S. N. Akhter, A. M. John, A. Sultana, S. Alam, I. A. Rahim, and M. Amrullah, “Association between maternal vitamin D deficiency and pregnancy outcomes: a prospective study”, Int J Reprod Contracept Obstet Gynecol, vol. 15, no. 11, pp. 4469–4475, Oct. 2026.