perceptions of the social norms, discourses, conflict and moral judgement. There is an increasing concern that the psychosocial challenges facing adolescent mothers remains in the background since research in this field has mainly focused on the medical and physical complications of early childbearing. The aim of this qualitative study was to explore adolescent pregnancy and motherhood in order to understand this phenomenon from the perspective of adolescent mothers and to gain insight into their future aspirations. METHODS: This descriptive qualitative study was based on data from four focus group discussions with adolescent mothers utilising healthcare services at a district hospital in Ugu district, KwaZulu Natal, South Africa. The data were audio-recorded and transcribed verbatim, then analysed using thematic analysis. RESULTS: Some adolescent mothers' partners were in denial and rejected them and the child while others' partners were happy and supported them during their pregnancy. Families' reactions to the pregnancies ranged between anger and disappointment to abandonment, the silent treatment, and acceptance and forgiveness. The psychological issues experienced by some of the adolescent mothers included suicidal ideation, guilt, loneliness, anxiety, and stress. They also experienced financial constraints, difficulty in returning to school, and stigmatisation in society. The participants envisioned completing their education, focusing on their dream careers, and contributing positively to society. CONCLUSION: Experiences of adolescent pregnancy and parenting are multifaceted and the healthcare needs of pregnant and parenting adolescents extend beyond information and knowledge. A multidisciplinary approach is required in the care of adolescent mothers. A key policy priority should encompass the collaboration of different professionals from various healthcare sectors to assist adolescent mothers in achieving better health and psychosocial and socio-economic outcomes as steps to securing a better future for them.

Telomere length in early childhood is associated with sex and ethnicity.

Telomeres are repetitive DNA sequences at the end of chromosomes that function to protect chromosomes from degradation. Throughout the life course, telomere length decreases with age and is influenced by environmental factors and health conditions. This study aimed to determine the relative telomere lengths in a diverse cohort of about 4000 four-year-old children in New Zealand. Linear regression was used to investigate the relationship between telomere length, child gender, ethnicity, paternal age and deprivation. We observed substantial variation in telomere length according to sex and self-identified ethnicity. Telomere length was longer in females compared to males (coefficient of 0.042, 95% confidence interval (CI) 0.024-0.060). European children had shorter telomere than both the indigenous Maori (coefficient of 0.03, CI 0.007-0.055) and Pacific children (coefficient of 0.15, CI 0.12-0.18). The data suggest that telomere lengths are highly variable and variability between individuals arise from early age, influenced partly by sex and ethnicity. Longer telomeres in indigenous Maori and Pacific children may reflect the heritability of telomere length in genetically less complex populations. This study increases our understanding of telomere dynamics in young children since the majority of telomere studies are conducted in adults.

The association between socioeconomic status, duration of breastfeeding, parental age and birth parameters with BMI, body fat and muscle mass among prepubertal children in Poland.

Objectives: We aimed to indicate simple determinants of abnormal body composition in children, such as socio-economic status (SES), duration of breastfeeding, parental age and birth parameters. Methods: The final data set consisted of 469 healthy prepubertal individuals (247 girls and 222 boys). We studied body mass, body height, and parameters of body composition such as muscle mass and fat mass. The birth parameters and gestational age were obtained from the children's medical record books held by the parents which were completed by medical personnel immediately following birth. Information about socio-economic status (SES), duration of breastfeeding and parental age was obtained by questionnaire. The statistical methods included forward multiple regression and generalized linear models (GLZ) or general linear model (GLM). Results: Higher fat mass (FM) (%) was connected with shorter duration of breastfeeding (< 2 months and lower SES (p < 0.05). Lower muscle mass (MM) (%) was linked with lower SES (p < 0.05) and lower birth weight (p < 0.05). Higher body mass index (BMI) was connected with higher birth weight (p < 0.05), shorter duration of breastfeeding (< 2 months) and lower SES (p < 0.05). Moreover interaction effects were observed in the case of the FM (%) (breastfeeding x SES; breastfeeding x parental age) and the BMI (breastfeeding x paternal age). Conclusions: Body composition can be linked with the duration of breastfeeding, SES, parental age, birth weight and birth length.

Additive Contributions of Social Information Processing and Economic Stress to Maltreatment Risk in Disadvantaged Rural Fathers.

Child maltreatment is a critical concern in rural communities. Fathers perpetrate a substantial proportion of maltreatment cases and are overrepresented as perpetrators of severe physical abuse and fatalities. Despite this heightened risk, little research has examined risk of abuse and neglect among fathers in rural areas. The current study examined the contributions of social information processing (SIP) factors and economic stress to multiple indicators of maltreatment risk in a sample of 61 disadvantaged rural fathers of 2- to 6-year-old children. Results for the SIP model of maltreatment risk provide some support for its extension to fathers. Considered all together, SIP factors were associated with more inconsistent parenting and maladaptive injury prevention beliefs. Specific SIP factors of unrealistic expectations for children and poorer executive functioning were associated with more maladaptive injury prevention beliefs. With regard to economic stress, fewer economic resources were associated with greater child abuse potential, more inconsistent parenting, and poorer quality home environments, while less economic security was associated with greater child abuse potential. Analyses found evidence for independent additive effects of SIP and economic stress. Findings highlight the importance of fathers' cognition and economic stress in children's risk of physical abuse, neglect, and unintentional injuries.

Patterns and predictors of depressive symptoms among Jamaican fathers of newborns.

BACKGROUND: Approximately 10% of fathers in the Cultural West (i.e., US, Europe, and Australia) experience depression. We broaden the cultural scope of paternal depression research by investigating the prevalence and predictors of depressive symptoms among Jamaican fathers. METHODS: The present research draws upon structured interviews with 3425 fathers of newborn children participating in a Jamaican birth cohort study-JA Kids-and represents one of the largest sample sizes of any study on postnatal depression among fathers worldwide. This sample of fathers participated from July to September 2011, and represents approximately 30% of all men who became fathers during that time in Jamaica. Fathers answered questions about sociodemographic background, relationship status and quality, social support, health, expectations and views of a partner's pregnancy, and the ten-item Edinburgh Postnatal Depression Scale (EPDS). RESULTS: Analyses reveal that 9.1% (95% CI 8.1-10.1) of these Jamaican fathers of newborns had EPDS scores of 10 or higher, indicative of possible depression. Results suggest that educational attainment was not related to EPDS scores, though higher indices of material wealth (e.g., refrigerator and vehicle) were weakly, negatively related to EDS scores. Paternal age was also weakly negatively predictive of EDS scores. Whereas relationship status was unrelated to depressive symptoms, relationship quality negatively predicted depressive symptoms. Several other measures of social support (lacking a close circle of friends, fewer family, or friends to help in times of trouble) were also associated with higher EPDS scores. CONCLUSIONS: We interpret these findings in light of existing work on paternal depression, including the importance of social context and support.

Life-Course Relationship between Socioeconomic Circumstances and Timing of First Birth in a Birth Cohort.

OBJECTIVES: This study examines the influence of socioeconomic circumstances in childhood (childhood SES) and adulthood (adult SES) on timing of first birth by age 37. METHODS: A longitudinal study of a 1972-1973 New Zealand birth cohort collected information on socioeconomic characteristics from age 3-32 and reproductive histories at 21, 26, 32 and 38; information on first birth was available from 978 of the original 1037. Relative Risks (RR) and 95% Confidence Intervals (CI) were calculated using Poisson regression to examine first live birth prior to age 21, from 21-25, from 26-31, and from 32-37, by socioeconomic characteristics at different ages. RESULTS: Overall, 68.5% of men had fathered a child and 75.9% of women had given birth, by age 37; with overall differences in parenthood to age 31 for men, and 37 for women evident by childhood SES. While parenthood by age 20 was strongly associated with lower childhood SES for both sexes, first entry into motherhood from 32-37 was more likely with higher adult SES at age 32 (RR = 1.8, 95% CI 1.1-3.0 for medium and RR = 1.9, 95% CI 1.1-3.3 for high compared with low). Education also differientated age at parenthood, with those with higher education more likely to defer fatherhood past age 31, and motherhood past age 25 followed by a period of increased likelihood of motherhood for women with higher levels of education from age 32-37 (RR = 1.4, 95% CI 0.87-2.2 and RR = 1.7, 95% CI 1.1-2.6 for medium and high respectively compared with low). CONCLUSIONS: SES varies across the lifecourse, and SES at the time has the strongest association with first births at that time. Low childhood SES drives adolescent parenthood, with resulting cumulative differences in parenthood past age 30. Those with more education and higher adult SES are deferring parenthood but attempt to catch up in the mid to late thirties.

Delayed parenthood on the rise: A call for upstream preconception health promotion in Canada.

The trend toward delayed parenthood is on the rise across Canada. Societal emphasis on attaining higher education, career advancement and financial security may be some reasons why individuals delay becoming a parent; whatever the reason, this trend is linked to significant health and economic impacts. Many Canadians are unaware of the impact this may have on their fertility and potential birth outcomes. It is important that health care professionals apprise individuals in their reproductive years about these issues and the steps they can take to mitigate these risks. Implementing a health equity and broader determinants of health approach through social policy development may also prove beneficial. Such upstream approaches could enhance maternal and child health outcomes, and also help ensure that people of reproductive age are making an informed decision about delaying parenthood. This article calls for developing a comprehensive preconception health promotion and care strategy encompassing individual, community and population level approaches.

Selective mutation accumulation: a computational model of the paternal age effect.

MOTIVATION: As the mean age of parenthood grows, the effect of parental age on genetic disease and child health becomes ever more important. A number of autosomal dominant disorders show a dramatic paternal age effect due to selfish mutations: substitutions that grant spermatogonial stem cells (SSCs) a selective advantage in the testes of the father, but have a deleterious effect in offspring. In this paper we present a computational technique to model the SSC niche in order to examine the phenomenon and draw conclusions across different genes and disorders. RESULTS: We used a Markov chain to model the probabilities of mutation and positive selection with cell divisions. The model was fitted to available data on disease incidence and also mutation assays of sperm donors. Strength of selective advantage is presented for a range of disorders including Apert's syndrome and achondroplasia. Incidence of the diseases was predicted closely for most disorders and was heavily influenced by the site-specific mutation rate and the number of mutable alleles. The model also successfully predicted a stronger selective advantage for more strongly activating gain-of-function mutations within the same gene. Both positive selection and the rate of copy-error mutations are important in adequately explaining the paternal age effect. AVAILABILITY AND IMPLEMENTATION: C ++/R source codes and documentation including compilation instructions are available under GNU license at https://github.com/anwala/NicheSimulation CONTACT: ewhel001@odu.eduSupplementary information: Supplementary data are available at Bioinformatics online.

Son Preference, Fertility Decline, and the Nonmissing Girls of Turkey.

Couples in Turkey exhibit son preference through son-biased differential stopping behavior that does not cause a sex ratio imbalance in the population. Demand for sons leads to lower ratios of boys to girls in larger families but higher ratios in smaller families. Girls are born earlier than their male siblings, and son-biased fertility behavior is persistent in response to decline in fertility over time and across households with parents from different backgrounds. Parents use contraceptive methods to halt fertility following a male birth. The sibling sex composition is associated with gender disparities in health. Among third- or later-born children, female infant mortality is 1.5 percentage points lower if the previous sibling is male. The female survival advantage, however, disappears if the previous sibling is female. Having an older female sibling shifts the gender gap in infant mortality rate by 2 percentage points in favor of males. The improvement in infant mortality is strongest in favor of males who have no older male siblings.

Risk assessment of medically assisted reproduction and advanced maternal ages in the development of Prader-Willi syndrome due to UPD(15)mat.

Recent studies have suggested that disomic oocyte-mediated uniparental disomy 15 (UPD(15)mat) is increased in patients with Prader-Willi syndrome (PWS) born after medically assisted reproduction (MAR). However, it remains unknown whether the increase is primarily due to MAR procedure itself or advanced maternal childbearing ages as a predisposing factor for the disomic oocyte production. To examine this matter, we studied 122 naturally conceived PWS patients (PWS-NC group) and 13 MAR-conceived patients (PWS-MAR group). The relative frequency of disomic oocyte-mediated UPD(15)mat was significantly higher in PWS-MAR group than in PWS-NC group (7/13 vs 20/122, p = 0.0045), and the maternal childbearing ages were significantly higher in PWS-MAR group than in PWS-NC group [median (range), 38 (26-45) vs 30 (19-42), p = 0.0015]. However, the logistic regression analysis revealed no significant association between the occurrence of disomic oocyte-mediated UPD(15)mat and MAR, after adjusting for childbearing age (p = 0.25). Consistent with this, while the frequency of assisted reproductive technology (ART)-conceived livebirths was higher in the PWS patients than in the Japanese general population (6.4% vs 1.1%, p = 0.00018), the distribution of childbearing ages was significantly skewed to the increased ages in the PWS patients (p < 2.2 × 10(-16) ). These results argue against a positive association of MAR procedure itself with the development of UPD(15)mat.

Aging fatherhood in Finland - first-time fathers in Finland from 1987 to 2009.

AIM: The increase in maternal age has been well documented in Western societies, but information on paternal age trends is scarce. The aim of this study was to investigate changes in age and other background characteristics of first-time fathers in Finland in the period 1987-2009. MATERIALS AND METHODS: A random 60% sample of first-time fathers in each year from 1987 to 2009 was obtained from Statistics Finland (n=344,529). Five-year intervals were used (three years in 1987-1989). Sociodemographic characteristics of older first-time fathers (⩾40 years) were compared over time using logistic regression. In the logistic regression, immigrants were excluded from the study population as they may have had children before migrating to Finland. RESULTS: The mean age of first-time fathers increased from 28.7 to 30.4 years in 1987-2009. The change was greatest in the Capital Region and smallest in Northern and Eastern Finland. Fatherhood at the age of ⩾40 years doubled from 3.1% to 6.8%. From 2005 to 2009, men who lived in rural areas and the Capital Region, had a long education, were divorced or widowed, had been born in a rural area and were native Finnish speakers, were more likely than other men to be old when they became fathers. CONCLUSIONS DURING THE STUDY PERIOD, THE AVERAGE AGE OF FIRST-TIME FATHERS INCREASED BY TWO YEARS FURTHER STUDIES ARE NEEDED TO EXAMINE WHETHER DELAYS IN FIRST-TIME FATHERHOOD AFFECT FERTILITY, CHILD HEALTH AND THE USE OF SOCIAL AND HEALTH SERVICES.

Immigration policy and birth weight: Positive externalities in Italian law.

A decade ago, the political party of the Italian center-right voted a law restricting immigration. The law became effective in early 2005, when the Italian parliament approved the decree for its application, but one of its articles, granting amnesty for illegal immigrant workers, became immediately effective in July 2002. As a result, 650,000 immigrants were granted the status of foreign nationals in Italy. In this paper, we examine whether the increase in the prevalence of "regular immigrants" has led to an improvement in health outcomes of babies born to migrant women, measured in terms of birth weight. Two hitherto unexploited birth sample surveys published by Italian Institute of Statistics were used for this study. Our estimates show that regularized immigration reduced the probability of low birth weight.

Intergenerational transmission of parenting: findings from a UK longitudinal study.

BACKGROUND: The quality of parenting is associated with a wide range of child and adult outcomes, and there is evidence to suggest that some aspects of parenting show patterns of intergenerational transmission. This study aimed to determine whether such intergenerational transmission occurs in mothers and fathers in a UK birth cohort. METHODS: The study sample consisted of 146 mothers and 146 fathers who were recruited from maternity wards in England and followed up for 24 months ['Generation 2' (G2)]. Perceptions of their own parenting [by 'Generation1' (G1)] were assessed from G2 parents at 12 months using the Parental Bonding Instrument (PBI). G2 parents were filmed interacting with their 'Generation 3' (G3) children at 24 months. RESULTS: We found that G1 mothers' 'affection' was associated with positive parenting behaviour in the G2 fathers ('positive responsiveness' ß = 0.19, P = 0.04 and 'cognitive stimulation' ß = 0.26, P < 0.01). G1 mothers' 'control' was associated with negative parenting behaviour in G2 mothers (decreased 'engagement' ß = -0.19, P = 0.04), and negative parenting behaviour in G2 fathers (increased 'control' ß = 0.18, P = 0.05). None of the G1 fathers' parenting variables were significantly associated with G2 parenting. CONCLUSIONS: There is evidence of intergenerational transmission of parenting behaviour in this highly educated UK cohort, with reported parenting of grandmothers associated with observed parenting in both mothers and fathers. No association was seen with reported parenting of grandfathers. This raises the possibility that parenting interventions may have benefits that are realised across generations.

Reactivity and sleep in infants: a longitudinal objective assessment.

Sleep patterns and temperament in the first year of life are closely related. However, research utilizing objective, rather than subjective measurements of sleep and temperament is scarce and results are inconsistent. In addition, a relative lack of longitudinal data prevents inference of causality between the two constructs. In this study, infant sleep was objectively assessed among 95 infants at 3, 6, and 12 months-of-age with an actigraph in the home setting. Reactivity to sound, light, and touch, a specific aspect of temperament, was behaviorally assessed at 3 and 6 months, both during sleep (at home) and during waking (at the laboratory). Expected maturational trends were recorded in sleep, with a temporal increase in sleep efficiency and percent of motionless sleep. Quadratic (i.e., inverse U shape) relations were found, especially among girls, when predicting change in sleep by reactivity thresholds, suggesting that both hyposensitive and hypersensitive infants are at risk for poor sleep quality. These are the first research findings suggesting that low reactivity in infancy might be associated with compromised sleep quality. The observed nonlinear effects may account for null or inconsistent results in previous studies that explored only linear associations between temperament and sleep. Future studies should address both extremes of the temperament continuum when exploring relations with sleep patterns.

Paternal age predicts offspring chances of marriage and reproduction.

OBJECTIVES: Mutation-selection balance theory proposes that a balance of forces between constantly arising mildly harmful mutations and selection causes variation in genetic configuration and phenotypic condition. As mutations are predominantly deleterious, the entry of variation due to mutations is kept at low frequencies by selection. It has recently been demonstrated that nearly all de novo mutation are caused by paternal age. METHODS: We examined on basis of the Wisconsin Longitudinal Study (n = 6,182) whether a subject's probability of having ever married as well as having ever reproduced is associated with that subject's father's age at subject's birth. RESULTS: We find that advanced paternal but not maternal age at subject's birth predicts a lower chance of ever being married and a higher chance of childlessness, even controlling for various confounders. CONCLUSIONS: As marriage is a prerequisite of reproduction in this sample, we discuss that mate choice may provide a mechanism to prevent too high mutation load in the progeny.