Figure 4.

Vitamin A deficiency is a common problem during early pregnancy. A: as per WHO standards, retinol levels for nonpregnant people are greater than those for pregnant people due to the increased demand for retinol during pregnancy (118). B: using the National Health and Nutrition Examination Survey (NHANES), ∼7% of people of child-bearing age have retinol levels that would be considered insufficient or deficient during pregnancy (117). C: during early pregnancy, ∼38% of people had retinol levels that would be considered insufficient or deficient (107).