onism and Bartter’s syndrome (August and Lindheimer, 1999; Lindheimer et al., 1987). On the other hand, if the kidneys of pregnant women resist kaliuretic stimuli, one might speculate that women with underlying disorders that impair their ability to excrete potassium may be jeopardized by gestation. In this respect, there have been isolated descriptions of abnormally high potassium concentrations in pregnant women with sickle cell anemia and normal serum creatinine concentrations (Lindheimer et al., 1987), and at least one instance where a woman believed to have renal tubular acidosis developed hyperkalemia when treated with a potassium sparing diuretic (Szwed and Clarke, 1982).

Blood Pressure. Intervention trials that tested the effects of potassium intake on blood pressure during pregnancy are lacking. In one observational study, maternal potassium intake was not associated with pregnancy-associated hypertension or pre-eclampsia (Morris CD et al., 2001). One observational study showed that maternal prenatal potassium intake was inversely related to the infant’s diastolic blood pressure at 6 and 12 months of age (McGarvey et al., 1991).

Summary. Overall, potassium accretion during pregnancy is very small and there is an absence of data to suggest that the requirement for potassium is different during pregnancy. Therefore, the AI is set at 4.7 g (120 mmol)/day, the same as for nonpregnant women.

The potassium content of human milk averages around 0.5 g/L (13 mmol/L) during the first 6 months of lactation (see Table 5-9). Average milk production during the first 6 months of lactation is ≈ 0.78 L/d. Thus approximately 0.4 g (10 mmol)/day of potassium is needed for lactation during this period (0.5 g/L × 0.78 L/day =