What causes amniotic sac disorders?

Many times, there is no known cause for amniotic sac disorders. Having more than one baby in the womb (as with twins) or having diabetes that developed as a result of pregnancy can sometimes cause a woman to have too much amniotic fluid. If the amniotic sac disorder is that she has too little amniotic fluid, the condition is sometimes caused by a woman being pregnant late in her life. Amniotic sac disorders also sometimes coincide with birth defects, though it is not always clear that they cause the disorders.