My daughter is 34, second pregancy and called to say one of her breast bleed in the shower this morning. What might have caused this.

It could be something as simple as mastitis or as serious as breast cancer. She needs to address this with her doctor as soon as possible. And I would make it sooner rather than later as a breast cancer survivor myself.

I don't mean to scare, but we can never be sure. Please have her contact her doctor.