Figure 3
From: Preterm subtypes by immigrants’ length of residence in Norway: a population-based study
The estimated relative risks of spontaneous and non-spontaneous preterm delivery (PTD) in non-immigrants (reference line) and in immigrants by length of residence. The model adjusting for demographic factors included year of delivery, maternal age, parity and size of labor unit. The model adjusting for demographic and health factors included all demographic factors as well as gestational and pregestational diabetes, hypertensive disorder, smoking, small- and large-for-gestational age infant and major birth defects.