I was listening to a radio show on line where experts are asked various questions on selected topics. This show was on family planning i.e. using birth control.
Rabbi X was asked if it is permitted to limit the number of children one has for financial reasons. His answer: Absolutely yes. No question. If ya can't afford 'em - don't have 'em.
After Rabbi X hung up, Rabbi Y came on and was asked the very same question. His answer - no way. No question about it. It is absolutely forbidden. One must have kids and have bitachon that Hashem will provide. In other words - exactly THE OPPOSITE of what Rabbi X had said.
Then a third Rabbi came on the line and was asked the same question. His response? Very measured, careful and guarded. A lot of words with his conclusion being inconclusive.
My own inclinations go with Rabbi Number Three. It is a VERY complex issue and depends on a lot of factors.
If one does a search on the Otzar Hachochma program with the words תכנון המשפחה many sources could be located.
One thing I have noticed in our days is that usually [not always], poskim who are considered "Modern Orthodox" are more lenient about birth control while the more Charedi are less likely to permit [barring extenuating circumstances]. That in part explains why more "modern" families usually have less children [on average] than Charedi families. Another reason is that many people use birth control and don't even ask a Rov.
I will end with this. Usually, people don't look at a child of theirs and say "It is to bad we had him/her." If a child, G-d forbid dies, a parent will never say "hey, we could only handle six and we had seven, so it's really OK."
Pru U'rivu is stated twice in the Torah. Why twice? Chazal say, once as a commandment and once as a bracha. Children are a bracha.
