Overall, it appears that pregnant adolescents make the same adaptations as pregnant women, and there is no evidence of adverse effects of pregnancy on BMD measures among adolescents.

The EARs are thus 800 mg/day for pregnant women and 1,100 mg/day for pregnant adolescents. Likewise, the RDA values for non-pregnant women and adolescents are applicable, providing RDAs of 1,000 mg/day and 1,300 mg/day, respectively.

The EAR for non-lactating women and adolescents is appropriate for lactating women and adolescents based on (1) the strong evidence of physiologic changes resulting in a transient maternal bone resorption to provide the infant with calcium (Kalkwarf et al., 1997; Specker et al. 1997; Kalkwarf, 1999) and (2) evidence from RCTs and observational studies that increased total calcium intake does not suppress this maternal bone resorption (Cross et al., 1995; Fairweather-Tait et al., 1995; Prentice et al., 1995; Kalkwarf et al., 1997; Laskey et al., 1998; Polatti et al., 1999) or alter the calcium content of human milk (Kalkwarf et al., 1997; Jarjou et al., 2006). Post-lactation maternal bone mineral is restored without consistent evidence that higher calcium intake is required, as based on two RCTs (Cross et al., 1995; Prentice et al., 1995) and several observational studies (Sowers, 1996; Kovacs and Kronenberg 1997; Kalkwarf, 1999).

Adolescents, like adults, resorb bone during lactation and recover fully afterward with no evidence that lactation impairs achievement of peak bone mass (Chantry et al., 2004).

The EARs are thus 800 for lactating women and 1,100 mg/day for lactating adolescents. Likewise, the RDA values for non-lactating women and adolescents are applicable, providing RDAs of 1,000 and 1,300 mg/day, respectively.

The EARs, RDAs, and AIs for vitamin D are shown in Table 5-3 by life stage group. The identical EARs across age groups are notable and, as discussed below, reflect the concordance of serum 25OHD levels with the integrated bone health outcomes as well as the lack of an age effect on the simulated dose–response. Studies used to estimate these values have been included in Chapter 4 in the review of potential indicators.

While at the outset the consideration of vitamin D requirements recognizes that humans are physiologically capable of obtaining vitamin D