Social factors can have a considerable effect on birth rates. Education levels greatly effect birth rates, educated woman are much more likely to be career mind and less intent on having large numbers of children therefore birth rates drop. This also tends to delay marriage and when woman decide to have children in the UK the average age is now 29 years old. It also gives them greater knowledge of birth control which tends to come with the availability of free or cheap contraceptives will also limit the number of children people have, as they have the knowledge of the effects of having children. Urbanization also causes a fall in birth rates as it gives woman a greater choice in life compared to those in rural areas. Politics can also effect birth rates polices such as China's one child policy limits birth rates through government incentives and rulings. These social factors will cause a fall in birth rates although there are many others that cause an increase in birth rates. many of the opposites of the social factors i have commented of above have the opposite effect lack of education and contraception tends to mean high birth rates.
Culture can have profound effects on birth rates and religion is a key aspect of this. Countries such as Saudi Arabia that have a strict sharia law have monumental birth rates as they forbid the uses of contraceptives. This also affects many Catholic countries, however this is more prevalent in poorer religious rich European countries such a Spain have very low birth rates, its fertility rate is 1.47 this is compared to the less developed Catholic Brazil that has a fertility rate of 1.91.
I believe that economic factors have the greatest effect on birth rates as in the richer MEDC's birth rates tend to be very low such as in Germany where it is 8.25% compared to the LEDC Chad which has a staggering birth rate of 45.73%. In the poor LEDC's children are often seen as a valuable commodity as they can provide an income at an early age working in factories and the like providing for their family. In MEDC's there is ample family planning which is the ability to plan the size of family you want using contraception and free healthcare's well as basing the size of your family on your annual income. Birth rates also fluctuate with the strength of the economy when we are in an economic downturn babies are seen as a burden consequently the number of births drop as people put of having a baby until they are confident they are in a good finical situation.