Calculation: (7.5 kg/270 days) × 470 mg/kg × 2.5 = 33 mg/day (rounded up to 35) This value is to be added to the EAR for the woman's age group.

EAR for Pregnancy

All ages

+ 35 mg (1.5 mmol)/day

Based on the 1994 CSFII intake data for 33 pregnant women and adjusted for day-to-day variation (Nusser et al., 1996), the median magnesium intake of pregnant women is 292 mg (12.2 mmol)/day, and the seventy-fifth percentile of intake is 332 mg (13.8 mmol)/day (see Appendix D). The EAR of 290 mg (12.1 mmol)/day for pregnant women ages 19 through 30 years and the EAR of 300 mg (12.7 mmol)/day for pregnant women ages 31 through 50 would fall close to the median of magnesium intake. The seventy-fifth percentile of intake, 332 mg (15.3 mmol)/day, is near the magnesium EAR of 335 mg (15.2 mmol)/day for pregnant women ages 14 through 18 years.

Determination of the RDA: Pregnancy

The variance in requirements cannot be determined from the available data for pregnant women. Thus a CV of 10 percent is assumed. This results in an increase in the RDA for pregnancy for magnesium as follows:

EAR for Pregnancy

 

14 through 18 years

335 mg (14.0 mmol)/day

19 through 30 years

290 mg (12.7 mmol)/day

31 through 50 years

300 mg (12.7 mmol)/day

RDA for Pregnancy

 

14 through 18 years

400 mg (16.7 mmol)/day

19 through 30 years

350 mg (15.0 mmol)/day

31 through 50 years

360 mg (15.0 mmol)/day

Special Considerations

Diabetes Mellitus. Infants of mothers with Type I insulin-dependent diabetes mellitus are at risk of hypocalcemia and hypomagnesemia, possibly due to magnesium deficiency in the mother (Mimouni et al., 1986; Tsang et al., 1976). Lower intracellular magnesium concentrations have been recently reported in women with



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