Study designs of evaluations included in the review
Controlled studies were eligible for inclusion. The control groups in the included studies were age and parity matched, aged matched alone, or from provincial, hospital or national databases.
Specific interventions included in the review
Studies in which the majority of patients (equal to or greater than 85%) had conceived using IVF-EF or GIFT, compared with naturally conceived singletons or a national reference, were eligible for inclusion. The specific interventions assessed were IVF, IVF or GIFT, IVF or intracytoplasmic sperm injection (ICSI), or ICSI alone.
Participants included in the review
Studies that included patients who had a singleton birth conceived using IVF-ET or GIFT, compared with either naturally conceived singletons from a hospital database or a national reference, were eligible for inclusion.
Outcomes assessed in the review
Studies that reported the incidence of prematurity (clearly defined by the author) in comparison with a control were included. Studies that did not report data from single gestations separately from that of multiple gestations were excluded.
How were decisions on the relevance of primary studies made?
Two reviewers independently assessed studies for inclusion. This was undertaken blinded to the journal of publication and authors.