Why do you even need to ask?
I'll break it down into basic maths using a hypothetical excample. If Couple X has 3 kids and lose one as an infant, and Couple Y have 2 kids and lose none, what is the most important factor in not dying out? Merely giving birth, or also upbringing the children?
And let's not forget that upbringing a child will demand lots of resources. So not only is Couple X not better off than Couple Y, but they've also been spending energy that - from the point of biology - was in hindsight pointless.
Moving over to real life, it's in any case clear that the Western world is nowhere near dying out anyway, and that it's merely a transition period we have while we have a lot of old ones who suddenly survived after concepts like medicine and hygiene were introduced, but before the birth rates were going down to reflect the decreased infant mortality rate. So once the "old wave" of the next 30 years are gone, then I expect the population rates to get more stable almost by default.