Pre-Pregnancy Health Status and Risk of Preterm Birth: A Large, Chinese, Rural, Population-Based Study

The aim of this study was to estimate the incidence of preterm birth (PTB) and identify maternal risk factors before pregnancy in rural China, and to determine their population-attributable fractions (PAFs). A prospectively population-based study was conducted in the city of Fuyang, China. Surveillance locations were randomly selected by cluster sampling based on administrative areas and geographic characteristics. Data were collected through interview questionnaires and medical examination records from the participants, then follow-up until discharge, fetus death, or at a maximum of 6 weeks postpartum, whichever came first. We used logistic regression analysis to identify the associated factors. PAFs were also estimated to examine the impact of risk factors. The incidence of PTB was 3.86% in this study. Multivariate analyses showed that risk factors for PTB were economic pressure (aOR=2.98, 95% CI, 2.40-3.71), hypertension (aOR=3.45, 95% CI, 2.23-5.36), hypoglycemia (aOR=2.07, 95% CI, 1.58, 2.72), hyperglycemia (aOR=1.69, 95% CI, 1.09, 2.62), serum creatinine (<44 μmol/L) (aOR=1.78, 95% CI, 1.13-2.40), hypothyroidism (aOR=1.37, 95% CI, 1.06-1.78), positivity for anti-CMV IgM (aOR=2.57, 95% CI, 1.21-5.45), multiple pregnancy (aOR=3.35, 95% CI, 1.87-6.00), and parity (≥3 times) (aOR=1.67, 95% CI, 1.05-2.64). Economic pressure was the most significant contributor (11.57%), while parity was the lowest (0.10%). This study demonstrated the relatively high burden of PTBs in a rural Chinese area. A broader focus on the risk factors prior to pregnancy amenable to interventions of women may reduce the incidence of PTB.