Study design is an internetbased prospective cohort study on lifestyle and fertility in Danish reproductive age women and men. Participants are enrolled during the period where they try to achieve pregnancy – a unique feature of this study compared to other cohort studies on reproductive age women where participants are recruited once they have become pregnant.


Participants are primarily recruited by online methods like banner advertisements on different homepages, mentioning in newsletters and blog posts. They sign up for the study on the SnartForaeldre homepage and fill in the questionnaires online. Enrollment is based on completion of a comprehensive baseline questionnaire, which takes an average of 22 minutes.

Eligibility criteria

Danish residents can participate in if they are:

  • Aged 18 to 49 (females) or 18+ (males)
  • In a stable relationship with a partner of the opposite sex
  • Not using any kind of contraception
  • Trying to achieve pregnancy
  • Not in any kind of fertility treatment


Female participants are asked to complete:

  • A comprehensive baseline questionnaire
  • A food frequency questionnaire
  • A follow-up questionnaire every 8 weeks until pregnancy occurs or for 12 months
  • A short pregnancy questionnaire if they get pregnant

Male participants are asked to complete:

  • A comprehensive baseline questionnaire
  • A food frequency questionnaire

Link to registry data

Using the civil registration number, a unique 10-digit number assigned to each Danish resident, data from the selfreported questionnaires can be linked to data from several nationwide registries. This linkage allows for the collection of additional data on potential confounders and outcomes of interest, as well as the independent assessment of the validity of some of the self-reported data, including prescription drug use, reproductive history, and socio-demographic variables.

Contact us

Department of Clinical Epidemiology
Aarhus University Hospital
Olof Palmes Allé 43-45
8200 Aarhus N

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