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Tiwari A, Chan KL, Fong D, Leung WC, Brownridge DA, Lam H, Wong B, Lam CM, Chau F, Chan A, Cheung KB, Ho PC.Tiwari A, et al.BJOG. 2008 Feb;115(3):377-84. doi: 10.1111/j.1471-0528.2007.01593.x.BJOG. 2008.PMID: 18190375Free PMC article.
Smith RD, Hung SC, Goh J, Ip HL, Fong DYT, Ali S, Wilson CA, Lok KY.Smith RD, et al.BMJ Open. 2021 Oct 11;11(10):e048764. doi: 10.1136/bmjopen-2021-048764.BMJ Open. 2021.PMID: 34635517Free PMC article.