However, they reached the paltry target of 104 losing five wickets from 17.3 overs to keep their hundred per cent winning record.
The slower balls with a bit of turn caused discomfort for Bangladeshi batters, who showed power hitting in previous matches, and their biggest hitter Afia Prottasha got out only for seven facing 10 balls.
Every other batter reached two figures but none could get past 22-run mark as Bangladesh were reduced to 86-5 and 10 dot balls in a row created pressure.
But Rabeya Khatun and Rani Shaha, who scored 18 and 24, hit two boundaries each to ease the pressure and remained not out to navigate the side home.
Earlier in the day, after losing the toss Bangladesh bowlers failed to pick up wickets in regular intervals and got only four scalps throughout the 20 overs but contained the US girls well under a par score.
Skipper Disha Biswas was the pick of the bowlers getting two wickets while conceding just 13 runs off four overs. Rabeya Khan gave away just 14 runs bowling full quota of four overs and opening bowler Marufa Akter got one wicket conceding 17 runs.
US batter Snigdha Paul scored highest 26 runs but consumed 37 balls while Disha Dhingra made 20 off 39. Bangladesh won their first two matches against Australia and Sri Lanka to seal the super six berth.