Why are birth rates higher in lower economically developed countries?

There are a number of reasons for this such as:parents want some children to survive, and thus they have more. Parents want to have more children so that in the future they have a higher chance of some money coming in. Parents in the LEDC's are poorer and disease rates are higher, thus in trying to get the best for their family, they often have more children. Education is also a factor because people in LEDC's are not too well educated, and thus do not know that there are many methods of affordable birth control. Most of the reasons in this category revolve around money, education, and disease levels (by extension, mortality rates).