Hanging upside down

My fiance mom told him to hang me upside down when we are done having sex. She claims that what her and her husband did for her to get pregnant. She wants him to give her a grandbaby. We have been trying for ten months. I just downloaded this app today. Im fertile now. So we had sex with him on top and my legs in the air. He put a pillow under me for a few minutes. But im wondering if hanging upside down really works.