36 weeks, 4 days

Hi! Ask ko lang if lahat ba nirerequire mag-undergo ng nonstress test (NST) pag last trimester na. 36 weeks 4 days na tiyan ko and my OB asked me to have the test next wk, sa next checkup ko. Is it done for all pregnant or pag may nakita lang na problem kay baby? Though sabi naman ng OB ko last checkup ok heartbeat ni baby.