Is it considered fever if your temp is 37.9 c?

Fever?: For most adults, oral temp over 38 C (100.4F) is a fever. Rectal or ear temp over 38.3 C (101 F). For kids, rectal temp of 38 C (100.4) or higher is a fever.

It's a low grade fev: 37.9 C translates to 100.2 F so it is considered a low grade fever.

Temperature: 100.22 F (37.9 C). If this is an oral temp on an adult 100.4 is considered a fever.