How would trental (pentoxifylline) cause sperm hypermotility?

Focus on what helps. There is no evidence that any medicine taken by men will increase the chance that their female partner will become pregnant. Trental, (pentoxifylline) clomid, tamoxifen, anastrozole, vitamins, supplements... All not proven to increase the pregnancy rates. If you have 10 million motile sperm you can try naturally if possible or with insemination. If not then ivf.