Induced termination of pregnancy and low birthweight and preterm birth: a systematic review and meta-analyses.

BACKGROUND: History of induced termination of pregnancy (I-TOP) is suggested as a precursor for infant being born low birthweight (LBW), preterm (PT) or small for gestational age (SGA). Infection, mechanical trauma to the cervix leading to cervical incompetence and scarred tissue following curettage are suspected mechanisms.

OBJECTIVE: To systematically review the risk of an infant being born LBW/PT/SGA among women with history of I-TOP.

SEARCH STRATEGY: Medline, Embase, CINAHL and bibliographies of identified articles were searched for English language studies.

SELECTION CRITERIA: Studies reporting birth outcomes to mothers with or without history of induced abortion were included.

DATA COLLECTION: and analyses Two reviewers independently collected data and assessed the quality of the studies for biases in sample selection, exposure assessment, confounder adjustment, analytical, outcome assessments and attrition. Meta-analyses were performed using random effect model and odds ratio (OR), weighted mean difference and 95% confidence interval (CI) were calculated.

MAIN RESULTS: Thirty-seven studies of low-moderate risk of bias were included. A history of one I-TOP was associated with increased unadjusted odds of LBW (OR 1.35, 95% CI 1.20-1.52) and PT (OR 1.36, 95% CI 1.24-1.50), but not SGA (OR 0.87, 95% CI 0.69-1.09). A history of more than one I-TOP was associated with LBW (OR 1.72, 95% CI 1.45-2.04) and PT (OR 1.93, 95% CI 1.28-2.71). Meta-analyses of adjusted risk estimates confirmed these findings.

CONCLUSIONS: A previous I-TOP is associated with a significantly increased risk of LBW and PT but not SGA. The risk increased as the number of I-TOP increased.