Risk factors for preterm labor: An Umbrella Review of meta-analyses of observational studies

Abstract

Preterm birth defined as delivery before 37 gestational weeks, is a leading cause of neonatal and infant morbidity and mortality. Understanding its multifactorial nature may improve prediction, prevention and the clinical management. We performed an umbrella review to summarize the evidence from meta-analyses of observational studies on risks factors associated with PTB, evaluate whether there are indications of biases in this literature and identify which of the previously reported associations are supported by robust evidence. We included 1511 primary studies providing data on 170 associations, covering a wide range of comorbid diseases, obstetric and medical history, drugs, exposure to environmental agents, infections and vaccines. Only seven risk factors provided robust evidence. The results from synthesis of observational studies suggests that sleep quality and mental health, risk factors with robust evidence should be routinely screened in clinical practice, should be tested in large randomized trial. Identification of risk factors with robust evidence will promote the development and training of prediction models that could improve public health, in a way that offers new perspectives in health professionals.

Strategies for Safeguarding High-Risk Pregnancies From Preterm Birth: A Narrative Review

“…It is important to know what the risk factors are that are associated with preterm birth; thus, we can predict women at risk and manage the cases properly to avoid the consequences of preterm birth. In an umbrella review [11] of 1511 primary studies discussing 170 associations, only seven of those associations had a robust association with preterm birth. This study argues with the WHO guidelines [12] of waiting for at least six months to conceive after a miscarriage; this is supported by excluding a large cohort study.…”

“…Some risk factors showed a high suggestion of association with preterm labor; some were racial like black or African and aboriginal ethnicity, some were social as unmarried women and women who are subjected to intimate partner violence, women with severe morbidity as hemorrhagic and hepatic disorders, chronic kidney disease, bleeding in the first trimester, placenta previa, velamentous cord insertion, obstetric cholestasis, obesity (BMI >40 kg/m 2 ), underweight women, maternal age equal or more than 45 years, prior surgical termination of pregnancy, history of cancer, and cervical intraepithelial neoplasia treatment [11].…”