Maternal correlates of spontaneous preterm birth in Kazakhstan: a matched case-control study

Abstract

Background: Preterm birth (PTB) continues to be a persistent health issue that significantly impacts neonatal morbidity and mortality worldwide. In Kazakhstan, the prevalence of preterm births is 7% making a substantial contribution to adverse health outcomes among infants. However, there is a lack of comprehensive research on the factors contributing to preterm birth in Kazakhstan. Aims: To study maternal factors associated with spontaneous PTB among Kazakh women. Methods: A case control study was conducted in three major reproductive hospitals in Atyrau, Aktobe and Kyzylorda from October 2022 to January 2023. The sample consisted of 90 cases with singleton live spontaneous PTB and 180 controls with spontaneous full-term delivery. Bivariate associations between categorical variables were assessed by chi-squared tests. Independent variables with p-values 0.1 in the bivariate analysis were entered into a conditional logistic regression model. Odds ratios (OR) with 95% confidence intervals (CI) were calculated. Results: Maternal education, periodontitis, body mass index and a history of PTB in previous pregnancies were associated with PTB in bivariate analysis. In multivariable models, only prior PTB (OR=38.1; 95% CI: 8.34–142) and periodontal disease (OR=2.09; 95% CI: 1.15–3.80) were associated with an increased risk of extremely and very preterm births while higher education (OR=0.44; 95% CI: 0.19–0.98) and a history of PTB (OR=27.2; 95% CI: 5.38–137) were associated with moderate to late PTB. Conclusion: Our results are in line with the international evidence on prior PTB being the most important determinant of PTB in the index pregnancy. Moreover, our findings on the associations with periodontal disease underline the importance of a targeted, individualized and interdisciplinary antenatal care to the reduction in the prevalence of PTB.