Probably if you managed to find 1, the employer will most likely bargain with you like Great SG or Warehouse Clearance Sale.
But there are ok employers out there too, thou they will bargain as well, as long as it's not too much to ask for, still can consider. My wife was such example. She tendered without the knowledge of her pregnancy, we only knew of it when she was serving her notice.
She was up front with her new employer who had the impression that she wasn't pregnant and the new employer bargained.
We came to an agreement for 2 months paid maternity instead of 4, 1st month by employer, 2nd month by govt. Thou we lamented abt the bargain, it was the best she could get in her industry of childcare.
We decided to trust her new employer and luck was probably on her side, it's been nearly 2 yrs and she is more than happy and satisfied with her new employment and her employer is constantly taking of staffs well being, very family oriented kind of workplace.