Ineffectiveness of antenatal guidance intervention for vitamin D insufficiency and deficiency in pregnant women in Kyoto, Japan.

Aim: The aim of this study was to investigate the vitamin D status among healthy pregnant women in Japan, and to evaluate the effectiveness of the antenatal health guidance intervention for the pregnant women who were informed about their low vitamin D levels.

Methods: We measured the level of 25-hydroxyvitamin D (25[OH]D) using chemiluminescent immunoassay among the singleton pregnant women who received at antenatal routine check-up (8-24 weeks of gestation) with written consent during September 2017-September 2018. The measurement values were informed by the concerned physician and health guidance intervention was given to the pregnant women with inadequate Vitamin D status (25[OH]D < 30 ng/mL). At around 36 weeks of gestation, the measurement of 25(OH)D and a questionnaire regarding behavioral changes after the guidance was conducted.

Results: The average value of 25(OH)D of 1192 pregnant women before the guidance was 14.89 ± 4.85 ng/mL, and the prevalence of sufficient vitamin D status (25(OH)D ≥ 30 ng/mL) was 0.67% (8/1192). Nine hundred eighty-two pregnant women who had inadequate vitamin D status were followed, thereafter-guidance prevalence of sufficiency was 1.02% (10/982); insufficiency, 14.66% (144/982); and deficiency, 84.32% (828/982), respectively. Although the prevalence of deficiency was decreased after guidance intervention significantly, the prevalence was still high and the effect on behavioral changes was a little.

Conclusion: The prevalence of vitamin D sufficient status among pregnant women in Japan was extremely low, which is a serious condition. It was also revealed the effectiveness of the antenatal health guidance intervention for pregnant women was not enough.