Fig 1.
Frequency distribution of the 25(OH)D measurements.
25(OH)D concentration is shown as a skewed distribution, and most of the values are less than 30 nmol/L.
Table 1.
Levels and percentages of 25(OH)D measurements in pregnant women, among season and age group.
Fig 2.
Proportions of different vitamin D categories in the study population.
Fig 3.
Histogram of 25(OH)D measurements classified by season and age group.
The 25(OH)D levels in pregnant women were highest in the summer season and the lowest in the winter season. For different seasons, the 25(OH)D level in the 30–35 year age group was higher than that in 18–24 and 25–29 year age groups.
Fig 4.
Trends in 25(OH)D results and in air temperature variation.
From January 2011 to June 2012, the 25(OH)D levels and average monthly air temperature values showed regular variation and the shapes of the curves were consistent with a sinusoidal pattern.