Most men with spinal cord injury cannot ejaculate during sexual intercourse.

The spinal cord is involved with two phases of the ejaculatory process. The first allows semen to move into the urethra. The second allows that semen to be pushed out of the urethra. For all of this to happen, chemical messages need to travel between the brain and the genitals via the spinal cord. But when a man has spinal cord injury, this travel is impaired.

According to the Spinal Cord Injury Information Network, about 90% of men have anejaculation, which means they cannot ejaculate at all during intercourse.
Others have retrograde ejaculation, which occurs when semen travels backward into the bladder.

Some men with spinal cord injury can ejaculate through artificial methods, if their reflex abilities have not been damaged. If a man would like to father a child, sperm can be collected through such methods.