Paternal preconception modifiable risk factors for adverse pregnancy and offspring outcomes: a review of contemporary evidence from observational studies

Transgenerational effects of paternal exposures: the role of germline de novo mutations

Germline de novo mutations (DNMs) refer to spontaneous mutations arising during gametogenesis, resulting in genetic changes within germ cells that are subsequently transmitted to the next generation. While the impact of maternal exposures on germline DNMs has been extensively studied, more recent studies have begun to highlight the increasing importance of the effects of paternal factors. In this review, we have summarized the existing literature on how various exposures experienced by fathers affect the germline DNM burden in their spermatozoa, as well as their consequences for semen analysis parameters, pregnancy outcomes, and offspring health. A growing body of literature supports the conclusion that advanced paternal age (APA) correlates with a higher germline DNM rate in offspring. Furthermore, lifestyle choices, environmental toxins, assisted reproductive techniques (ART), and chemotherapy are associated with the accumulation of paternal DNMs in spermatozoa, with deleterious consequences for pregnancy outcomes and offspring health. Ultimately, our review highlights the clear importance of the germline DNM mode of inheritance, and the current understanding of how this is affected by various paternal factors. In addition, we explore conflicting reports or gaps of knowledge that should be addressed in future research.

Preconception health in adolescence and adulthood across generations in the UK: Findings from three British birth cohort studies

Optimising preconception health in women and men holds significant potential for improving pregnancy and offspring health outcomes. To create a picture of the state of preconception health in the UK, this study aimed to describe the prevalence of and changes in preconception health indicators reported in three British birth cohort studies: the 1970 British Birth Cohort Study (BCS70; born in 1970; N = 17,198), Next Steps (1989-1990; N = 15,770), and Millennium Cohort Study (MCS; 2000-2002; N = 19,517). The analysis focused on data obtained during participants' adolescence (16-17 years) and subsequent follow-ups at 25-26 years for BCS70 and Next Steps. Self-reported preconception indicators were defined in line with a previously published review and reported as proportions. Across cohorts, data were available for 14 preconception indicators across four domains: health behaviours and weight, reproductive health and family planning, physical health conditions, and wider determinants of health. However, data for these indicators were not consistently available for all cohort members. Findings suggested persistent suboptimal health behaviours in both genders and across generations, including low intakes of fruit. While alcohol, tobacco, and soft drink intake decreased across generations, obesity prevalence surged. This study underscores the need for public health interventions targeting the root causes of adverse health behaviours towards improvement of fruit consumption, further reduction in alcohol, tobacco, and soft drink consumption, and addressing the escalating obesity rates among individuals of reproductive age. Ongoing monitoring is needed to continue tracking these existing indicators over time, while improved data quality and availability of a wider range of preconception indicators are crucial to comprehensively understanding the complexities of preconception health, enabling the development of more targeted and effective interventions.

Paternal age, de novo mutations, and offspring health? New directions for an ageing problem

This Directions article examines the mechanisms by which a father's age impacts the health and wellbeing of his children. Such impacts are significant and include adverse birth outcomes, dominant genetic conditions, neuropsychiatric disorders, and a variety of congenital developmental defects. As well as age, a wide variety of environmental and lifestyle factors are also known to impact offspring health via changes mediated by the male germ line. This picture of a dynamic germ line responsive to a wide range of intrinsic and extrinsic factors contrasts with the results of trio studies indicating that the incidence of mutations in the male germ line is low and exhibits a linear, monotonic increase with paternal age (∼two new mutations per year). While the traditional explanation for this pattern of mutation has been the metronomic plod of replication errors, an alternative model pivots around the 'faulty male' hypothesis. According to this concept, the genetic integrity of the male germ line can be dynamically impacted by age and a variety of other factors, and it is the aberrant repair of such damage that drives mutagenesis. Fortunately, DNA proofreading during spermatogenesis is extremely effective and these mutant cells are either repaired or deleted by apoptosis/ferroptosis. There appear to be only two mechanisms by which mutant germ cells can escape this apoptotic fate: (i) if the germ cells acquire a mutation that by enhancing proliferation or suppressing apoptosis, permits their clonal expansion (selfish selection hypothesis) or (ii) if a genetically damaged spermatozoon manages to fertilize an oocyte, which then fixes the damage as a mutation (or epimutation) as a result of defective DNA repair (oocyte collusion hypothesis). Exploration of these proposed mechanisms should not only help us better understand the aetiology of paternal age effects but also inform potential avenues of remediation.

Developing consensus on priorities for preconception care in the general practice setting in the UK: Study protocol

BACKGROUND

Preconception medical, behavioural and socioeconomic risk factors are common among people of reproductive age and can impact pregnancy and offspring outcomes. In line with clinical guidance, primary care practitioners are encouraged to support patients to manage and optimise their health prior to pregnancy. Due to barriers, including lack of time and resources, this support is not currently part of routine practice.

AIM

As a first step towards the co-development of practical and realistic best practice guidance, this study aims to achieve consensus on a list of priority risk factors that can be used in general practice to guide opportunistic preconception care for patients of reproductive age.

METHODS

This study protocol was developed with a Public Advisory Group of people of reproductive age, researchers and primary care practitioners. The consensus study will consist of three steps: 1) identifying an initial long-list of candidate risk factors and defining principles for scoring the importance of each risk factor, through a literature review, workshops with people of reproductive age, and interviews with primary care practitioners; 2) stakeholder participant prioritisation of each candidate risk factor for its importance for preconception care through a three-round eDelphi survey; and 3) agreeing on the final priority list through consensus meetings with a selected group of stakeholders. Participants living in the UK will be recruited across two stakeholder groups: people of reproductive age (through the Public Advisory Group and charities) and primary care professionals (through professional organisations).

ETHICAL APPROVAL

This study has been approved by the University of Southampton Faculty of Medicine Ethics Committee (ERGO 83699 and 92950).

DISSEMINATION

All study findings will be shared through stakeholder participants, peer-reviewed publication, lay summary, meetings and conference presentations, and relevant professional and community organisations. Ongoing research will inform implementation of the priority list in clinical practice.

What Does 'Preconception Health' Mean to People? A Public Consultation on Awareness and Use of Language

INTRODUCTION

There is growing scientific and policy recognition that optimising health before a potential pregnancy (preconception health) improves reproductive outcomes and the lifelong health of future children. However, public awareness on this topic is low. We conducted a public consultation to develop language recommendations and identify and prioritise approaches to inform research and improve public awareness of preconception health.

METHODS

A public consultation was undertaken with people of any gender aged 18-50 years living in the United Kingdom who were not currently expecting a child. Public contributors were recruited through patient and public involvement, community and support groups, an existing cohort study, and an LGBTQ+ charity. An initial round of online group discussions (February/March 2021) explored public contributors' knowledge of preconception health, their recommendations for appropriate language, and ideas about public health approaches. In a subsequent discussion round (May 2021), language recommendations were refined and suggested approaches prioritised. Discussions were summarised based on notes taken by two researchers.

RESULTS

Fifty-four people joined the initial discussion round (66% women, 21% men, 13% nonbinary or transgender; 55% aged 18-30 years, 30% 31-40 years, 15% 41-50 years). Of these, 36 people (67%) participated in the subsequent round. Very few had heard the term 'preconception health', understood what it means, or why and for whom it is important. They recommended avoiding unfamiliar terms without further explanation (e.g., preconception health, medical terms), using language that is positive, encouraging and gender-sensitive where possible, and using messages that are specific, nonjudgmental and realistic. The phrases 'health and well-being during the childbearing years', 'health and well-being before pregnancy and parenthood' and 'planning for parenthood' resonated with most public contributors. School-based education, social media campaigns and the National Health Service emerged as priority approaches/settings for raising awareness.

CONCLUSION

This public consultation produced recommendations from a diverse group of people of reproductive age in the United Kingdom to improve language and prioritise approaches that increase public understanding of preconception health in ways that are relevant and appropriate to them. This should begin in schools and will require adaptation of curricula, alongside co-development of public awareness campaigns and guidance for healthcare professionals.

PATIENT OR PUBLIC CONTRIBUTION

This public consultation included a diverse group of members of the public. They were not involved in the original design of the project, but following the initial round of online group discussions, they contributed to the interpretation and refinement of the emerging concepts in a subsequent round of group meetings. After the consultation activity, public contributors formed a Public Advisory Group and have subsequently been involved in other studies on the same topic. Two public contributors (E.R. and F.F.) provided critical input in the preparation and revision of this manuscript and are co-authors of the paper.

Neurological Disorders Induced by Drug Use: Effects of Adolescent and Embryonic Drug Exposure on Behavioral Neurodevelopment

Clinical studies demonstrate that the risk of developing neurological disorders is increased by overconsumption of the commonly used drugs, alcohol, nicotine and cannabis. These drug-induced neurological disorders, which include substance use disorder (SUD) and its co-occurring emotional conditions such as anxiety and depression, are observed not only in adults but also with drug use during adolescence and after prenatal exposure to these drugs, and they are accompanied by long-lasting disturbances in brain development. This report provides overviews of clinical and preclinical studies, which confirm these adverse effects in adolescents and the offspring prenatally exposed to the drugs and include a more in-depth description of specific neuronal systems, their neurocircuitry and molecular mechanisms, affected by drug exposure and of specific techniques used to determine if these effects in the brain are causally related to the behavioral disturbances. With analysis of further studies, this review then addresses four specific questions that are important for fully understanding the impact that drug use in young individuals can have on future pregnancies and their offspring. Evidence demonstrates that the adverse effects on their brain and behavior can occur: (1) at low doses with short periods of drug exposure during pregnancy; (2) after pre-conception drug use by both females and males; (3) in subsequent generations following the initial drug exposure; and (4) in a sex-dependent manner, with drug use producing a greater risk in females than males of developing SUDs with emotional conditions and female offspring after prenatal drug exposure responding more adversely than male offspring. With the recent rise in drug use by adolescents and pregnant women that has occurred in association with the legalization of cannabis and increased availability of vaping tools, these conclusions from the clinical and preclinical literature are particularly alarming and underscore the urgent need to educate young women and men about the possible harmful effects of early drug use and to seek novel therapeutic strategies that might help to limit drug use in young individuals.

Influence of paternal preconception health on pregnancy, intrapartum, postpartum and early childhood outcomes: protocol for a parallel scoping review

INTRODUCTION

Preconception care is the provision of behavioural, social or biomedical interventions to women and couples prior to conception. To date, preconception research has primarily focused on maternal health, despite the male partner's contribution before birth to both short-term and long-term child outcomes. The objectives of the reviews are: (1) to identify, consolidate and analyse the literature on paternal preconception health on pregnancy and intrapartum outcomes, and (2) to identify, consolidate and analyse the literature on paternal preconception health on postpartum and early childhood outcomes.

METHODS AND ANALYSIS

A scoping review will be conducted following the Joanna Briggs Institute methodology. MEDLINE, PsycINFO, Embase, Scopus and CINAHL databases will be searched for articles published in English. Two independent reviewers will screen titles and abstracts and then full text using Covidence, with conflicts resolved by a third reviewer. Data extraction will be performed using Covidence.

ETHICS AND DISSEMINATION

Ethics approval is not required for this scoping review. Results will be published in peer-reviewed journals as well as presented at relevant national and international conferences and meetings.

Preconception Health of Indigenous Peoples in Australia, Canada, New Zealand, and the United States: A Scoping Review

BACKGROUND

There is increasing recognition of the importance of the preconception period for addressing reproductive and intergenerational health inequities and supporting improved maternal and child health outcomes. This study aimed to understand the extent and type of evidence that exists in relation to preconception health for Indigenous peoples living in high-income countries with similar experiences of colonisation, namely, Australia, New Zealand, Canada, and the United States.

METHODS

This review was conducted as per the JBI methodology and PRISMA Extension for Scoping Reviews. A comprehensive search of PubMed, CINAHL [EBSCO], Ovid Embase, Scopus, and the Wiley Cochrane Library was conducted using keywords and index terms. We included research in English published between January 2010 and June 2023 on quantitative and qualitative primary studies. Data were extracted using a standardised tool, and the analysis included quantitative descriptions and qualitative content analysis.

RESULTS

We identified 360 potential studies and included 57 articles in the review. Most studies were from the United States (n = 36, 63.2%) and Australia (n = 13, 22.8%), and they commonly reported associations between preconception health risk factors and maternal or child health outcomes (n = 27, 48.2%) or described the development, implementation, or evaluation of preconception health interventions (n = 26, 46.4%). Common preconception health areas were pre-pregnancy body mass index or weight (n = 34), alcohol (n = 16), diet (n = 14), physical activity (n = 12), and diabetes (n = 11). Most studies focused exclusively on women (n = 46, 80.7%), and very few included men (n = 3, 5.3%). The study populations were mostly urban and rural (n = 25, 43.9%) or rural only (n = 14, 24.6%); however, the geographical remoteness was often unclear (n = 14, 24.6%).

CONCLUSIONS

While there was some research relating to the preconception health of Indigenous peoples, this review identified considerable research gaps. There is a need for dedicated research into preconception health risk factors and reproductive health outcomes, attitudes and awareness of preconception health, and preconception health interventions for Indigenous peoples.

Maternal pre-pregnancy BMI and reproductive health in adult sons: a study in the Danish National Birth Cohort

STUDY QUESTION

Is maternal pre-pregnancy BMI associated with semen quality, testes volume, and reproductive hormone levels in sons?

SUMMARY ANSWER

Maternal pre-pregnancy BMI was associated with an altered reproductive hormone profile in young adult sons, characterized by higher levels of oestradiol, LH, and free androgen index (FAI) and lower levels of sex hormone-binding globulin (SHBG) in sons born of mothers with pre-pregnancy overweight and obesity.

WHAT IS KNOWN ALREADY

Evidence suggests that maternal pre-pregnancy BMI may influence reproductive health later in life. Only one pilot study has investigated the association between maternal pre-pregnancy BMI and reproductive health outcomes in sons, suggesting that a high BMI was associated with impaired reproductive function in the adult sons.

STUDY DESIGN, SIZE, DURATION

A population-based follow-up study of 1058 young men from the Fetal Programming of Semen Quality (FEPOS) cohort nested within the Danish National Birth Cohort (DNBC), 1998-2019, was carried out.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 1058 adult sons (median age 19 years, 2 months), born 1998-2000 by mothers included in the DNBC, participated in FEPOS. At a clinical examination, they provided a semen and blood sample, measured their testes volume, and had height and weight measured. Maternal pre-pregnancy BMI was obtained by self-report in early pregnancy. Semen characteristics, testes volume, and reproductive hormone levels were analysed according to maternal pre-pregnancy BMI categories and as restricted cubic splines using negative binomial and ordinary least square regression models. Mediation analyses examined potential mediation by the sons' birthweight, pubertal timing, fat mass, and BMI. Additional analyses investigated the role of paternal BMI in the potential associations between maternal BMI and reproductive health outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

We found no consistent associations between maternal pre-pregnancy BMI and semen characteristics or testes volume. Sons of mothers with higher pre-pregnancy BMI had higher oestradiol and lower SHBG levels, both in a dose-dependent manner. Sons of mothers with pre-pregnancy obesity (≥30 kg/m2) had higher LH levels and a higher FAI than sons born by mothers with normal pre-pregnancy BMI (18.5-24.9 kg/m2). The mediation analyses suggested that the effect of maternal pre-pregnancy BMI on higher levels of oestrogen, LH, and FAI was partly mediated by the sons' birthweight, in addition to adult fat mass and BMI measured at the clinical examination, whereas most of the effect on lower levels of SHBG was primarily mediated by the sons' own fat mass and BMI. Paternal BMI was not a strong confounder of the associations in this study.

LIMITATIONS, REASONS FOR CAUTION

This study was based in a population-based cohort with a low prevalence of overweight and obesity in both mothers and adult sons. Some men (10%) had blood for reproductive hormone assessment drawn in the evening. While several potential confounding factors were accounted for, this study's inherent risk of residual and unmeasured confounding precludes provision of causal estimates. Therefore, caution should be given when interpreting the causal effect of maternal BMI on sons' reproductive health.

WIDER IMPLICATIONS OF THE FINDINGS

Given the widespread occurrence of overweight and obesity among pregnant women, it is imperative to thoroughly examine the potential consequences for reproductive hormone levels in adult sons. The potential effects of maternal pre-pregnancy obesity on sons' reproductive hormone profile may potentially be partly avoided by the prevention of overweight and obesity in the sons.

STUDY FUNDING/COMPETING INTEREST(S)

The project was 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), AP Møller Foundation (16-37), the Health Foundation, Dagmar Marshall's Fond, Aarhus University, Independent Research Fund Denmark (9039-00128B), and the European Union (ERC, BIOSFER, 101071773). Views and opinions expressed are, however, those of the authors only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible. The authors declare that they have no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Exploring Health Behaviours, Attitudes and Beliefs of Women and Men during the Preconception and Interconception Periods: A Cross-Sectional Study of Adults on the Island of Ireland

Preconception health is increasingly seen as a key target for improving population health in the UK and Ireland, yet little is known about the attitudes and beliefs of adults regarding preconception care strategies. This online cross-sectional survey aimed to explore the health behaviours, attitudes and beliefs of adults of reproductive age in regard to preconception health and care. The survey was developed by reviewing the previous literature and engaging with those from the target group. It is one of the first surveys to assess the attitudes and beliefs of adults of reproductive age across the Island of Ireland regarding preconception health and care. Results from 386 individuals with a mean age of 29.9 ± 10.3 years were included. A variety of health behaviours, attitudes and beliefs were investigated, with differences being identified between women and men and between participants with or without children (i.e., in the preconception or interconception stage). The majority of respondents held beliefs that preconception care was important, but there was greater emphasis on women than men in terms of the need to engage in health-promoting preconception health behaviours. This study highlights the need to improve preconception health awareness in women and men in the preconception and interconception stage. Findings indicate that efforts to improve preparation for pregnancy among adults of childbearing age are needed, to ensure optimal engagement in preconception health behaviours, with efforts being tailored based on sex and parental status.

Preconception Care: A Strategic Intervention for the Prevention of Neonatal and Birth Disorders

Preconception care is a strategic intervention to improve neonatal and birth outcomes by addressing modifiable risk factors and optimizing maternal and fetal health before pregnancy. This review article examines the importance of preconception care and its impact on preventing neonatal and birth disorders. The methodology involved a comprehensive review of peer-reviewed articles, research studies, and authoritative reports. Key components of preconception care, evidence-based interventions, and their effectiveness in reducing specific neonatal and birth disorders are discussed. The review also highlights the challenges and barriers in implementing preconception care, such as lack of awareness, socioeconomic factors, health system limitations, and policy considerations. Strategies for promoting preconception care, including integration into healthcare systems, raising awareness, healthcare professional education, and collaborations are presented. The conclusion emphasizes the significance of preconception care as a strategic intervention and calls for action by healthcare providers, policymakers, and individuals to prioritize preconception care for better neonatal and birth outcomes.