Sounds like this could be Bloodchild by Octavia E. Butler, originally published in the June 1984 issue of Isaac Asimov's Science Fiction Magazine.
The Wikipedia synopsis is broadly consistent with what you described:
"Bloodchild" describes the unusual bond between a race of insect-like lifeforms called the Tlic and a colony of humans who have escaped Earth and settled on the Tlic planet. When the Tlic realize that humans make excellent hosts for Tlic eggs, they establish the Preserve to protect the humans, and in return require that every family choose a child for implantation. A human thus implanted is called N'Tlic.
The story is narrated by Gan, a young boy chosen before birth to carry the eggs of a female Tlic named T’Gatoi. Gan and his sisters perceive being a host as a privilege; however, their elder brother Qui disagrees, having witnessed an N’Tlic birth when he was young. Gan's own opinion changes when he is forced to help T'Gatoi perform an emergency cesarean section on a pregnant male N'Tlic named Bram Lomas, who, abandoned by his Tlic, is being eaten alive by his hatched larvae. Gan uses an illegal rifle to kill an Achti, a large animal kept on the Preserve, to provide nonhuman sustenance for the larvae.
After witnessing the graphic surgery, Gan has second thoughts about being a host and entertains suicide rather than impregnation. He questions T’Gatoi about the relationship between humans and the Tlic. T'Gatoi, who must begin to lay her first eggs that night, asks Gan if she should impregnate Gan's sister instead. However, Gan consents to impregnation on the condition that T'Gatoi allows the family to keep the illegal gun. As T'Gatoi impregnates Gan, she lovingly promises him that she will take care of him and will never abandon him.
There's a preview of a book containing the story here.
And you can listen to an audio version of it here. (Warning: it's pretty gruesome in places.)
