Fertility

About: Fertility is a research topic. Over the lifetime, 29988 publications have been published within this topic receiving 681106 citations.

The Effect of Welfare on Marriage and Fertility

Abstract: The recent literature on the effects of welfare on marriage and fertility includes studies employing a wide variety of methodologies and data sets and covering different time periods. A majority of the studies show that welfare has a significantly negative effect on marriage or positive effect on fertility rather than none at all, and thus the current consensus is that the welfare system probably has some effect on these demographic outcomes. Considerable uncertainty surrounds this consensus because a sizable minority of the studies find no effect at all, because the magnitudes of the estimated effects vary widely, and because puzzling and unexplained differences exist across the studies by race and methodological approach. At present, and with the information provided in the studies, the source of these disparities cannot be determined. While a neutral weighing of the evidence still leads to the conclusion that the welfare system affects marriage and fertility, research needs to be conducted to resolve the conflicting findings. The Effect of Welfare on Marriage and Fertility: What Do We Know and What Do We Need to Know? The research literature over the last 30 years on the effects of welfare on marriage and fertility includes studies employing a variety of methodologies and data sets and covering different time periods. Several studies were conducted in the 1970s and early 1980s, but a second wave of studies began in the mid-1980s and is still under way. Based on the early work, a consensus among researchers developed a decade or so ago that the welfare system had no effect on marriage and fertility. However, a majority of the newer studies show that welfare has a significantly negative effect on marriage or positive effect on fertility rather than none at all. Because of this shift in findings, the current consensus is that the welfare system probably has some effect on these demographic outcomes. However, considerable uncertainty surrounds this consensus because a significant minority of the studies find no effect at all, because the magnitudes of the estimated effects vary widely, and because puzzling and unexplained differences exist across the studies by race and methodological approach. For example, the findings show considerably stronger effects for white women than for black or nonwhite women, despite the greater participation rates of the latter group in the welfare system. Also, the findings often differ when demographic outcomes are correlated with welfare generosity in different ways—variation in welfare benefits across states in a particular year, for example, versus variation in welfare benefits over time. Whether the differences in study findings result from inherent differences in different data sets or from differences in the way the data are analyzed—for example, in estimating techniques, definitions of variables, characteristics of the individuals examined, and other influences controlled for—is difficult to determine because most authors do not systematically attempt to determine why their findings differ from those of other studies. This paper summarizes the relevant literature and discusses the differences across studies. Because of the diversity of findings, methodological considerations necessarily must be a major focus of the discussion. Section I provides background on the U.S. welfare system and those aspects of its 2 structure relevant to marriage and fertility and discusses the context of social science theories of marriage and fertility in which the welfare system plays a role. Section II outlines the different questions of interest and discusses those questions that have been addressed in the research literature. Section III discusses the methodological approach taken in the research literature toward the question and contrasts the method of experimentation with the nonexperimental method of using natural program variation. Broad trends in the U.S. on demographic outcomes and the welfare system are presented in Section IV; these trends establish a set of basic patterns in the data. Section V reviews the multivariate research studies on the question, compares and contrasts their approaches, and discusses possible reasons for the diversity of findings. Finally, suggestions for future research are outlined in Section VI.

Effects of increased paternal age on sperm quality, reproductive outcome and associated epigenetic risks to offspring

Abstract: Over the last decade, there has been a significant increase in average paternal age when the first child is conceived, either due to increased life expectancy, widespread use of contraception, late marriages and other factors. While the effect of maternal ageing on fertilization and reproduction is well known and several studies have shown that women over 35 years have a higher risk of infertility, pregnancy complications, spontaneous abortion, congenital anomalies, and perinatal complications. The effect of paternal age on semen quality and reproductive function is controversial for several reasons. First, there is no universal definition for advanced paternal ageing. Secondly, the literature is full of studies with conflicting results, especially for the most common parameters tested. Advancing paternal age also has been associated with increased risk of genetic disease. Our exhaustive literature review has demonstrated negative effects on sperm quality and testicular functions with increasing paternal age. Epigenetics changes, DNA mutations along with chromosomal aneuploidies have been associated with increasing paternal age. In addition to increased risk of male infertility, paternal age has also been demonstrated to impact reproductive and fertility outcomes including a decrease in IVF/ICSI success rate and increasing rate of preterm birth. Increasing paternal age has shown to increase the incidence of different types of disorders like autism, schizophrenia, bipolar disorders, and childhood leukemia in the progeny. It is thereby essential to educate the infertile couples on the disturbing links between increased paternal age and rising disorders in their offspring, to better counsel them during their reproductive years.

The old-age security motive for fertility.

Abstract: The conditions under which the old-age security motive could be expected to be significant for fertility are described. Such conditions are likely to prevail in rural areas of developing countries and especially among women. Empirical studies on the subject are evaluated and the inconclusive and contradictory nature of the findings are attributed to failures to select appropriate samples and variables. Most findings derive from studies only marginally concerned with the old-age security motive for fertility. The paper concludes with suggestions for future research. Some of the earlier studies found surprisingly little or no relation between the old-age pension participation variables and various measures of fertility especially in developing countries. More recent studies have generally found significant negative relationships. Entwisle and Winegarden obtained evidence of a reinforcing feedback from low fertility to the expansion of the depth and breadth of coverage of participation in old-age security programs. A study done by DeVany and Sanchez concluded that the land-retention and other benefits of children to their parents are greater for those living on land which cannot be bought or sold than for those on privately owned land. Nugent and Gillaspy found that fertility changes between 1960 and 1970 across counties were negatively related to the size of the social security proxy variable. Cains 1981 study showed that the insecurity characterizing rural areas of developing countries is not limited to old age and disability but also includes calamitous events whose presence contribute to high fertility. The 1980 study of Vlassoff and Vlassoff concluded that old-age security was unimportant as a motive for fertility. There is a need for additional more systematic and more special-purpose empirical studies to investigate the impact of old-age security on fertility. Studies should be conducted in rural areas of developing countries where the old-age pension motive is expected to be strong. The sample size should be large enough to afford the opportunity to isolate the old-age pension affects from the effects of other variables and data collection should be repeated at various times. (summaries in ENG FRE SPA)

A European perspective on testicular tissue cryopreservation for fertility preservation in prepubertal and adolescent boys

Abstract: STUDY QUESTION What clinical practices, patient management strategies and experimental methods are currently being used to preserve and restore the fertility of prepubertal boys and adolescent males? SUMMARY ANSWER Based on a review of the clinical literature and research evidence for sperm freezing and testicular tissue cryopreservation, and after consideration of the relevant ethical and legal challenges, an algorithm for the cryopreservation of sperm and testicular tissue is proposed for prepubertal boys and adolescent males at high risk of fertility loss. WHAT IS KNOWN ALREADY A known late effect of the chemotherapy agents and radiation exposure regimes used to treat childhood cancers and other non-malignant conditions in males is the damage and/or loss of the proliferating spermatogonial stem cells in the testis. Cryopreservation of spermatozoa is the first line treatment for fertility preservation in adolescent males. Where sperm retrieval is impossible, such as in prepubertal boys, or it is unfeasible in adolescents prior to the onset of ablative therapies, alternative experimental treatments such as testicular tissue cryopreservation and the harvesting and banking of isolated spermatogonial stem cells can now be proposed as viable means of preserving fertility. STUDY DESIGN, SIZE, DURATION Advances in clinical treatments, patient management strategies and the research methods used to preserve sperm and testicular tissue for prepubertal boys and adolescents were reviewed. A snapshot of the up-take of testis cryopreservation as a means to preserve the fertility of young males prior to December 2012 was provided using a questionnaire. PARTICIPANTS/MATERIALS, SETTING, METHODS A comprehensive literature review was conducted. In addition, survey results of testis freezing practices in young patients were collated from 24 European centres and Israeli University Hospitals. MAIN RESULTS AND THE ROLE OF CHANCE There is increasing evidence of the use of testicular tissue cryopreservation as a means to preserve the fertility of pre- and peri-pubertal boys of up to 16 year-old. The survey results indicate that of the 14 respondents, half of the centres were actively offering testis tissue cryobanking as a means of safeguarding the future fertility of boys and adolescents as more than 260 young patients (age range less than 1 year old to 16 years of age), had already undergone testicular tissue retrieval and storage for fertility preservation. The remaining centres were considering the implementation of a tissue-based fertility preservation programme for boys undergoing oncological treatments. LIMITATIONS, REASONS FOR CAUTION The data collected were limited by the scope of the questionnaire, the geographical range of the survey area, and the small number of respondents. WIDER IMPLICATIONS OF THE FINDINGS The clinical and research questions identified and the ethical and legal issues raised are highly relevant to the multi-disciplinary teams developing treatment strategies to preserve the fertility of prepubertal and adolescent boys who have a high risk of fertility loss due to ablative interventions, trauma or genetic pre-disposition. STUDY FUNDING/COMPETING INTEREST(S) The work was funded by the European Society of Human Reproduction and Embryology (ESHRE).

Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies

Abstract: Background Infertility is a global public health issue, affecting 15% of all couples of reproductive age. Male factors, including decreased semen quality, are responsible for ~25% of these cases. The dietary pattern, the components of the diet and nutrients have been studied as possible determinants of sperm function and/or fertility. Objective and rationale Previous systematic reviews have been made of the few heterogeneous low-quality randomized clinical trials (RCTs) conducted in small samples of participants and investigating the effect of specific nutrients and nutritional supplements on male infertility. However, as yet there has been no systematic review of observational studies. Search methods A comprehensive systematic review was made of the published literature, from the earliest available online indexing year to November 2016, in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We have included cross-sectional, case-control and prospective and retrospective studies in which fertile/infertile men were well defined (men with sperm disorders, sperm DNA damage, varicocele or idiopathic infertility). The primary outcomes were semen quality or fecundability. With the data extracted, we evaluated and scored the quality of the studies selected. We excluded RCTs, animal studies, review articles and low-quality studies. Outcomes A total of 1944 articles were identified, of which 35 were selected for qualitative analysis. Generally, the results indicated that healthy diets rich in some nutrients such as omega-3 fatty acids, some antioxidants (vitamin E, vitamin C, β-carotene, selenium, zinc, cryptoxanthin and lycopene), other vitamins (vitamin D and folate) and low in saturated fatty acids and trans-fatty acids were inversely associated with low semen quality parameters. Fish, shellfish and seafood, poultry, cereals, vegetables and fruits, low-fat dairy and skimmed milk were positively associated with several sperm quality parameters. However, diets rich in processed meat, soy foods, potatoes, full-fat dairy and total dairy products, cheese, coffee, alcohol, sugar-sweetened beverages and sweets have been detrimentally associated with the quality of semen in some studies. As far as fecundability is concerned, a high intake of alcohol, caffeine and red meat and processed meat by males has a negative influence on the chance of pregnancy or fertilization rates in their partners. Wider implications Male adherence to a healthy diet could improve semen quality and fecundability rates. Since observational studies may prove associations but not causation, the associations summarized in the present review need to be confirmed with large prospective cohort studies and especially with well-designed RCTs.