Is human fecundity changing? A discussion of research and data gaps precluding us from having an answer

Abstract

Fecundity, the biologic capacity to reproduce, is essential for the health of individuals and is, therefore, fundamental for understanding human health at the population level. Given the absence of a population (bio)marker, fecundity is assessed indirectly by various individual-based (e.g. semen quality, ovulation) or couple-based (e.g. time-to-pregnancy) endpoints. Population monitoring of fecundity is challenging, and often defaults to relying on rates of births (fertility) or adverse outcomes such as genitourinary malformations and reproductive site cancers. In light of reported declines in semen quality and fertility rates in some global regions among other changes, the question as to whether human fecundity is changing needs investigation. We review existing data and novel methodological approaches aimed at answering this question from a transdisciplinary perspective. The existing literature is insufficient for answering this question; we provide an overview of currently available resources and novel methods suitable for delineating temporal patterns in human fecundity in future research.

Female exposure to endocrine disrupting chemicals and fecundity: a review

“…Of particular concern is the potential influence of EDCs on female fecundity, or a woman’s ability to become pregnant, given the rising rates of infertility worldwide [4] and the ubiquitous exposure of reproductive aged women to EDCs [5–7]. Because female fecundity lacks a biomarker, it is assessed by a variety of different endpoints including reproductive hormones, markers of ovulation or ovarian reserve, in vitro fertilization (IVF) outcomes, and time-to-pregnancy (TTP) [8]. This review summarizes the most recent epidemiologic literature from humans on the potential effects of female exposure to EDCs on fecundity.…”

Subfertility: philosophy and methodology of the problem. Part І

“…(1990, 2012), которые уточнили вопросы методологии и терминологии в этой проблеме [4,40]. Ниже представленные показатели репродуктивной функции человека приведены в хорошо известных работах отечественных и зарубежных авторов [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53].…”

“…fertility) характеризуется реальным количеством потомков и скоростью рождения в популяции и рассчитывается как число новорожденных на 1000 особей в год. По своей сути, фертильность -это статистически обоснованное выражение плодовитости или же реализация потенциала плодовитости с учетом влияния внешних и внутренних факторов [50,53].…”

Reactive Oxygen Species and Male Fertility

“…The decline of fertility and the increase of abnormalities in the semen of men that is observed over more than two decades is worrisome. However, we still do not have sufficient information to understand why this is happening [53][54][55]. The exposure environmental toxicants could partly explain this phenomenon, but there is still a significant amount of uncertainty regarding the possible causes of the decrease in sperm quality over the years [53,55].…”

“…However, we still do not have sufficient information to understand why this is happening [53][54][55]. The exposure environmental toxicants could partly explain this phenomenon, but there is still a significant amount of uncertainty regarding the possible causes of the decrease in sperm quality over the years [53,55]. It is an established trend that men are delaying fatherhood due to professional reasons, and scientific data from studies in animals and humans revealed that sperm quality worsens as men age.…”