Trends and factors associated with changes in preterm birth at KCMC referral hospital in Northern Tanzania. A birth registry- based study

Background Preterm birth is a public health concern. It is a leading cause of neonatal mortality and the second leading cause of under-five mortality globally. Despite the current efforts in addressing causes and risk of preterm birth, the burden remains unacceptably high, especially in developing countries. Furthermore, while the risk factors for preterm birth are widely known, it is unclear how these factors change over time and how they influence changes in proportions of preterm birth. Methods This was a secondary data analysis using maternally linked data from the Kilimanjaro Christian Medical Center Medical birth registry from 2000 to 2018 and included all recorded deliveries. Data were cleaned and analyzed using STATA software version 15. The trends of preterm birth proportions were computed using Joinpoint regression model. The multivariable Poisson decomposition model was used to determine factors associated with changes in proportions of preterm birth. Results The proportions of preterm birth increased significantly from 11.5% in 2000 to 21.2% in 2018, with the annual percentage change of 5%. Change in proportions of antenatal care visits significantly contributed to 82%, 24% and 53% of changes in proportions of preterm birth respectively in all three phases while other factors such as multiple pregnancies, preeclampsia, use of alcohol during pregnancy and young maternal age (≤ 19 years) each contributed to less than 10% of the change in proportions of preterm birth. Conclusion The trend in the proportions of preterm birth has gradually increased in Northern Tanzania. Factors that contributed to the change in proportions of preterm birth are changing with time. ANC visits reported to be the main contributors for changes in PTB proportions across the study period. Therefore coordinated efforts are needed to promote early initiation, adequacy of ANC visits among women for early identification and management of high-risk pregnancies.