Epidemiological characteristics and trends based on a joinpoint regression model of preterm birth with congenital heart disease in Changsha City, China, from 2011 to 2023.

Background: Preterm birth (PTB) and congenital heart disease (CHD) are major public health problems, and there are some associations in neonates between PTB and CHD. This study aimed to analyze the epidemiological characteristics and trends of PTB with CHD, including gender, residence, and maternal age.

Methods: This was an observational retrospective study of neonates with CHD born in Changsha City and discharged with a diagnosis of PTB from 2011 to 2023. The incidence and 95% confidence interval (CI) of PTB with CHD were calculated according to different gender, residence, and maternal age, respectively. Categorical data were shown as frequencies and percentages, and inter-group comparisons were conducted using the chi-square test. Joinpoint regression analysis of trends of PTB with CHD in total, different residence, and maternal age, respectively, was conducted.

Results: A total of 6,559 neonates with CHD were included. Of those, 1,039 were born preterm. The overall incidence of PTB with CHD was 15.84%. There was no statistically significant difference in the incidence of PTB with CHD between male and female infants (χ²=0.318, P=0.57). The incidence of PTB with CHD was higher in rural areas than it was in urban areas (χ²=27.92, P<0.001). The analysis showed significant differences in different maternal age groups (χ²=73.417, P<0.001). Overall, the incidence of PTB with CHD in Changsha City between 2011 and 2023 was on the rise in general, but without statistically significant difference in the trend [average annual percentage change (AAPC) =4.36%, P=0.09]. The incidence of PTB with CHD in urban areas of Changsha City increased from 2011 to 2023, and showed an obvious upward trend. The incidence of PTB with CHD in maternal age 30-34 years showed an obvious upward trend from 2011 to 2015 (APC =24.31, P=0.02), and showed a downward trend from 2015 to 2023 without statistically significant difference (APC =-3.62, P=0.20). Meanwhile, the incidence of PTB with CHD in maternal age ≥35 years showed an obvious upward trend from 2011 to 2016 (APC =25.49, P=0.04), and showed a downward trend from 2016 to 2023 without statistically significant difference (APC =-8.78, P=0.14).

Conclusions: Overall, the incidence of PTB with CHD in Changsha City from 2011 to 2023 was below the national average, and it showed an upward trend. Residence and maternal age were the determining factors for the incidence of PTB with CHD. There were obvious upward trends of the incidence of PTB with CHD in urban areas between 2011 and 2023, and in maternal age 30-34 years between 2011 and 2015, as well as in maternal age ≥35 years between 2011 and 2016.