Abstract
Objective. To systematically review the risks of pregnancy outcomes among women of different parity. Material and methods. Electronic databases were searched for studies, in English language, in which primary objective was to assess association between parity and pregnancy outcomes. Meta-analyses were performed and unadjusted odds ratios (ORs) and mean differences along with 95% confidence interval (CI) were calculated. Main outcome measures. Low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), birth weight, and gestational age. Results. Forty-one studies, most with moderate risk of bias were included. Nulliparity was associated with increased unadjusted odds of LBW (OR 1.41, 95% CI 1.26, 1.58) and SGA (OR 1.89, 95% CI 1.82, 1.96) and reduction in birth weight (weighted mean difference −282 g, 95% CI −486, −79 g) but not PTB (OR 1.13, 95% CI 0.96, 1.34). Grand multiparity and great grand multiparity were not associated with LBW (OR 1.10, 95% CI 0.95, 1.32 and OR 0.92, 95% CI 0.78, 1.09) or PTB (OR 0.96, 95% CI 0.77, 1.19 and OR 1.32, 95% CI 0.61, 2.83). Conclusions. Nulliparity was associated with a significantly increased unadjusted risk of LBW/SGA birth, whereas grand multiparity and great grand multiparity were not associated with increased risk of pregnancy outcomes.
Acknowledgements
We sincerely thank Elizabeth Uleryk, Chief Librarian at the Hospital for Sick Children, Toronto, for her contribution in developing the search strategy and running searches on a periodic basis. She did not receive any compensation for this work.
This study was supported by funding from Canadian Institute of Health Research (CIHR) Knowledge Synthesis/Translation grant # KRS 86242. CIHR has no role in analyses, writing of the report, interpretation of data or decision to submit the manuscript.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.