Table 1.

Optimal adult levels of vitamin D (as reflected by 25(OH)D levels) from different sources.

Source	Vitamin D level (nmol/L)	Vitamin D level (ng/mL)
Holick (2010) [22]	100–150	40–60
Endocrine Society (2011) [23]	At least >75, aim for 100	At least >30, aim for 40
Amrein et al. (2014) [24]	120–150	48–60
Schwalfenberg and Genuis (2015) [25]	120–150	48–60

No consensus on a specific optimal 25(OH)D level in pregnancy has been achieved.

Emerging agreement that supplemental vitamin D₃ at a dosage of 4000 IU/day throughout pregnancy may be safe and effective [26–30].