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Current query:Type: Scientific Studies
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While all links worked when entries were posted to the database, different publishers
have different policies about retaining articles and providing access to archived material.
Thus some of the links, particularly older ones, may no longer be functional.
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There is good evidence that uterine fibroids interfere with fertility, but poor guidelines on how to manage them for improved fertility outcomes.
The relationship between uterine fibroids and infertility are inconclusive but multiple observations have shown improved conception rates after surgical treatment. Since uterine fibroids can occur in different layers of the uterus and there is variability in the number and size of lesions, treatment should be personalized to each patient's circumstances. Human Reproduction Update. 21 June 2007. More...
Sexual behavior, if not taken into account properly, can be an important confounder in time to pregnancy studies.
An often used metric in determining fertility/fecundability rates in humans is "time to pregnancy", typically defined as the number of menstrual cycles required to achieve a clinical pregnancy. However, the frequency and timing of sexual intercourse during a given cycle can greatly influence the probability of pregnancy. Well-designed studies investigating the effects of contaminants on time to pregnancy should include sexual behavioral patterns. American Journal of Epidemiology 1 May 2007. More...
Mothers of naturally-occurring multiples are found to be have a shorter time to pregnancy than mothers of singletons.
From data collected from 1955-66, the US Collaborative Perinatal Project found women who became pregnant within the first six months of trying to conceive were nearly two times more likely to have a multiple birth than mothers who took longer than 6 months to conceive., Reasons for the heightened fecundity among mothers of multiples is largely unknown, but monitoring naturally-occurring multiple births could help track trends of reproductive health in the general population. Human Reproduction 1 February 2007. More...
Hormonal markers of testicular function may not accurately reflect sperm quality at the population level.
Sperm parameters measured in young men from two regions of Flanders were found to be significantly different in sperm count, concentration, and morphology. However, while free testosterone levels were different in the two communities, no differences were detected in total testosterone (T), follicle stimulating hormone (FSH), inhibin B, T/luteinizing hormone ratio, and inhibin B/FSH ratio. Clinically recognized hormonal parameters should not be substituted from semen quality analysis in population-based studies. Journal of Andrology. 27 December 2006. More...
Science Byte: A study of Latina women and their children found unexpectedly high variation in vulnerability to organophosphate pesticide impacts.
Some newborns were 26 to 50 times more susceptible than others, and 65 to 130 times more sensitive than some adults. The results indicate current standards may not be sufficiently protective. Pharmacogenetics & Genomics. 5 March 2006. More...
In a large study of US women living on farms, use of pesticides is associated with a later age at menopause.
Women who used pesticides underwent menopause an average of 3 months later compared to women who did not use pesticides. This increased to a 5 month delay when hormonally-active pesticides were used, such as atrazine, DDT, lindane, or mancozeb/maneb. Previous studies have found an earlier age at menopause with pesticide exposure; this may be due to differing endocrine disrupting effects in different types of pesticides or differences in study design. American Journal of Epidemiology 22 February 2006. More...
Science Byte: Estimates of pesticide exposures based on questionnaires correlate only moderately with direct measurements of agricultural pesticides in farmers' urine.
These results indicate that traditional approaches based upon questionnaires are likely to have many misclassifications, weakening the ability of the studies to find patterns, and increasing the likelihood that they will conclude a product is safe when it is not. Epidemiology. 26 December 2005. More...
Over 100 scientists with active research programs studying endocrine disruption from 15 countries have issued a joint, signed statement concluding that scientific uncertainty should not delay precautionary action on reducing the exposures to and the risks from endocrine disrupters.
According to their assessment, current safety standards are ill-equipped to deal with risks caused by endocrine disrupters and that current testing procedures may lead to serious underestimations of risk. Effects in wildlife are well established; People in some countries are experiencing high prevalence of disorders consistent with endocrine disruption effects. Because there are inherent difficulties in establishing causality in humans, precautionary action be taken before epidemiological data provide certainty. 23 June 2005. More...
Canadian scientists review the the difficulties involved in linking exposure to putative hazardous substances in environmental and occupational settings to adverse reproductive outcomes, especially success of IVF procedures.
Although reproductive effects of occupational exposure to hazardous chemicals have been well documented in the literature, the potential effects of chemical contaminants at levels representative of contemporary exposures in the general population are much less certain. Evidence for adverse effects of exposure to environmental contaminants is more conclusive among the lower animals than for humans where considerable controversy remains. In addition to potential reproductive hazards of exposure to environmental contaminants, there is also evidence for adverse reproductive effects of the physical and psychosocial environments. Human Reproduction Update 31 January 2005. More...
Study of US men finds changes in reproductive hormones associated with phthalate exposure.
Increasing concentrations of monobenzyl phthalate (MBzP) were associated with a decrease in FSH and monobutyl phthalate (MBP) exposure was associated with an increase in inhibin B. Although associations were found, they were not in the expected direction and it is unclear whether these associations represent physiologically relevant alterations in these hormones, or whether they represent associations found as a result of conducting multiple comparisons. Human Reproduction 9 December 2004. More...
Pollutant levels in NYC air undermine fetal development.
A study of mothers and babies in two NYC minority communities finds that environmental tobacco smoke (ETS) and polycyclic aromatic hydrocarbons (PAHs) are both associated with reduced birth weight and head circumference. The PAH effect is apparent, however, only in subjects exposed to ETS. 16 July 2004. More...
US federal agencies present a research agenda for occupational exposures and reproductive outcomes.
The agencies recommend research based on: a prioritizion of chemical structure and volume of use; expansion of birth defects surveillance systems; and addition of reproductive biologic markers and semen characteristics to national surveys. They add new studies should assess gene-environment interactions and effects of mixtures of chemicals whenever appropriate. Environmental Health Perspectives 1 April 2003. More...
Whereas it may be impossible to definitively say fertility rates have declined, precise monitoring of future trends can establish any further declines.
Such monitoring is justified on the grounds of the importance of early detection of environmental effects on humans reproduction. Establishing a surveillance system sensitive enough to detect changes in fecundity over time is a challenging and it may be impossible to pick up subtle changes. American Journal of Epidemiology 1 January 2003. More...
A study by the Northern California Childhood Leukemia Study (NCCLS) adds new strength to suspected links between pesticides and childhood leukemia.
Pesticide use in the home had its largest effect on childhood leukemia risk during pregnancy. Pesticide application by professionals not only failed to reduce risk but was associated with a more-than-doubling of risk. More frequent applications led to greater risk, as well. Bottom line: avoid home pesticide use if you want to minimize the risk of childhood leukemia in your family. 17 August 2002. More...
Women exposed to high levels of TCDD after an industrial accident in Seveso, Italy tend to have higher rates of endometriosis.
Women with serum TCDD levels greater than 100 ppt were found to have a doubling of risk for endometriosis. However, these results did not reach statistical significance and study results may have been skewed by misclassification of disease status. Environmental Health Perspectives 15 May 2002. More...
Growing evidence from clinical and epidemiological studies points to a cluster of male reproductive problems beginning before birth.
Genital abnormalities such as testicular cancer, reduced semen quality, and subfertility are increasing in incidence. Together these male reproductive problems may reflect the existence of one common entity, a testicular dysgenesis syndrome (TDS). Experimental and epidemiological studies suggest that TDS is a result of disruption of embryonal programming and gonadal development during fetal life and may be causally linked to endocrine disrupters. Annals of the New York Academy of Sciences 1 December 2001. More...
Epidemiology of breast cancer: an environmental disease?
Sasco reviews several studies through 2001 on the epidemiology of breast cancer to document geographic trends and identify risk factors. 1 May 2001. More...
A reanalysis of the data from a controversial study published in 1992 on declining sperm counts confirms the findings.
The original study by Carlsen et al. found a 50% decline in sperm density over the past 30-50 years. Further analysis of these studies supports a significant decline in sperm density in the United States and Europe, with some intraregional differences. Environmental Health Perspectives 7 November 2000. More...
Scientists review the growing body of evidence on the potential effects of environmental toxicants on female reproduction in laboratory animals, wildlife, and humans.
Chemical exposures may cause alterations in reproductive behavior and contribute to reduced fertility, pregnancy loss, growth retardation, birth defect, and ovarian failure. Data on these associations in humans are equivocal and often controversial. The reasons for ambiguous findings in human studies are unknown but likely include the fact that many studies are limited by multiple confounders, inadequate methodology, inappropriate endpoints, and small sample size. Fertility and Sterility 8 October 2000. More...
False assumptions in fertility studies skew results and make comparisons invalid.
Measurements of how long it takes for a couple to become pregnant are used to estimate the rate of subfertility. Many of studies assume that couples remain equally persistent in trying to become pregnant over time. However, couple behavior is influenced by a number of factors which are often not accounted for in fertility studies. Human Reproduction 1 October 2000. More...
An expanded analysis of studies published from 1934-1996 strongly confirms a decline in sperm density.
This new study re-analyzed a data set first published in 1992 by Carlsen et al. but increases the sample size by 2/3rds compared to the original paper. This analysis adds papers published subsequent to 1990, and then adds a series of papers revealed by additional reviews of existing literature. The original finding is upheld, with a decine in sperm remaining highly significant statistically in the expanded data set. 1 October 2000. More...
A historical review of male reproductive outcomes and xenoestrogens is published after a workshop in Copenhagen in January 1995.
After reviewing the literature at the time the cautious conclusions were that there are declines in sperm counts, increases in testicular cancer, and in certain part of the world increases in hypospadias and cryptorchidism. The workshop also reviewed the literature on environmental chemicals with known estrogenic effects (as of January 1995). Environmental Health Perspectives 6 August 2000. More...
Water contamination in Santa Clara County, California during the year 1980-81 was associated with poor pregnancy outcomes.
Drinking water in one census tract was possibly contaminated by the organic solvent, trichloroethane. In this census tract there was over a 2-fold increase in pregnancy loss and 3-fold increase in birth defects. Because this study did not precisely measure the dose or timing of exposure these results remain inconclusive. American Journal of Epidemiology 5 May 2000. More...
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