The first step in forming a family unit happens when an adult applies to receive a spouse. An applicant might wait for months or even years before a Match is found and approved. Factors such as disposition, energy level, intelligence, and interests must correspond perfectly for a Match to be sanctioned by the Committee of Elders. After the spouses are joined at the yearly Matching of Spouses ceremony, the Match is monitored for 3 years by the Committee before the couple can apply to receive a child.
Children are born to Birth Mothers, women who serve in that capacity for three years and then are assigned to be laborers for the rest of their lives. The children are raised collectively by Nurturers until they are a year old, at which time they are distributed by assignment at the yearly Naming and Placement ceremony among those Matches who have applied for children and been approved.
Families in The Giver are chosen or matched by the community's Committee of Elders. They match parents because they have compatible characteristics and the children they are given are never their own biological children. There are specific members of the community who are chosen to be birth mothers. Children are not given to parents until they are one year old, so they are given to families with suitable temperments for their developing personalities. Everything is designed so there is little or no chance for conflict within the family unit.
There is a birthmother that makes babys. And you are only allowed to have two children in one family a male and a female. I hope that answers your question.