Table 6.  Logistic regression analysis of factors associated with delay in resumption of postpartum menstruation.

Variables	Odds ratio	95% CI	P
Age at delivery (years)	1.122	1.043–1.207	< 0.01**
Past history of irregular menstruation		1.349–6.349	< 0.01**
No (reference)	1.000
Yes	2.927
Infertility treatment		0.688–6.470	0.19
No (reference)	1.000
Yes	2.110
History of taking oral contraceptives		1.062–5.204	0.04*
No (reference)	1.000
Yes	2.351
Breastfeeding at 18 months after delivery		5.394–19.845	< 0.01**
No (reference)	1.000
Yes	10.346
Level of satisfaction with the husband’s participation in childcare		1.031–4.064	0.04*
Satisfaction (reference)	1.000
Dissatisfaction	2.047

Cases used in the analysis: n = 685, cases excluded due to missing data: n = 77. *P < 0.05, **P < 0.01. CI, confidence interval.