European Journal of Epidemiology

, Volume 25, Issue 5, pp 297–304 | Cite as

A successful implementation of e-epidemiology: the Danish pregnancy planning study ‘Snart-Gravid’

  • Krista F. Huybrechts
  • Ellen M. Mikkelsen
  • Tina Christensen
  • Anders H. Riis
  • Elizabeth E. Hatch
  • Lauren A. Wise
  • Henrik Toft Sørensen
  • Kenneth J. Rothman


The attraction of being able to use the internet for the recruitment of an epidemiologic cohort stems mainly from cost efficiency and convenience. The pregnancy planning study (‘Snart-Gravid’)—a prospective cohort study of Danish women planning a pregnancy—was conducted to evaluate the feasibility and cost efficiency of using internet-based recruitment and follow-up. Feasibility was assessed by examining patient accrual data over time, questionnaire-specific response rates and losses to follow-up. The relative cost efficiency was examined by comparing the study costs with those of an alternative non internet-based study approach. The target recruitment of 2,500 participants over 6 months was achieved using advertisements on a health-related website, supported by a coordinated media strategy at study initiation. Questionnaire cycle-specific response rates ranged from 87 to 90% over the 12-month follow-up. At 6 months, 87% of women had a known outcome or were still under follow-up; at 12 months the figure was 82%. The study cost of $400,000 ($160 per enrolled subject) compared favorably with the estimated cost to conduct the same study using a conventional non-internet based approach ($322 per subject). The gain in efficiency with the internet-based approach appeared to be even more substantial with longer follow-up and larger study sizes. The successful conduct of this pilot study suggests that the internet may be a useful tool to recruit and follow subjects in prospective cohort studies.


Internet-based recruitment and follow-up Prospective cohort Pregnancy planning study Feasibility Cost efficiency 



This work was supported by the National Institute of Child Health and Human Development (R21050264); and the Danish Medical Research Council (271-07-0338).

Conflict of interest

None declared.


  1. 1.
    Stampfer MJ, Colditz GA, Willett WC, Manson JE, Rosner B, Speizer FE, et al. Postmenopausal estrogen therapy and cardiovascular disease. Ten-year follow-up from the nurses’ health study. N Engl J Med. 1991;325(11):756–62.PubMedCrossRefGoogle Scholar
  2. 2.
    Hammond EC, Horn D. Smoking and death rates–report on 44 months of follow-up of 187,783 men. By E. Cuyler Hammond and Daniel Horn, 1958. CA Cancer J Clin. 1988;38(1):28–58.CrossRefPubMedGoogle Scholar
  3. 3.
    Burns DM, Shanks TG, Choi W, Thun MJ, Heath CW, Garfinkel L. The American Cancer Society Cancer Prevention Study I: 12-year follow-up of one million men and women. In: National Cancer Institute, Smoking and Tobacco Control, Monograph 8: changes in cigarette-related disease risks and their implication for prevention and control. Washington, DC: National Institutes of Health; 1997. p. 113–304.Google Scholar
  4. 4.
    Garfinkel L. Selection, follow-up, and analysis in the American Cancer Society prospective studies. Natl Cancer Inst Monogr. 1985;67:49–52.PubMedGoogle Scholar
  5. 5.
    Stellman SD, Garfinkel L. Smoking habits and tar levels in a new American Cancer Society prospective study of 1.2 million men and women. J Natl Cancer Inst. 1986;76(6):1057–63.PubMedGoogle Scholar
  6. 6.
    Russell C, Palmer JR, Adams-Campbell LL, Rosenberg L. Follow-up of a large cohort of black women. Am J Epidemiol. 2001;154(9):845–53.CrossRefPubMedGoogle Scholar
  7. 7.
    Formica M, Kabbara K, Clark R, McAlindon T. Can clinical trials requiring frequent participant contact be conducted over the Internet? Results from an online randomized controlled trial evaluating a topical ointment for herpes labialis. J Med Internet Res. 2004;6(1):e6.CrossRefPubMedGoogle Scholar
  8. 8.
    McAlindon T, Formica M, Kabbara K, LaValley M, Lehmer M. Conducting clinical trials over the internet: feasibility study. BMJ. 2003;327(7413):484–7.CrossRefPubMedGoogle Scholar
  9. 9.
    Williams PT. National Health Survey. Available at: cgi-bin/WebObjects/Project. 1997.
  10. 10.
    Etter JF, Perneger TV. A comparison of cigarette smokers recruited through the Internet or by mail. Int J Epidemiol. 2001;30(3):521–5.CrossRefPubMedGoogle Scholar
  11. 11.
    Koo MM, Rohan TE. Use of world wide web-based directories for tracing subjects in epidemiologic studies. Am J Epidemiol. 2000;152(9):889–94.CrossRefPubMedGoogle Scholar
  12. 12.
    Baird DD, Wilcox AJ, Weinberg CR. Use of time to pregnancy to study environmental exposures. Am J Epidemiol. 1986;124(3):470–80.PubMedGoogle Scholar
  13. 13.
    Rockenbauer M, Olsen J, Czeizel A, Pedersen L, Sørensen H, Group E. Recall bias in a case-control surveillance system on the use of medicine during pregnancy. Epidemiology. 2001;12(4):461–6.CrossRefPubMedGoogle Scholar
  14. 14.
    Mikkelsen EM, Hatch EE, Wise LA, Rothman KJ, Riis A, Sorensen HT. Cohort profile: the Danish web-based pregnancy planning study—‘Snart-Gravid’. Int J Epidemiol. 2009;38(4):938–43.CrossRefPubMedGoogle Scholar
  15. 15.
    Frank L. When an entire country is a cohort. Science. 2000;287:2398–9.CrossRefPubMedGoogle Scholar
  16. 16.
    Mikkelsen EM, Sunde L, Johansen C, Johnsen SP. Risk perception among women receiving genetic counseling: a population-based follow-up study. Cancer Detect Prev. 2007;31(6):457–64.CrossRefPubMedGoogle Scholar
  17. 17.
    Olsen J, Melbye M, Olsen SF, Sorensen TI, Aaby P, Andersen AM, et al. The Danish National Birth Cohort–its background, structure and aim. Scand J Public Health. 2001;29(4):300–7.CrossRefPubMedGoogle Scholar
  18. 18.
    Olsen SF, Mikkelsen TB, Knudsen VK, Orozova-Bekkevold I, Halldorsson TI, Strom M, et al. Data collected on maternal dietary exposures in the Danish National Birth Cohort. Paediatr Perinat Epidemiol. 2007;21(1):76–86.CrossRefPubMedGoogle Scholar
  19. 19.
    Hartge P. Participation in population studies. Epidemiology. 2006;17(3):252–4.CrossRefPubMedGoogle Scholar
  20. 20.
    Bonde JP, Hjollund NH, Jensen TK, Ernst E, Kolstad H, Henriksen TB, et al. A follow-up study of environmental and biologic determinants of fertility among 430 Danish first-pregnancy planners: design and methods. Reprod Toxicol. 1998;12(1):19–27.CrossRefPubMedGoogle Scholar
  21. 21.
    Ekman A, Litton JE. New times, new needs; e-epidemiology. Eur J Epidemiol. 2007;22(5):285–92.CrossRefPubMedGoogle Scholar
  22. 22.
    Lenert L, Skoczen S. The Internet as a research tool: worth the price of admission? Ann Behav Med. 2002;24(4):251–6.CrossRefPubMedGoogle Scholar
  23. 23.
    Nohr E, Frydenberg M, Henriksen T, Olsen J. Does low participation in cohort studies induce bias? Epidemiology. 2006;17(4):413–8.CrossRefPubMedGoogle Scholar
  24. 24.
    Rothman KJ, Greenland S, Lash TL. Validity in epidemiologic studies. In: Rothman KJ, Greenland S, Lash TL, editors. Modern epidemiology. 3rd ed. Philadelphia: Lippincott Williams & Wilkins; 2008.Google Scholar
  25. 25.
    OECD(2008) Broadband statistics.Google Scholar
  26. 26.
    Jensen TK, Sobotka T, Hansen MA, Pedersen AT, Lutz W, Skakkebaek NE. Declining trends in conception rates in recent birth cohorts of native Danish women: a possible role of deteriorating male reproductive health. Int J Androl. 2008;31(2):81–92.CrossRefPubMedGoogle Scholar
  27. 27.
    Juul S, Karmaus W, Olsen J. Regional differences in waiting time to pregnancy: pregnancy-based surveys from Denmark, France, Germany, Italy and Sweden. The European infertility and subfecundity study group. Hum Reprod. 1999;14(5):1250–4.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Krista F. Huybrechts
    • 1
  • Ellen M. Mikkelsen
    • 2
  • Tina Christensen
    • 2
  • Anders H. Riis
    • 2
  • Elizabeth E. Hatch
    • 1
  • Lauren A. Wise
    • 1
    • 3
  • Henrik Toft Sørensen
    • 1
    • 2
  • Kenneth J. Rothman
    • 1
    • 4
  1. 1.Department of EpidemiologyBoston University School of Public HealthBostonUSA
  2. 2.Department of Clinical EpidemiologyAarhus University HospitalAarhusDenmark
  3. 3.Slone Epidemiology Center, Boston UniversityBostonUSA
  4. 4.RTI Health SolutionsResearch Triangle ParkUSA

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