Table 2.
General features of the studies
| Studies | Study design | Year of patients’ enrollment | No of infertile smokers (n) | No of infertile non-smokers (n) | Age (years) S/NS |
|---|---|---|---|---|---|
| Al-Turki2014 | Retrospective | 2010–2012 | 90 | 168 | 34.2/34.1 |
| Al-Turki2016 | Retrospective | 2008–2013 | 194 | 322 | 34.6/34.3 |
| Anifandis2014 | Prospective | – | 33 | 98 | 37.9/37.1 |
| Caserta2012 | Cross sectional | 2006–2011 | 200 | 448 | 38.3/38.5 |
| Cui2016 | Prospective | 2013–2015 | 920 | 298 | – |
| Gaur2007 | Retrospective | 2001–2004 | 100 | 100 | – |
| Meri2013 | Retrospective | 2010–2011 | 396 | 564 | – |
| Mitra2012 | Cross sectional | – | 178 | 126 | 40.5/35.0 |
| Trummer2002 | Prospective | 1993–2000 | 478 | 517 | 31.5/33.4 |
| Mostafa2006 | Prospective | – | 20 | 20 | – |
| Osser1992 | Retrospective | – | 186 | 164 | – |
| Yu2013 | Cross sectional | 2011–2012 | 147 | 175 | 35.6/33.6 |
| Zhang2013 | Retrospective | 2007–2010 | 737 | 775 | 29.6/29.9 |
| Zhang2015 | Retrospective | 2013–2014 | 704 | 372 | 29.9/30.4 |
| Dikshit1987 | Prospective | 1985–1986 | 219 | 288 | 26.7/26.5 |
| Kunzle2003 | Retrospective | 1991–1997 | 655 | 1131 | 32.3/33.2 |
| Total no of patients (n) | 5257 | 5566 |
Abbreviations: S smokers, NS non-smokers