1. Statistics Korea. The 2015 birth statistics (confirmed) [internet]. Seoul: Author;2016. [cited 2016 August 24]. Available from:. http://kostat.go.kr/portal/korea/kor_nw/3/index.board?bmode=read&aSeq=355737.
2. Luke B. The rise in multiple births in the United States: who, what, when, where, and why. Clinical Obstetrics and Gynecology. 2004; 47(1):118–133.
Article
3. Lee GR, Park KH, Park JS, Lee WM, Cha JY, Kim HH, et al. Statistical analysis of twin pregnancy for 10 years (1993∼2002). Obstetrics & Gynecology Science. 2003; 46(10):1957–1964.
4. Sibai MD, Baha M. Hypertensive disorders in twin versus singleton gestations. American Journal of Obstetrics and Gynecology. 2000; 182(4):938–942. https://doi.org/10.1016/S0002–9378(00)70350–4.
Article
5. Rauh-Hain J, Rana S, Tamez H, Wang A, Cohen B, Cohen A, et al. Risk for developing gestational diabetes in women with twin pregnancies. Journal of Maternal-Fetal and Neonatal Medicine. 2009; 22(4):293–299. https://doi.org/10.1080/14767050802663194.
Article
6. Goodnight W, Newman R. Optimal nutrition for improved twin pregnancy outcome. Obstetrics and Gynecology. 2009; 114(5):1128–1134. https://doi.org/10.1097/AOG.0b013e3181bb14c8.
Article
7. Kullima AA. Outcome of twin deliveries at the University of Maiduguri Teaching Hospital: a 5-year review. Nigerian Journal of Clinical Practice. 2011; 14(3):345–348.
Article
8. Lee EJ, Kim YH, Kwon JY, Park YW. Pregnancy outcome according to gestational weight gain in twin pregnancies on the basis of the 2009 Institute of Medicine (IOM) recommendations. Korean Journal of Obstetric and Gynecology. 2010; 53(8):687–693. https://doi.org/10.5468/kjog.2010.53.8.687.
Article
9. Kim MJ, Na ED, Lee KJ, Cha DH, Shin JS, Lee HY. Pregnancy prognosis according to prepregnancy body mass index and gestatonal weight gain in twin pregnancies. Korean Journal of Obstetric and Gynecology. 2012; 55(5):300–308. https://doi.org/10.5468/KJOG.2012.55.5.300.
10. Luke B. Nutrition for multiples. Clinical Obstetrics and Gynecology. 2015; 58(3):585–610.
Article
11. Shinagawa S1. Suzuki S, Chihara H, Otsubo Y, Takeshita T, Araki T. Maternal basal metabolic rate in twin pregnancy. Gynecol Obstet Invest. 2005; 60(3):145–148.
12. Rosello-Soberon ME, Fuentes-Chaparro L, Casanueva E. Twin pregnancies: Eating for three? maternal nutrition update. Nutrition Reviews. 2005; 63(9):295–302.
13. Cho SK. Smartphones used for foreign language learning. Multimedia-Assisted Language Learning. 2009; 12(3):211–228.
14. Digieco. Mobile trend of the first half of the year 2015 [Internet]. Seoul: Author;2015. [cited 2015 July 6]. Available from:. http://www.digieco.co.kr/KTFront/report/report_issue_trend_view.action?board_seq=10349&board_id=issue_trend#.
15. Korea gallup. 2012–2017 Research for smartphone use and experience of the game <Pokemon GO> [internet]. Seoul: Author;2017. [cited 2017 February 15]. Available from:. http://www.gallup.co.kr/gallupdb/reportContent.asp?seqNo=813.
16. Jo SJ. Development and evaluation of a smartphone application for managing gestational diabetes mellitus. Healthcare Informatics Research. 2016; 22(1):11–21.
Article
17. Han HM. Development of smartphone application in hospital admission education for mothers with infants on the high risk [master's thesis]. Seoul: Chung-Ang University;2016. p. 70. p.
18. Chung JS. Program evaluation. 1st ed.Seoul: Kyoyookbook;2004. p. 61. p.
19. Lynn MR. Determination and quantification of content validity. Nursing Research. 1986; 35(6):382–386.
Article
20. Kim MR. Development and evaluation of health care smart phone application evaluation tool [master's thesis]. Seoul: Seoul National University;2014. p. 65. p.
21. Korea food & drug administration. Nutrition guide for mothers-to-be [internet]. Seoul: Author;2011. [cited 2011 September 21]. Available from:. http://mfds.go.kr/index.do?mid=700&seq=11675.
22. Korean diabetes association. Six food groups [internet]. Seoul: Author;; Available from:. http://www.diabetes.or.kr/general/food/sub02.php?idx=3.
23. Cho MJ. Development of smartphone educational application for patients with coronary artery disease [master's thesis]. Gwangju: Chosun University;2013. p. 41. p.
24. Park SW, Park JS. Development and evaluation of an infection prevention self-care application for cancer patients with chemotherapy. Asian Oncol Nurs. 2016; 16(4):197–207.
Article
25. Ryu JW. New pregnancy, delivery, infant care. 1st ed.Seoul: Cheongrimlife;2017. p. 83. p.
26. Luke B. Improving multiple pregnancy outcomes with nutritional interventions. Clinical Obstetrics and Gynecology. 2004; 47(1):146–162.
Article
27. Luke B. Nutrition and multiple gestation. Seminars in Perinatology. 2005; 29(5):349–354. https://doi.org/10.1053/j.semperi.2005.08.004.
Article
28. KISA. Results of the research for actual state of national internet use environment [internet]. Seoul: Author;2015. [cited 2015 February 12]. Available from:. http://www.kisa.or.kr/notice/press_View.jsp?mode=view&p_No=8&b_No=8&d_No=1347.
29. Dutta BM. Trusted online sources of health information: differences in demographics, health beliefs, and health-information orientation. Journal of Medical Internet Research. 2003; 5(3):): e21.https://doi.org/10.2196/jmir.5.3.e21.
30. Noh SH, Park JS. Development of postoperative self care mobile app for kidney transplantation patients. Journal of the Korea Academia-Industrial cooperation Society. 2016; 17(12):316–326.
Article