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Effect of Environmental Factorson
Human Fertility
By: Siamak Bashar
PhD student in Public Health ( Epidemiology)
Department of Health Sciences
Walden University
Primary and Secondary Infertility
Total Infertility Cases Despite having unprotected intercourse for at least 12 months:
Secondary infertility
30%
Primary infertility
70%Female: Has never conceived
Male: Has never impregnated a female
Female: Has previously conceived but is subsequently unable to do so
Male: Has previously impregnated a female but is subsequently unable to do so
Hatcher RA, Trussell J, Stewart F, et al. 1994
Stewart GK. 1998
Fertility Facts
Frequency: 1 out of 6 couples in the US
Responsibility: 35% female infertility 35% male 20% both 10% unknown
Maternal Age USA20-24 4.1% 30-34 9.4%25-29 5.5% 35-39 19.7%
Healy et al, 1994
40%
20%
40%Female Factors
MaleFactors
Unknown/BothNelson, A.L, Marshall, J.R. 2004.
Among couples with identifiable causes of infertility
What can cause infertility?Unexplained-18%
Female Male
• Ovulation disorders
• Tube/uterus blockage
• Cervix
• Endometriosis
• Other
• Sperm count and defects
• Erectile or ejaculation deficiency
Intrinsic vs. Extrinsic, Environmental
Decrease Human Fertility &
Reproductive Health Level
•Increase percentage of US Women with impaired Fecundity by age ( 1982-2002)•Declining Male Testosterone (Travison et al. J Clin Endocrinol Metab, 2006)
•Increasing Testicular Cancers in the United States ( Shah et al. Journal of Andrology, 2007)
•Decreasing Age of Puberty ( Euling , et al. Paediatrics ,2000)
Environmental Influenceson Human Reproduction
• Environmental Chemical
•Nutrition
•Life style
•Emerging old and starting New Sexual Transmitted Diseases
• Behavioural Factors
•Interaction Among the Factors
Infertility From Public Health Point of View
The WHO estimates that there are 60 million to 80 million infertile couples worldwide
•Core infertility: a certain percentage of couples who would be infertile as a result of conditions that we cannot prevent, treat, or even know
•Acquired Infertility: which generally indicates that there are causes in the community responsible for the excess of infertile couples
FATHALLA, M,(1990). Fertility Overview
Acquired Infertility or Infertility Caused by Environmental Factors
1.Lifestyle factors including: age, weight, smoking, diet, exercise, psychological stress, caffeine consumption, and alcohol consumption
Homan, et al 2007
2. Occupational &Environmental Factors:• Physical: such as Light, Temperature, Altitude, and Radiation• Chemical: Such as Natural or man-made• Biological: Such as Viruses, Microorganisms
3. Behavioral Factors: Such as Stress and Drug addiction
http://humupd.oxfordjournals.org/cgi/content/abstract/13/3/209
Environmental Factors Related to Infertility
•Toxic agents
•Tobacco use
• Alcohol Use
• Radiation
•Sexual Transmitted Diseases Sharpe, R.M., & Franks, S., (2002). Environment, lifestyle and infertility — an inter- generational issue, Nature Cell Biology & Nature Medicine8 (S1), S33- S40
http://www.nature.com/fertility/content/full/ncb-nm-fertilitys33.html
Toxic Agents & Infertility
Male
•Lead reduces sex drive, sperm count•Pesticides reduce sperm count
Female
•Lead poisoning reduces conception rates, associated with fetal wastage
Stewart GK. 1998.
Chemicals&
Their Adverse Reproductive Health Effects•DDT/DDE (a): Reduced parity, impaired lactation, decreased semen quality, impaired fertility, and small-for-gestational-age babies
(a)=DDT/DDE = dichlorodiphenyltrichloroethane/dichlorobischlorophenylethylene
•Dibromochloropropane : Decreased sperm counts & infertility
•Pesticides in general :No apparent effects alone but decreased semen qualityand fecundity, spontaneous abortion, pre-term birth, and small for gestational age in mixtures
•PCB(b): Impaired response to ovulation induction, reduced parity, impaired lactation, and potential reduced fecundability
(b)=PCB = polychlorinated biphenyls
Younglai et al, 2006 & Hruska et al., 2000.
http://humupd.oxfordjournals.org/cgi/content/abstract/11/1/43
Tobacco Use & Infertility
• Decreased rates of conception• Increased rates of miscarriage• Increased risk of ectopic pregnancy• Increased risk of placenta previa• Negative effects on fetus
• Sperm production• Motility• Morphology• Fertilization capacity
Stewart GK. 1998.Bouyer J, et al. Am J Epidemiology. 2003.
Cigarette Smoking and Its Adverse Effects on Infertility
Male:
• Negatively affects sperm production, motility and morphology
• Increased risk of DNA damage
Female:
• Negatively affect the follicular microenvironment and alter hormone levels in the luteal phase
• Early Menopause
• Increased thickness of Zona Pellucida
Homan, G.F. et al, 2007
http://humupd.oxfordjournals.org/cgi/content/abstract/13/3/209
Alcohol Use & Infertility
• Decreased rates of conception• Increased rates of miscarriage• Ovulatory infertility• Negative effects on fetus
• Lower testosterone levels
• Decreased sperm production
• Impotence
Stewart GK. 1998.
Radiation & Infertility
Male
Testicular damage or cancer
Chromosomal aberrations
Female
Ovarian failure
Fetal wastage
Fetal damage
Stewart GK. 1998.
Physical Exertion / Heat & Infertility
Stewart GK. 1998.
Men
Frequent heat exposure can temporarily reduce sperm production, such as welders, fire fighters,
and ceramic workers.
Women
Athletes may experience reversible amenorrhea without
long-term effects
Hruska et al., 2000
Sexually Transmitted Diseases & Infertility
2.3 million infertile couples
15–30%Unable to conceive
Chlamydia: Pelvic inflammatory Disease
Gonorrhea : Pelvic Inflammatory Disease
Human papillomavirus
Donovan P. 1993.
Prevention
Primary Prevention: A public health strategy focusing on primary
prevention ;e.g., through removal of risk factors for infertility such as
early detection and treatment of sexually transmitted infections and,
in particular, Chlamydia infection, Smoking, Overweight, Unhealthy
Life style, Occupation hazard, and Toxic chemical substances.
Center for Diseases Control and Prevention, 2009
http://www.cdc.gov/std/infertility/ReportCongressInfertility.pdf
PreventionSecondary Prevention: Whereas primary prevention is important, infertility diagnosis and treatment are relevant to public health in their own merit.
•First, infertility is an area where health care costs are borne most often by the individual, creating significant economic and racial disparities.
•Second, early diagnosis and treatment of underlying medical conditions (secondary prevention) may lead to effective restoration of fertility.
•Third, infertility treatment, although generally safe, is associated with adverse health outcomes for the mother and the child; epidemiologic surveillance efforts are increasingly necessary to design and implement tertiary prevention programs (i.e., the prevention of adverse outcomes of infertility treatment)
Center for Diseases Control and Prevention, 2009
http://www.cdc.gov/std/infertility/ReportCongressInfertility.pdf
Prevention
•Tertiary Prevention; the treatment of infertility, as well as some of its outcomes, contributes to increasing the cost of health care for all.
Public Health Policy Implications:
Research:
•In the area of primary prevention, research into modifiable causes of infertility should be given high priority. Research is needed to elucidate the mechanisms through which specific medical conditions lead to infertility
• In the area of clinical outcomes research and tertiary prevention, there are few and limited economic studies assessing the cost-effectiveness of infertility treatment, the financial impact of treatment options, and the effect of insurance coverage on access to treatment
•In the area of secondary prevention, research is needed to evaluate the potential benefit of early detection and treatment of conditions leading to infertility, both among couples who are actively seeking a pregnancy and among individuals who may want a child in the future
Public Health Policy Implications
Sharpe & Franks, 2002
•Community Action: Learning about potentially hazardous chemicals in everyday products and in the workplace and their effects on babies in utero are powerful personal motivators toward further education and activism.
Safe Work: for increasing worker safety in work place ,
& Woodruff et al (2008)
1. Reduce permissible exposure levels to chemicals that harm reproduction and development so that they are more in line with environmental exposure limits
2. Exposure assessment and monitoring in occupational settings should be expanded3. Expand occupational health researchers’ access to workers so that health consequences
can be identified and corrected4. Develop alliances that can improve health across different sectors. For example,
making the connection between worker safety and hospital patient safety (concerning phthalates) and fostering alliances between environmental health groups and labour and worker groups
References:
•Hatcher RA, Trussell J, Stewart F, et al. (1994). Contraceptive Technology. 16th revised ed. New York, NY: Irvington Publishers, Inc.
•Healy, D.L., Trounson ,A.O., & Andersen A.N. (1994). Female infertility: causes and treatment. Lancet, 343:1539–1544
•Fathalla, M.F., et al. (1991). Reproductive Health: A Global Overview. Annals of the New York Academy of Sciences, Parthenon Publishing Group. Lancs. UK & New Jersey
•Fidler, A.T., & Bernstein, J. (1999). Infertility: from a personal to a public health
•Bouyer, J., et al. (2003). Risk factors for ectopic pregnancy: A comprehensive analysis based on a large case-control, population-based study in France. Am J Epidemiology [serial on the Internet]; 157(3): 185-194.
•Donovan ,P. (1993).Testing Positive: Sexually Transmitted Disease and the Public Health Response. New York, NY: The Alan Guttmacher Institute.
•Euling, S. Y., et al. (2008). Role of environmental factors in the timing of puberty. Paediatrics; 121 Suppi 3:S167-71
•Homan, G.F., Davies, M., & Norman, R. (2007). The impact of lifestyle factors on reproductive performance in the general population and those undergoing infertility. Human Reproduction .13(3):209-223; doi:10.1093/humupd/dml056
•Shah, M.N., et al. (2007). Trends in testicular germ cell tumours by ethnic groups in the United States Int J Androl: 30:206-13; discussion 13-4.
•Travison, T.G., et al. ( 2007). A population-level decline in serum testosterone levels in American men.J Clin Endocrinol Metab; 92:196-202.
•Younglai , E.V., et al.(2006).Environmental and occupational factors affecting fertilityand IVF success, Human Reproduction Update, Vol.11, No.1 pp. 43–57.
•Stewart, G.K. (1998). Impaired Fertility. In Hatcher R, Trussell J, Stewart F, et al., eds. Contraceptive Technology. 17th revised ed. New York, NY: Ardent Media, Inc.
•Nelson, A.L., & Marshall J.R. (2004). Impaired fertility. In Hatcher R, Trussell J, Stewart F, et al. (Eds.) Contraceptive Technology. 18th Revised Ed. New York, NY: Ardent Media, Inc.
•Infertility: A Public Health Focus on Infertility Prevention, Detection, and Management. Center for Diseases Control and Prevention (CDC): Retrieved from CDC Website Jan 30, 2010: http://www.cdc.gov/std/infertility/ReportCongressInfertility.pdf
•Sharpe, R.M., & Franks, S., (2002). Environment, lifestyle and infertility — an inter- generational issue, Nature Cell Biology & Nature Medicine8 (S1), S33- S40http://www.nature.com/fertility/content/full/ncb-nm-fertilitys33.html
•Wookruff, T.J., et al. (2008). Proceeding of the Summit on Environmental Challenges to Reproductive Health and Fertility: executive summary. Fertility and Sterility, Vol. 89, No. 2.
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