Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) recurrent hydatidiform mole ?
    ### Response:
    Recurrent hydatidiform mole occurs when women have at least two abnormal pregnancies described as hydatidiform moles. A hydatidiform mole occurs early in pregnancy when an embryo does not fully develop and the placenta develops abnormally. The placenta is a solid structure in the uterus that normally provides nutrients to a growing fetus.
    