Table 4.

The Firth logistic regression performed for multivariate analysis including preterm labor (n = 331)

	Coefficients	OR (95% CI)	P value
Age at delivery, y	0.02	1.02 [0.93, 1.12]	0.669
Delivery week	−0.11	0.90 [0.63, 1.24]	0.538
Infant weight, kg	−0.81	0.45 [0.13, 1.51]	0.197
Duration of breastfeeding  <6 months  6–12 months  >12 months	Reference 1.50 1.90	Reference 4.46 [1.24, 16.48] 6.66 [2.11, 20.18]	0.022 0.002
Preterm labor (yes/no)	2.27	9.65 [1.25, 1243.65]	0.025

CI, confidence interval; OR, odds ratio.