META-ANALYSIS Infertility Infertility and the risk of adverse pregnancy outcomes: a systematic review and meta-analysis

and title level. Of these, 179 were identified by either reviewer as being eligible for full-text review. After excluding duplicates and records that clearly failed to meet the study selection criteria (n 1⁄4 90), a total of 89 full-text articles were assessed for eligibility. Figure 1 shows the flow diagram of the literature search process and results. After careful review of all 89 full-text articles, a total of 17 met all inclusion criteria (Tuck et al., 1988; Varma et al., 1988; Hill et al., 1990; Bhalla et al., 1992; Joffe and Li, 1994; Henriksen et al., 1997; McElrath and Wise, 1997; Wang et al., 2002; Basso and Baird, 2003; Thomson et al., 2005; Cooney et al., 2006; Zhu et al., 2007; Romundstad et al., 2008; Jaques et al., 2010; Raatikainen et al., 2010a,b; Ranta et al., 2010; Wisborg et al., 2010) with one study (Romundstad et al., 2008) included only in the qualitative synthesis and not in the meta-analysis. We excluded the Romundstad article from the quantitative synthesis as infertility in the index pregnancy was inferred based on previous history of conceiving a sibling with ART rather than on clinical data of current/index pregnancy. Characteristics of the included studies are summarized in Table I.