Look out foreign ovum, that's an American sperm headed your way.
Sperm from the United States is making its way overseas in great quantities. According to this article on The Verge, tens of thousands of vials of sperm depart the country every year. The reasons, say Brooke Jarvis include:
Good ethnic diversity. The immigration history in the United States means a lot of ethnicities are represented. Jarvis says, "For would-be mothers from other parts of the world, this can give US product a leg up over places like Denmark, another sperm exporting powerhouse."
High standards. Donors are screened and FDA regulates sperm as if it's human tissue like organs. Once a sample is produced, the sperm are counted under a microscope to determine if it's of good quality. If there are more alive cells then dead ones, the sample gets a passing grade. It's put into a centrifuge that removes blood cells, seminal fluid and other unwanted particles and then frozen in liquid nitrogen.
Large donor pool. Because men can donate anonymously and be paid for doing so, there is a larger donor pool than in other countries.
Interestingly enough, donors must give permission for any future children to contact them if they want to, once they turn 18. The permission is part of a system called Open ID and reduces the number of men who are donating simply to make a quick buck.