Fig. 2
From: The association between parity and spontaneous preterm birth: a population based study
Odds ratio’s for spontaneous preterm birth (a) < 37 weeks, (b) < 32 weeks, (c) < 28 weeks and between (d) 34–37 weeks of gestation per parity. Abbreviations: OR, odds ratio. *Correction model A: adjusted for maternal age (< 20 years, ≥40 years and continuous), non-White ethnicity, low socioeconomic status, and a prior preterm birth. Correction model B: adjusted for A and artificial reproductive techniques, male fetal gender, hypertension, and small for gestational age < p10