Sperm Partner 

The person that help you, (or you helped) conscieve a child or multiple children together.

See Baby Momma, Baby Daddy

Sheryl was no more than just a sperm partner to David, who had 7 different sexual partners who happened to father his children.

Sheryl was one of David's sperm partners becuse she accepted his semen into her vagina for 9 months until the baby plopped out.

Sperm Partner by Mr. Dwayne October 18, 2004