This is an observational prospective study. The main purpose is to evaluate the stability of the Bilistick system in a humid and hot climate compared to the quantitative test for serum bilirubin (SBR) measurement currently used, the BR-501 total bilirubin meter, kept in a controlled environment.

The secondary aim is to assess the operational feasibility of the Bilistick system in a tropical limited-resource setting, when used by locally trained nurses.

Study procedure:

1. SBR will be measured in parallel with two tests during three distinct seasons. (Cold, hot, rainy). The Blood is from an extra capillary sample taken from a single heel prick done for routine SBR) BR-501 total bilirubin meter, the quantitative test for SBR currently used, will be kept in a controlled environment while the new bilirubin test (Bilistick system) will be exposed to tropical conditions.
2. Trained nurses will use the Bilistick system observed by a qualified laboratory technician; Usability of the Bilistick system by the trained nurses will be evaluated via a 5-point Likert scale questionnaire and focus groups discussions.

Inclusion Criteria:

• Written or thumb print for informed consent from the parent
• Infant born ≥ 35 weeks of gestational age
• Infant who needs a routine SBR measurement
• Infant in stable clinical condition prior to SBR measurement confirmed by the trained nurses

Exclusion Criteria:

The participant will not be enrolled in the study if ANY of the following applies:

• Infant who already had 1 SBR measurement done with the Bilistick system
• Last haematocrit measurement > 65% or no previous haematocrit measurement

Infant seen in WPA clinic during the neonatal period (birth to 28 days of life).