Table 1.

Parental and preterm infants characteristics (n = 500)

Variable	Category	N	%
Maternal Age	18 ~ 25	35	7.0
(mean = 30.41)	26 ~ 30	172	34.4
	31 ~ 34	243	48.6
	≥35	50	10.0
Maternal educational level	Primary studies	15	3.0
	Secondary studies	49	9.8
	Undergraduate studies	338	67.6
	Postgraduate studies	98	19.6
Maternal occupation	Working	494	98.8
	Unemployed	6	1.2
Residency	City	433	86.6
	Countryside	67	13.4
Family income (RMB)	≤5000	39	7.8
	5001 ~ 10,000	79	15.8
	10,001 ~ 15,000	91	18.2
	15,001 ~ 20,000	89	17.8
	20,001 ~ 25,000	126	25.2
	25,001 ~ 30,000	36	7.2
	30,001 ~ 35,000	28	5.6
	≥35,001	12	2.4
Mode of delivery	Vaginal	221	44.2
	Cesarean	279	55.8
Gestational week	28 ~ 32+ 6	43	8.6
	33 ~ 34+ 6	49	9.8
	35 ~ 36+ 6	408	81.6
Labour Complication	Yes	252	50.4
	No	248	49.6
Payment type of expenses	Medical insurance	393	78.6
	Self-paid	92	18.4
	Other	9	1.8
	Unclear	6	1.2
Live with husbands during Perinatal period	Yes	487	97.4
	No	13	2.6
Prenatal work	Yes	412	82.4
	No	88	17.6
Length of hospital stay (hour)	36 ~ 48	26	5.2
	49 ~ 72	102	20.4
	73 ~ 96	98	19.6
	≥97	274	54.8
Plan to work after maternity leave	Yes	411	82.2
	No	89	17.8
Planned pregnancy	Prepared	328	65.6
	unprepared	72	14.4
	fully prepared	100	20.0
Estimated breastfeeding time (month)	<6	100	20.0
	6 ~ 12	349	69.8
	12 ~ 24	49	9.8
	>24	2	0.4
Methods of removing breast milk during the period of mother and infant seperation	By hand	63	12.6
	Breast pump	137	27.4
	By hand+ Breast pump	300	60.0
Number of removing the milk by hand per day	<8	348	69.6
	8 ~ 12	149	29.8
	>12	3	0.6
Time of each removing the milk by hand	<30	158	31.6
	30 ~ 60	300	60.0
	>60	42	8.4
Visit NICU newborns	Yes	273	54.6
	No	227	45.4
Deliver milk to the infants in NICU	Yes	239	47.8
	No	261	52.2
Husband Age (mean = 32.95)	18 ~ 25	15	3.0
	26 ~ 30	150	30.0
	31 ~ 34	195	39.0
	≥35	140	28.0
Husband’s education. Level	Primary studies	13	2.6
	Secondary studies	67	13.4
	Undergraduate degree	279	55.8
	Postgraduate studies	141	28.2
Planned pregnancy	Yes.	428	85.6
	No.	72	14.4
Husband’s attitude towards breastfeeding.	5	7	1.4
	6	11	2.2
	7	1	0.2
	8	54	10.8
	9	31	6.2
	10	396	79.2
Infant gender	Male	256	51.2
	Female	244	48.8
Weight at birth(g)	<1500	28	5.6
	1500 ~ 2000	42	8.4
	2001 ~ 2500	128	25.6
	2501 ~ 3000	184	36.8
	≥3001	118	23.6
Apgar score	≤6	13	2.6
	7 ~ 8	179	35.8
	9 ~ 10	308	61.6
Type of feeding in NICU	Exclusive breastfeeding	38	7.6
	Partial breastfeeding	195	39.0
	Formula	267	53.4