Birthmother (Also known as Vessels) is the role given at the Ceremony of Twelves to a female.
Their job is to provide children for the community. They are not allowed to have children (to take care of) of their own, nor have spouses afterward. They also cannot take the pills while pregnant, likely due to hormones. Out of all the professions, they require the least training, along with Laborers. After 3 years of being a birthmother, they become Laborers. Before they become Laborers, they have a very luxurious, yet boring, life being a Birthmother. Birthmothers hold low profiles in the community.
While giving birth, they wear masks to prevent them from seeing the newchildren. They also wear masks to prevent them from seeing their partner during sexual intercourse (3 Different Partners each for the 3 years). Most Birthmothers give birth naturally, but in Claire's case, she had to have a Caesarean section.