Birth Control

Question
Rav Bar-Hayim,
I have family members with young children 2 or 3 below the age of 4 each. The have been told that they must get a heter from a Rav to use birth control to pace the frequency of births.
Also they must get a heter if they at some point want to have no more than 3 or 4 children. Each has some considerations about the stress on the mother in working (needed to support them) while raising this larger number of children . With incomes what they are in Israel, at least one of the families is unable to manage without both parents working.
What is the proper approach to these Questions from a halachic viewpoint?

Response
Shalom
The requirement for P’ru U’R’vu is one boy and one girl. If a couple has a boy and a girl, they may certainly use birth control in the situation that you describe.
Even if a couple does not yet have one boy and one girl but do have children and are finding things difficult at the moment, they may use birth control for a time, based on their circumstances, in consultation with a competent Rav.
Kol Tuv
Rabbi David Bar-Hayim