The initial sample was 500 infants included in the study at birth. Among all preterm infants, 496 infants were followed-up in 1 month and 478 infants were followed-up in 2 months. Finally, 443 infants (88.6%) were followed-up until 6 months. The average exclusive breastfeeding duration was (3.69 ± 1.80) months, the longest one is 6.90 months. A flowchart with the recruitment and follow-up data appears in Fig 1 and Fig 2.
Participant demographics
In this study, 500 cases of puerperal and preterm infants were collected. The mothers were (30.41 ± 4.64) years old on average. 338 mothers had attended the undergraduate studies. More than 90% of women were employed during the pregnant period; 433 mothers live in the city. More than 40% of families got an income of more than 20000 RMB monthly,274 patients stayed in the hospital for more than 96 hours,393 puerperal had medical insurance; Additionally, more than 90% of women lived with their husbands during the perinatal period Among the mothers, 412 worked before delivery,411 women decided to continue working after the maternity leave, 85.6% women planned to conceive, 349 women expected to breastfeed for at least 6 to 12 months,300 women removed the breast milk by hands or pumped the breast, The results showed that 69.6% women pumped the breast less than 8 times per day, 60% women pumped the breast in 30 to 60 mins every time;273 mothers or their husbands visited the preterm infants during hospitalization, 47.8% women delivered the breast milk to their newborns in NICU.
The average age of husbands was (32.41 ± 1.36) years old, 279 husbands got the bachelor's degree;85.6% of husbands planned to get the babies; They hoped that the exclusive breastfeeding duration would maintain 6 to 12 months; 427 husbands' attitude towards breastfeeding reached 9–10 points.
256 infants were male and 36.8% weighted between 2000-2500g at birth; 308 preterm infants with a birth score of 9–10. More than 50% of preterm infants were fed formula in NICU(Table 1).
Table 1
Parental and preterm infants characteristics (n = 500)
Variable
|
Category
|
N
|
%
|
Maternal Age
|
18 ~ 25
|
35
|
7.0
|
|
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 ~ 10000
|
79
|
15.8
|
|
10001 ~ 15000
|
91
|
18.2
|
|
15001 ~ 20000
|
89
|
17.8
|
|
>20001
|
202
|
40.4
|
Type of delivery
|
Vaginal
|
221
|
44.2
|
|
Cesarean
|
279
|
55.8
|
Pregnancy duration (week)
|
28 ~ 32+ 6
|
43
|
8.6
|
|
33 ~ 34+ 6
|
49
|
9.8
|
|
35 ~ 36+ 6
|
408
|
81.6
|
Labor 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
|
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
|
Yes
|
428
|
85.6
|
|
No
|
72
|
14.4
|
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(years)
|
|
|
|
|
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.
|
298
|
59.6
|
|
No.
|
72
|
14.4
|
|
Full
|
130
|
26.0
|
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
|
About 19% of preterm infants were breastfed after 1-month discharge from the hospital, and the percentage dropped to 17% and 10% at 3 and 6 months after discharge, respectively. (Fig. 2).
Questionnaires survey
Table 2 displays maternal breastfeeding knowledge was (13.63 ± 2.93) at the hospital and decreased to (12.67 ± 3.72) in 6 months; maternal breastfeeding self-efficacy was (3.25 ± 0.77) at the hospital and increased to(3.34 ± 1.04) in 6 months; maternal postpartum depression was(16.63 ± 2.83) and decreased to (13.06 ± 1.86) in 6 months; maternal family support was( 2.94 ± 0.40) and increased to(3.06 ± 1.11) in 6 months. Through the ANOVA analysis, the following results were obtained: with the time changing, there was a significant difference between maternal breastfeeding self-efficacy and postpartum depression (P < 0.05); the longer the time was, the breastfeeding self-efficacy showed an upward trend, and the degree of postpartum depression decreased.
Table 2
Maternal Breastfeeding knowledge, Breastfeeding self-efficacy, Postpartum depression and Family support at birth,1,3,6 months
Factor
|
At hospital
(x̄ ± s)
|
1month
(x̄ ± s)
|
3months
(x̄ ± s)
|
6months
(x̄± s)
|
Within-group factors
|
F
|
P
|
Breastfeeding knowledge
|
13.63 ± 2.93
|
13.05 ± 3.68
|
12.37±4.37
|
12.67±3.72
|
2.403
|
0.108
|
Breastfeeding self-efficacy
|
3.25 ± 0.77
|
3.29 ± 1.04
|
3.34 ± 1.05
|
3.34 ± 1.04
|
55.228
|
<0.001
|
Postpartum depression
|
16.63 ± 2.83
|
13.28 ± 2.14
|
13.15 ± 2.01
|
13.06 ± 1.86
|
19.930
|
<0.001
|
Family support
|
2.94 ± 0.40
|
3.03±1.15
|
3.01±1.15
|
3.06±1.11
|
1.624
|
0.226
|
F:Fish statistic;P:P value |
Factors associated with exclusive breastfeeding duration
Table 3 shows the results from the Kaplan Meier curve. The maternal and family characteristics, breastfeeding knowledge, breastfeeding self-efficacy, postpartum depression, and family support were included in the Kaplan Meier method for univariate analysis. There were significant differences in exclusive breastfeeding duration among the levels of psychological preparation for pregnancy, delivering milk to the infants in NICU, the attitude of spouses towards breastfeeding, type of feeding in NICU, maternal breastfeeding knowledge, breastfeeding self-efficacy, maternal postpartum depression, and family support (P<0.05). The data were shown in Table 3 and Fig. 3.
Table 3 - Factors associated with exclusive breastfeeding duration: results obtained by Kaplan Meier curve
Variable
|
The type of breastfeeding outcome
|
Median.
|
95%CI
|
Kaplan-Meier
|
Delete .data
|
Breastfeeding(N)
|
N%.
|
(Month)
|
c2
|
P
|
Planned pregnancy
|
|
|
|
|
|
7.264
|
0.026
|
No
|
13
|
59
|
81.944
|
3.6
|
2.98-4.22
|
|
|
Yes
|
51
|
277
|
84.451
|
3.5
|
3.20-3.80
|
|
|
Sufficient
|
26
|
74
|
74
|
4.2
|
3.45-4.95
|
|
|
Deliver milk to the infants in NICU
|
|
|
|
|
|
15.346
|
<0.001
|
Yes
|
62
|
199
|
76.245
|
4.3
|
4.06-4.54
|
|
|
No
|
28
|
211
|
88.285
|
3.5
|
3.27-3.73
|
|
|
Husband's attitude towards breastfeeding.
|
|
|
|
|
|
16.649
|
0.005
|
5
|
2
|
5
|
71.429
|
4.3
|
2.25-6.35
|
|
|
6
|
1
|
10
|
90.909
|
2.0
|
0.00-4.05
|
|
|
7
|
0
|
1
|
100.000
|
0.8
|
—
|
|
|
8
|
9
|
45
|
83.333
|
3.5
|
2.87-4.13
|
|
|
9
|
4
|
27
|
87.097
|
3.8
|
3.18-4.42
|
|
|
10
|
74
|
322
|
81.313
|
3.6
|
3.33-3.87
|
|
|
Type of feeding in NICU
|
|
|
|
|
|
45.371
|
<0.001
|
Exclusive breastfeeding.
|
31
|
15
|
39.474
|
6
|
—
|
|
|
Mixed feeding.
|
23
|
189
|
89.231
|
3.5
|
3.25-3.75
|
|
|
Formula
|
36
|
206
|
82.772
|
3.7
|
3.29-3.92
|
|
|
Breastfeeding knowledge level (points)
|
|
|
|
|
|
82.015
|
<0.001
|
≥14
|
80
|
184
|
69.697
|
4.5
|
4.08-4.93
|
|
|
<14
|
10
|
226
|
95.763
|
2.8
|
2.47-3.13
|
|
|
Breastfeeding self-efficacy (points)
|
|
|
|
|
|
53.184
|
<0.001
|
≥44
|
66
|
135
|
67.164
|
4.4
|
3.94-4.86
|
|
|
<44
|
24
|
275
|
91.973
|
3.5
|
3.16-3.84
|
|
|
Postpartum depression (points)
|
|
|
|
|
|
53.221
|
<0.001
|
≥14
|
75
|
185
|
92.5
|
4.3
|
3.95-4.65
|
|
|
<14.
|
15
|
225
|
75
|
3.1
|
2.85-3.35
|
|
|
Family support (points)
|
|
|
|
|
|
86.196
|
<0.001
|
≥3.
|
83
|
175
|
67.829
|
4.4
|
3.95-4.85
|
|
|
<3 .
|
7
|
235
|
97.107
|
3.9
|
2.66-3.14
|
|
|
c2:Chi-square test ; P:p-Value ; CI: Confidence Interval
A significant single factor was included in cox regression, and the results showed that the more sufficient the degree of psychological preparation for planned pregnancy, the lower the risk of weaning and the longer the exclusive breastfeeding duration. In the multivariate analysis (95% confidence interval(CI) 0.531 ~ 0.873).Women who delivered milk to NICU during hospitalization had a lower risk of weaning than those who did not and breastfed the newborns longer( (CI) 1.412 ~ 2.288). Premature infants who were fed formula in NICU had a higher risk of weaning after discharge and were prone to stop breastfeeding ((CI 0.128 ~ 0.381). Women with higher levels of family support had a lower risk of weaning their preterm infants after discharge from the hospital and were more likely to keep breastfeeding ( (CI) 1.004 ~ 2.428). The data were shown in Table 4.
Table 4
factors associated with the risk of discontinuing exclusive breastfeeding which is the outcome event
Variable
|
Β
|
RR
|
95%CI
|
Se
|
z
|
P
|
Planned pregnancy
|
-0.385
|
0.681
|
0.531 ~ 0.873
|
0.127
|
9.166
|
0.002
|
Milk delivery during hospitalization
|
-0.586
|
0.797
|
1.412 ~ 2.288
|
0.123
|
22.706
|
<0.001
|
Artificial feeding of premature infants in NICU
|
1.509
|
1.221
|
0.128 ~ 0.381
|
0.278
|
29.512
|
<0.001
|
High Level of family support
|
-0.445
|
0.561
|
1.004 ~ 2.428
|
0.225
|
3.904
|
0.048
|
Β: Regression Coefficient; RR: risk ratio ;CI Confidence Interval ; Se standard error ; z:Wald Statistics P: p-Value |