ContextA large body of evidence documents the role of phytoestrogens in influencing
hormone-dependent states. Infants fed soy formula receive high levels of phytoestrogens,
in the form of soy isoflavones, during a stage of development at which permanent
effects are theoretically possible. However, a paucity of data exists on the
long-term effects of infant soy formulas.ObjectiveTo examine the association between infant exposure to soy formula and
health in young adulthood, with an emphasis on reproductive health.Design, Setting, and ParticipantsRetrospective cohort study conducted from March to August 1999 among
adults aged 20 to 34 years who, as infants, participated during 1965-1978
in controlled feeding studies conducted at the University of Iowa, Iowa City
(248 were fed soy formula and 563 were fed cow milk formula during infancy).Main Outcome MeasuresSelf-reported pubertal maturation, menstrual and reproductive history,
height and usual weight, and current health, compared based on type of formula
exposure during infancy.ResultsNo statistically significant differences were observed between groups
in either women or men for more than 30 outcomes. However, women who had been
fed soy formula reported slightly longer duration of menstrual bleeding (adjusted
mean difference, 0.37 days; 95% confidence interval [CI], 0.06-0.68), with
no difference in severity of menstrual flow. They also reported greater discomfort
with menstruation (unadjusted relative risk for extreme discomfort vs no or
mild pain, 1.77; 95% CI, 1.04-3.00).ConclusionsExposure to soy formula does not appear to lead to different general
health or reproductive outcomes than exposure to cow milk formula. Although
the few positive findings should be explored in future studies, our findings
are reassuring about the safety of infant soy formula.

http://www.medicine.mcgill.ca/epidemiology/hanley/c607/ch07/soy.pdf

Exposure to soy-based formula in infancy and endocrinological and reproductive outcomes in young adulthood

BackgroundMale-factor infertility is a common condition, and etiology is unknown for a high proportion of cases. Abnormal epigenetic programming of the germline is proposed as a possible mechanism compromising spermatogenesis of some men currently diagnosed with idiopathic infertility. During germ cell maturation and gametogenesis, cells of the germ line undergo extensive epigenetic reprogramming. This process involves widespread erasure of somatic-like patterns of DNA methylation followed by establishment of sex-specific patterns by de novo DNA methylation. Incomplete reprogramming of the male germ line could, in theory, result in both altered sperm DNA methylation and compromised spermatogenesis.Methodology/Principal FindingWe determined concentration, motility and morphology of sperm in semen samples collected by male members of couples attending an infertility clinic. Using MethyLight and Illumina assays we measured methylation of DNA isolated from purified sperm from the same samples. Methylation at numerous sequences was elevated in DNA from poor quality sperm.ConclusionsThis is the first report of a broad epigenetic defect associated with abnormal semen parameters. Our results suggest that the underlying mechanism for these epigenetic changes may be improper erasure of DNA methylation during epigenetic reprogramming of the male germ line.

/pdf/widespread-epigenetic-abnormalities-suggest-a-broad-dna-4aysoi8wwr.pdf

Widespread epigenetic abnormalities suggest a broad DNA methylation erasure defect in abnormal human sperm

This study of male reproductive health in the Czech Republic resulted from community concern about potential adverse effects of air pollution. We compared young men (18 years of age) living in Teplice, a highly industrialized district with seasonally elevated levels of air pollution, to those from Prachatice, a rural district with relatively clean air. Surveys were scheduled for either late winter, after the season of higher air pollution, or at the end of summer, when pollution was low. Participation included a physical examination, donation of a semen sample, and completion of a questionnaire on health, personal habits, and exposure to solvents and metals through work or hobby. Analysis of data from 408 volunteers showed that the men from Teplice and Prachatice were similar in physical characteristics, personal habits, and work- or hobby-related exposures. Sixty-six percent (272) of these men donated a single semen sample for routine semen analysis, computer-aided sperm motion analysis, and sperm chromatin structure assay. The mean (median) sperm concentration and sperm count were 61. 2 (44.0) million/mL semen and 113.3 (81.5) million, respectively, and were not associated with district of residence or period of elevated air pollution. However, periods of elevated air pollution in Teplice were significantly associated with decrements in other semen measures including proportionately fewer motile sperm, proportionately fewer sperm with normal morphology or normal head shape, and proportionately more sperm with abnormal chromatin. These results suggest that young men may experience alterations in sperm quality after exposure to periods of elevated air pollution, without changes in sperm numbers.

https://www.jstor.org/stable/info/3434998

Semen quality and reproductive health of young Czech men exposed to seasonal air pollution.

Purpose:To investigate whether the sperm concentration of European men is deteriorating over the past 50 years of time.Materials and Methods:We analysed the data published in English language artic...

Decline in sperm count in European men during the past 50 years.

In this article we discuss trends in the limits to late childbearing, their determinants and potential implications from an empirical long-term perspective. Although the high levels observed in non-contracepting populations have not been reached, fertility in Europe at ages 40+ and 45+ has increased substantially in recent years. This trend received considerable attention, especially in combination with the emergence of new reproductive technologies and often low levels of general fertility. Nevertheless, physiological studies agree on the fact that age limits to childbearing, at least for women, have not shifted to later ages. Our empirical analyses of high-quality long-term data from Sweden document an increase in the absolute and relative number of births at ages 40+ and 45+, together with an increase in first birth occurrence-exposure rates at ages close to 40.

Approaching the Limit: Long‐Term Trends in Late and Very Late Fertility

https://www.fertstert.org/article/S0015-0282(99)00591-9/pdf

Tamar Gottfried

Papers

Evaluation of a large cohort of men presenting for a screening semen analysis