There is a certain level of absurdity to this discussion. Can we say no to the spark of life God provides? Well, I suppose my answer is to that question is another question: Aren't we all Calvinists? Do you really think we can frustrate God's plan to the extent that He is incapable of creating more people? Can't God raise children for Abraham from rocks? I doubt He would be seriously deterred by birth control if He were bent on the purpose of giving someone another child. After all, He gave one to Mary, and she was a virgin.
But to take this argument down to a more practical level (please, let's have no more nonsense about refusing to allow God to create life) the circumstances in which we find ourselves are the providence of God. He expects us to be wise stewards of what He has given us.
I would be a little cautious with the assumption that having more kids and crowding them places or expecting them to rise to the challenge of caring for a sick or dying mother is a good idea. I have known that to be the case in several situations, and I have known some deeply embittered and/or psychologically damaged children to result from it. My mother had fifteen brothers and sisters. The oldest two are what I would characterize as "broken." The oldest (my aunt) especially suffered from bulimia, anorexia, panic attacks, etc. She had to care for all her brothers and sisters, often while her mother was ill. She has never really recovered from playing "mom" since the age of six. When she was ten, she pulled the body of her little brother out of a drainage ditch after he drowned while she was trying to babysit six children and lost track of him. She would go into hysterics in her early teens about how she needed to learn to drive so that she could get the younger children to the hospital. She nearly starved herself to death with her obsession to save food for the other children (the family was often short on food).
I was the oldest daughter in a family of nine, and I babysat kids since I was six also. I always say I never got to be a child, because I was always taking care of other children and my mother (who suffered serious bouts of postpartum depression, among other things). I can't tell you how often I wished she'd stop having kids, so I could get some sleep at night. Even as much as I loved my siblings, I was exhausted all the time. I always had at least one baby on my arm, while I was trying to do homework, and I was often up at night taking care of sick kids, and then teachers wondered why I was dozing off in class. I was troubled by my mother's increasing insanity as she spoke to angels and said we were all going to have our heads cut off.
So as someone who has seen the other side of this, let me spell it out plainly: The Bible forbids vexing your children. Children are vexed by their parents having a lack of common sense. Children are vexed by mothers who knowingly put themselves in serious danger psychologically or physically. Children are vexed by having too many expectations put on them at too young an age. Children are vexed by parents who put their own responsibilities onto the children and expect the children to pick up the slack or deal with an awful situation that does not need to happen. Adults should not use Scripture to avoid their own responsibilities. As a parent, your responsibility is to be a parent. When you are not a parent and your kid has to clean up after you, this is not so much "God working things out" as it is you dropping the ball.
'm not suggesting this applies to anyone in particular on this thread, but just a general common sense idea: If you are mentally ill, then work on that before you consider having more kids. Your kids need you to be sane. If your marriage is broken down and you are on the verge of divorce, work on that before you have more kids. If your finances are such that having another child would put you in serious debt, then work on your finances before having more children. Consider the needs of the children you already have. The command to be fruitful is a great commandment, but like all commandments (except the one to love your God), it is qualified and balanced with other commandments. Just as we would not tell someone to go out and sell all he has and give the money to the poor in every situation, we shouldn't tell someone to be fruitful and multiply always no matter what.
If the second greatest commandment is to love our neighbor as ourselves, then our nearest neighbors are our children, and love requires that we treat them as we would want others to treat us--not expecting them to be tiny adults or to manage our problems for us. I hope this is not too harsh, but I think it needs to be said. Lots of kids does not necessarily equal a happy well-adjusted family. To this day, both my mother and my grandmother think they were heroes for raising huge numbers of children. Many of their children have a totally different perspective. We remember how dirty we always were because no one bathed us, and we remember how we had to beg food from the neighbors. I remember my brother cracking his skull from his forehead to his ear when he fell off a construction scaffold, and my mother leaving him on the couch because she was too out of it herself to take him to the hospital until he finally started vomiting enough that she worried he would ruin the couch.
I'm not suggesting that anyone on this thread is that crazy. But there are times to encourage people to have kids, and there are times to say, "Look, until you can take better care of the kids you have, maybe you should take some measures to avoid having more." The world is an odd place, and to think that everyone is able to have and raise huge numbers of children is patently absurd. So minimally, think hard about how it will affect your other children if you are too sick to take care of them for nine months. Think how it would affect them if you died. And don't provoke your children to wrath.