Spaceborn by Bonnie Vaughan

She traveled millions of miles to Mars, only to be left behind on the ship...

Confined to a spaceship orbiting Mars in 2050, astrogeologist Morgan Zeller watches the main lander descend toward the red planet without her. Her disappointment would be less painful if the crew didn’t resent how she had ruined their mission. Because she turned up pregnant, NASA canceled their experiments so that Morgan can return to Earth before her child is born. But when the lander crashes, endangering the baby’s father, Medical Officer Randall Arnold, and her other crewmates, which include Randy’s ex-lover, Morgan takes off in the emergency lander to rescue them.

During the descent, she sees a mysterious flash of light in the Columbia Hills and later discovers alien artifacts there. Her discovery triggers a colonization race among countries that are fighting over territory on the moon. How can Morgan stop them from bringing war to Mars while she copes with pregnancy and a jealous rival?