<prompt> True regarding maternal plasma osmolality during pregnancyMaternal plasma osmolality decreases early in pregnancyMaternal plasma osmolality increases throughout pregnancyMaternal plasma osmolality does not change during pregnancyMaternal plasma osmolality is affected most by increases in sodium  <response>: Increased water retention in pregnancy is normal physiological change of pregnancy. It is mediated by fall in plasma osmolality induced by resetting osmotic thresholds for thirst and vasopressin secretion. 