It's not unusual for a baby to be fussy or upset by bath time -- even if just a week earlier she seemed to enjoy it. Sometimes this change coincides with a developmental milestone like teething. Babies this age are also just beginning to develop fears, which are perfectly normal.
Here are some ideas to make bathing easier on you and your baby:
Beware of the noise. Some parents find that the sound of the water filling the tub frightens their baby, so try bringing your baby to the tub only when it's ready.
Adjust the temperature. Some babies prefer a bath on the warmer side, while others like it a bit cool. Make sure both the water and the room temperature are comfortable: Your baby may be objecting to the sudden feeling of cold air on her naked body as she's transferred to the tub. During the bath, gently pour cupfuls of water over her to keep her warm.
Hold her steady. Remember to gradually introduce your baby to the water, supporting her with your hands so she feels secure.
Keep it fun. Try not to rush bath time -- your baby can pick up on your stress or anxiety, and this can make her fussy, too. Talk or sing to her and encourage her to play with bath toys or plastic containers for pouring.
~Courtesy of BabyCenter