How do you get your society's population to grow in The Giver?

In the communities where The Giver takes place, population is regulated and steady.  The only people in the society who can give birth to babies are birthmothers.  It is not known how birthmothers become pregnant.  It would be consistent with the systematic approach to almost everything in the society to assume that birthmothers are impregnated through some form of artificial insemination.  A limited amount of children are born each year to birthmothers.  A family unit...

In the communities where The Giver takes place, population is regulated and steady.  The only people in the society who can give birth to babies are birthmothers.  It is not known how birthmothers become pregnant.  It would be consistent with the systematic approach to almost everything in the society to assume that birthmothers are impregnated through some form of artificial insemination.  A limited amount of children are born each year to birthmothers.  A family unit may not have more than two children.  No one chooses to become pregnant.  No one becomes pregnant unintentionally.  Though family units have male and female spouses, sexual desires are regulated by medication.  It is unlikely that adults in the community know what sex is because of how knowledge is regulated.

In order for the population to increase, more birthmothers would be needed.  This would create a shortage of workers for other occupations because of the already limited population, which would create problems.  Another way to increase the population would be for birthmothers to be required to have more babies during their careers.