This study aims to eventually assess the usefulness of thermotaxis for sperm selection in routine clinical practice.

As the world's total fertility rate decline, every year more couples require assisted reproductive technologies (ART) in order to achieve their desire to become parents. However, these techniques are not guaranteed solutions and still many couples with unexplained infertility fail to conceive. One of the reasons might be the relative selection of spermatozoa for the following ART. To minimize a poor selection made by the operator and to standardize spermatozoa selection, we suggest a new method might be used in combination with the routine spermatozoa selection techniques.

Thermotaxis might be used in the ART setting as a tool to select the best spermatozoa as human spermatozoa after capacitation responds positively to a temperature gradient change. Moreover, this might be the possible navigation mechanism of spermatozoa in the female genital tract. We hypothesize that spermatozoa selected by thermotaxis behavior might increase the morphologically normal spermatozoa number in the cohort used during ART.

The aim of this study is to evaluate if thermotaxis is a good method for selecting morphologically normal sperm for ART.

Inclusion Criteria:

• Age: ≥18 and <40 years old.
• Spermatozoa concentration >15 x 10⁶ /mL in all sperm analysis performed in the last 24 months.
• Spermatozoa mobility >32% in all sperm analysis performed in the last 24 months.
• Spermatozoa morphology >4% in all sperm analysis performed in the last 24 months.
• Signed and dated informed consent

Exclusion Criteria:

• Use of antibiotics, intravenous illicit drugs, chemotherapy or radiotherapy usage in the last 3 months.
• Active smoking (during the preceding 12 months).
• More than 3 days prior to the last ejaculation.

10 male sperm donors.