STORY HIGHLIGHTS
Yingluck was admitted to the hospital Monday night and will miss the weekly cabinet meeting Tuesday, spokeswoman Tithima Chaisaeng said.
Deputy Prime Minister Yongyuth Vichaidith will chair the meeting in her absence, the spokeswoman said.
Yingluck was elected the nation's first female prime minister in August.
She is the younger sister of one of Thailand's most polarizing political figures, former Prime Minister Thaksin Shinawatra, who was ousted in a 2006 military coup.
He left the country two years later after he was convicted on conflict of interest charges -- accusations he denies.
Yingluck's critics worry she will do her brother's bidding -- something she has denied.