for sodium should be less than 2.3 g (100 mmol)/day. However, data are insufficient to precisely define this level, and many in this age group are under medical supervision due to hypertension, and thus the UL would not apply. In this setting, the UL for sodium and for chloride remain the same as for younger individuals.

According to some authorities, pregnant women retain sodium. Hence salt restriction and prophylactic diuretics have been prescribed to avoid the appearance of de novo hypertension during gestation (Brown and Gallery, 1994; Chesley, 1978; Collins et al., 1985; Lindheimer and Katz, 1985, 2000; Steegers et al., 1991a). Alternatively, data suggest that the pregnant woman may be prone to subtle salt wasting and thus providing additional sodium has been suggested in order to avoid preeclampsia (Robinson, 1958). Still another view is that pregnant women handle ingested sodium similar to the way they do in the nonpregnant state, albeit around new set points for extracellular volume and for volume-influencing hormones (Brown and Gallery, 1994; Lindheimer and Katz, 2000; Weinberger et al., 1977).

Hypertensive disorders during pregnancy are an important cause of maternal and perinatal morbidity and mortality. Among these disorders are chronic hypertension that antedates the pregnancy, gestational hypertension, and preeclampsia. Preeclampsia is a serious condition characterized by the occurrence of hypertension, edema, and proteinuria after 20 weeks of gestation in previously nonhypertensive women. While the pathogenesis of preeclampsia remains uncertain, in the past attention has focused on nutritional factors, particularly a high sodium intake and low calcium intake as possible etiological factors. In fact, low sodium diets have been routinely prescribed as a means to prevent preeclampsia and its complications (Churchill and Beevers, 1999).

However, recent clinical research that included both observational studies (Franx et al., 1999; Morris et al., 2001) and clinical trials (Knuist et al., 1998; Steegers et al., 1991b; van der Maten et