Vesper is one of Lifelines' additional assessments.
This assessment is a collaboration between Lifelines and the Radboudumc centre of expertise on late effects of childhood cancer (SKION LATER), in association with the UMCG department of reproductive medicine.
The goal of the assessment is to quantify male fertility in the general population using a fertility questionnaire, semen analyses, and plasma testosterone measurements. The results can be used as control values in fertility research, for example on cancer-related infertility.

Vesper started in Q3 of 2019 and will run until 400 male participants have finalized the protocol.
Participants between 18-55 years old are invited:

• to fill in a digital questionnaire about their family composition, family planning, and fertility
• to visit the UMCG blood sampling policlinic for the donation of a blood sample and
• to visit the UMCG policlinic of reproductive medicine to produce a fresh semen sample, which will be analyzed the same morning.

Inclusion criteria were:

• Male
• 18-55 years old

Exclusion criteria were:

• Being vasectomized
• Working nightshifts
• Survivor of childhood cancer