There is no seperate validated questionnaire to assess the knowledge, attitude and practice among pregnant mothers on vitamin D. Self made questionnaire only based on the availability of existing information.
Kindly see the attachment pdf, then you will get some idea regarding the KAP study on Vit. D among pregant mothers.
I'm not sure whether your questions is truly serious or whether it should be reworded.
You will not find a validated questionnaire on this topic, as Senthilvel Vasudevan mentioned above. The best way to handle your question would be to search for specific information with proven clinical evidence and to create your own short questionnaire.
Searching PubMed for ["Vitamin D"[TITLE] AND "pregnancy"[TITLE] AND (review OR meta-analysis OR guideline] will provide you with several number of publications on this topic (see attached document).