Are pre- and early pregnancy lifestyle factors associated with the risk of preterm birth? A secondary cohort analysis of the cluster-randomised GeliS trial

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Preterm birth remains a global and partially unresolved health problem with affected newborns having an increased mortality and morbidity risk and often long-term health impairments. In this secondary analysis, researchers investigated the preventative role of modifiable risk factors for preterm birth and identified that a high dietary quality seems to be protective.

Since preterm birth is the leading cause of death in children under the age of five years, effective prevention strategies to reduce the risk of preterm birth are of paramount importance. Some factors seem to be generally acknowledged as triggers for preterm birth. However, results on whether or not several modifiable lifestyle factors contribute to the risk of preterm birth is still under discussion and little is known how they influence together with non-modifiable factors the overall risk profile. Therefore, this study aimed to simultaneously investigate associations between several pre- and early lifestyle factors as well as putative non-modifiable risk factors on the risk for preterm birth.

Researchers used data from the cluster-randomised controlled trial ‘Gesund leben in der Schwangerschaft’ (‘healthy living in pregnancy’) (GeliS) trial in which pregnant women received either a lifestyle intervention alongside routine care (intervention) or routine care only (control). As there was no difference in the preterm birth rate between both groups, data were pooled to one cohort. Included in this secondary analysis were all women with complete datasets. Multivariate logistic regression models were applied.

Clinical data were collected during prenatal examinations (maternity card) and via the birth records. Lifestyle data and data on maternal anxiety/distress or well-being were collected using validated questionnaires. Dietary quality was estimated by a healthy eating index (HEI) calculated per person.

Overall, 1738 women were included in the analysis. Significant associations were reported between nulliparity and advanced age of women (36–42 years) and the risk for preterm birth. While there was no significant evidence for an influence of psychological health/distress, smoking, lower education or low physical activity, as well as the type of activity on the risk of preterm birth, the dietary quality was found to play a major role. A low healthy eating index significantly increased the risk for preterm birth and the consumption of vegetables and energy from protein sources were shown to be protective.

The analysis provides valuable insights with validated data collected in a real-life setting. Limitations are a potential recall-bias related to questionnaire replies and that data are limited to Germany and not generally applicable to other populations. Further research on the mutual influence of modifiable and non-modifiable risk factors for preterm birth are urgently needed to develop efficient prevention strategies.

Paper available at: BMC Pregnancy and Childbirth

Full list of authors: Roxana Raab, Julia Hoffmann, Monika Spies, Kristina Geyer, Dorothy Meyer, Julia Günther, Hans Hauner