When God said "be fruitful" This was a blessing on them. When He said "and multiply", of course He meant what it says, but then, they fell! They threw away the blessing, and as God told Eve, bearing children would bring pain. At this time, Adam and Eve gave away the 'world' into the hands of Satan, gave away, their "dominion". Not only did they suffer the consequences of their sin, but Creation did also.
The world did not then run under their rule. Where they could have numerous children in a paradise Garden, now they had to fight for every grain they grew,
While I agree God wanted us to have children, at the moment our children are brought into a sinful world and where they would never have had such a thing as miscarriage, birth defects, etc, in Eden, They have them here. Where they could have had many children and kept them all, that is not so possible after the fall. In counties like India, the population is so dense ,because under colonial rule certain well thinking Christians told them it was wrong to practice any kind of control & even feed their children from mothers breast, and sold them on the idea of powdered milk. Of course, breast feeding is in it's own way, a contraceptive, it actually lowers the chance of pregnancy quite well. The colonials did not like to see mothers still breast feeding infants at 3, sometimes to 5 or 6 yrs. They sold them powdered milk, and the population began to boom! And the powdered milk cost money! In the end, they did not have the money to pay for all the milk they needed, and some of their kids starved. It was so called Christians that sold them the powdered milk.
What is the lesson?
Having children is a blessing, but what good are we to them, if we can't even afford to feed them all? Look at places like Ethiopia and others where they have big famines occur. Children starving to death and dropping like flies. There is enough food in this world to feed every human being, and yes aid is sent, but not enough, because money gets in the road, and some of the people who rule over these famine countries steal the aid and sell it!
If you want people to not practice contraception, then make sure there is enough for all those children, or watch many starve.