Angry with the baby for interrupting her sleep, the maid picked up the child before dropping her back into the cot.
Indian national Lalkhawngaihi, 24, also forcefully lifted the nine-month-old baby out of the cot by her right hand.
The maid was jailed for six weeks yesterday after pleading guilty to one count of voluntarily causing hurt to the little girl in a Choa Chu Kang flat.
The girl's 25-year-old mother had hired Lalkhawngaihi on Aug 2 last year. Her duties included taking care of the baby.
The mother cannot be named to protect her daughter's identity.
Some time in early April, the mother instructed the maid to feed her daughter whenever she woke between 3am and 5am.
At around 4.50am on April 10, the baby woke up and started crying. Lalkhawngaihi, who was sleeping in the same room, went to the cot and picked the baby up.
After carrying her for a short while, she dropped her into the cot from a height of about 15cm.
The maid's actions were later seen by the baby's parents, who had a closed-circuit television camera (CCTV) installed in the room.
Deputy Public Prosecutor (DPP) Winston Man said: "The victim appeared stunned after being dropped from this height.
"The accused acted in this manner as she was angry and frustrated at the victim for crying and disturbing her sleep.