“…Forty‐one studies were included in this review and their baseline characteristics are described in Table 1 (9–49). Thirty‐five studies were excluded: 15 studies reported no neonatal outcome (3, 50–63), seven studies had no comparator group (64–70), four studies reported only on a very specific population (71–76), three were reviews or editorials (2, 77, 78), one study compared two socioeconomic groups (79), one study reported longitudinal data with multiple observations (80), and one was an outcome based study rather than exposure based study (81).…”