Beyond birth spacing: interpregnancy interval and correlates of non-severe maternal morbidity among Chinese multiparous women

Non-severe maternal morbidity represents a substantial component of perinatal health trajectories. Although interpregnancy interval (IPI) has been examined in relation to reproductive health outcomes, the social and behavioral factors associated with non-severe maternal morbidity among multiparous women remain underexplored. A clear understanding of these factors could inform targeted interventions to improve maternal health. To examine the association between IPI and four domains of non-severe maternal morbidity—physical symptoms, anxiety, depression, and functional impairment—among Chinese multiparous women, and to identify maternal, psychosocial, and obstetric correlates of these outcomes. A cross-sectional study was conducted at a tertiary women’s hospital in Shanghai, China. A total of 449 participants in late pregnancy were recruited. IPI was the primary exposure and was categorized as < 2 years, 2-<5 years, and ≥ 5 years. The four primary outcomes, including physical symptom burden, clinically significant anxiety, clinically significant depression, and functional impairment, were analyzed separately. Primary analyses examined associations between IPI and each outcome using multivariable regression models. Exploratory secondary analyses examined maternal, psychosocial, and obstetric correlates of the four outcomes. Comparisons of individual physical symptoms across IPI categories were also exploratory. The mean IPI was 5.87 (SD 3.67) years. In primary analyses, IPI was not significantly associated with physical symptom burden, clinically significant anxiety, clinically significant depression, or functional impairment after multivariable adjustment (all P > 0.05). In exploratory secondary analyses, underweight women had higher odds of clinically significant anxiety than women with normal BMI (aOR = 3.186, 95% CI: 1.139–8.907), whereas absence of domestic violence exposure was associated with lower odds of clinically significant depression (aOR = 0.275, 95% CI: 0.123–0.617). Unintended pregnancy was associated with higher functional impairment (aMR = 1.069, 95% CI: 1.011–1.131), whereas absence of pregnancy complications (aMR = 0.937, 95% CI: 0.886–0.991) and absence of domestic violence exposure (aMR = 0.867, 95% CI: 0.790–0.951) were associated with lower functional impairment. In exploratory analyses, pelvic pain (χ² pelvic pain = 11.986, P = 0.002) and edema of the hands and feet (χ² edema = 6.977, P = 0.031) showed nominal differences across IPI categories, whereas most other physical symptoms did not differ significantly. IPI was not significantly associated with physical symptom burden, clinically significant anxiety and depression, or functional impairment among Chinese multiparous women. Exploratory secondary analyses identified associations of selected maternal, psychosocial, and obstetric factors, particularly prepregnancy BMI, domestic violence exposure, unintended pregnancy, and pregnancy complications, with specific dimensions of non-severe maternal morbidity. These hypothesis-generating findings require longitudinal confirmation and do not support clinical recommendations at this stage.