I understand your logic, but when people have children they don't have them so that they would lose them, people have children to enjoy seeing them grow into happy well educated adults, it's not about numbers when it comes to mothers and fathers.
I think that palestinians have a lot of children because they know that if they don't, noone will be left in Gaza! People get killed everyday there...
My dad used to tell me, that a few decades ago, in Lebanon, many children died because of the war, disease...etc. So people had many children. He told me that when my grandpa still had five children, people would ask him: Don't you wanna have more children? Because they knew that some of these children will die and they were right, my grandfather did lose five of his kids.
Now that things have changed, people have 2 or 3 kids only...so it is about numbers, when you are not sure wether your kids will reach adulthood or not.
In southern Lebanon, they still have a lot of kids for the same reason. Many of those kids die in the Hezbollah-israeli wars. I've heard of families, who lost all their children in the 2006 war and now they want to have other children...it's about survival.
I don't really agree with their logic, I'd rather have 2 children and take good care of them than having 6 children and losing half of them. But anyways, that's how they think...