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)

What Is Changing?

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

Thank You

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.