“…Several studies examined interbirth interval (rather than interpregnancy interval), [43][44][45][46][47][48][49][50][51][52][53] presented crude results only (no adjustment for maternal age), 22,43,49,52,54,55 or did not account for a potential non-linear relationship between interpregnancy interval and health outcome by either assuming that interpregnancy interval had a linear association with risks of adverse outcomes or using a reference category with no upper bound. 20,22,46,47,[56][57][58] Nevertheless, the conclusions of the excluded studies are consistent with our findings that short interpregnancy interval is associated with increased risk of uterine rupture among women with prior caesarean birth 46,47,49 and placental abruption, 17,52 as well as decreased risk of preeclampsia or other hypertensive disorders of pregnancy. 12,21,50,51,59,60 However, in contrast to the studies in our review, several excluded studies suggested that risks of obesity and gestational diabetes may actually increase with longer (not shorter) interpregnancy interval.…”