All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The correct opinion is that there is no Sharee’ah evidence to prove that a woman cannot get pregnant during the fist sixth months after delivery; on the contrary the actual fact proves that this is possible.
However, you may refer to the specialist doctors in this field for more information. For more benefit, please refer to Fatwa 87724 and 82154.
Allaah Knows best.