European Journal of Obstetrics & Gynecology and Reproductive Biology
ReviewPreterm birth and low birth weight among in vitro fertilization singletons: A systematic review and meta-analyses
Introduction
In vitro fertilization (IVF) provides an opportunity for an increasing proportion of couples who were unable to conceive spontaneously to become parents. Following the first successful IVF birth in 1978, the proportion of infants born as a result of this procedure has steadily increased to approximately 1 in 30 in Finland [1] and 1 in 80 in the USA [2].
The last meta-analysis (with the literature search ending in 2003) was published by our group and identified that singletons born after IVF had increased perinatal risks compared to spontaneously conceived singletons after accounting for maternal age [3]. However, there have been a number of studies published since that time, and a current, unbiased, systematic review of the literature is required. Our previous study reported only pooled crude data, whereas we now wanted to also examine data which accounted for confounders. We have focused on singletons given that they make up the largest proportion of IVF infants. This review will concentrate on the two most important determinants of neonatal morbidity and mortality, namely preterm birth (PTB) and low birth weight (LBW) births [4].
Section snippets
Materials and methods
We followed the MOOSE consensus statement on the conduct of meta-analysis of observational studies [5].
Results
Three hundred and sixty-one non-duplicate titles and abstracts were identified, 117 full articles were reviewed and 17 articles met inclusion criteria [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24] with 31,032 singletons conceived through IVF and IVF/ICSI and 81,119 spontaneously conceived singletons (Fig. 1). Although many studies were labeled as case–control studies and others as retrospective cohort studies, all 17 studies involved
Comment
In this systematic review and meta-analyses, we determined that IVF singletons have higher rates of our primary outcomes, PTB and LBW, the two most important determinants of neonatal morbidity and mortality [4]. In addition, IVF singletons have increased risks of moderate and late PTB, VLBW, IUGR, lower mean birth weights and shorter mean gestations. The risks of the most extreme preterm birth cannot be assessed due to the inclusion criteria of the original studies. Two studies included births
Acknowledgement
We thank Elizabeth Uleryk, Chief Librarian, Hospital for Sick Children, Toronto, for developing the search strategy.
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See Appendix C.