Objective  To investigate the relationship between parity and adverse pregnancy outcomes.

Methods  Keyword searches were conducted by 'parity', followed by random sampling to select 1200 patients: 400 from each of the first, second and third childbirths, designated as Groups 1, 2 and 3, respectively. A retrospective cohort study examined pregnancy outcomes across these three groups. Logistic regression was used to estimate the association between parity and pregnancy outcomes after adjusting for other confounding factors. We assessed the impact of parity on adverse pregnancy outcomes and the corresponding risk coefficients using receiver operating characteristic (ROC) curves and the area under the curve (AUC).

Results  Multiparity (parity ≥ 2) is a risk factor for preterm birth (odds ratio OR = 1.602, 95% CI: 1.181-2.173), perinatal anemia (OR = 1.468, 95% CI: 1.099-1.963), and uterine rupture (OR = 2.752, 95% CI: 1.261-6.007). It is a protective factor against low birth weight (OR = 0.564, 95% CI: 0.321-0.992), meconium-stained amniotic fluid (OR = 0.556, 95% CI: 0.418-0.739), and fetal distress (OR = 0.171, 95% CI: 0.080-0.365) (P < 0.05).

Conclusion  Increased parity is associated with a higher risk of certain adverse pregnancy outcomes, so it is important to be vigilant about the increased risk of specific complications, such as uterine rupture. Strictly controlling the indications for cesarean section and maintaining reasonable weight gain during pregnancy are effective measures to prevent adverse pregnancy outcomes in multiparous women.