Int J of Nursing Practice - 2017 - Maehara - Postpartum maternal function and parenting stress Comparison by feeding

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DO
I: 10.1111/ijn.12549
S U P P L EMEN T AR T I C L E
Postpartum maternal function and parenting stress:
Comparison by feeding methods
Kunie Maehara RN RM DNSc Research Associate Professor |
Emi Mori RN RM DMSc Professor | Hiroko Iwata RN RM PhD Research Associate Professor |
Akiko Sakajo RN RM DNSc Associate Professor | Kyoko Aoki RN RM MNSc Assistant Professor |
Akiko Morita RN RM MNSc Doctoral Candidate
Graduate School of Nursing, Chiba University,
Chiba, Japan
Correspondence
Dr Kunie Maehara, Graduate School of
Nursing, Chiba University, 1‐8‐1 Inohana,
Chuou‐ku, Chiba, Japan.
Email: kmaehara@faculty.chiba‐u.jp
Int J Nurs Pract. 2017;23(S1):e12549.
https://doi.org/10.1111/ijn.12549
Abstract
Aim: This cross‐sectional and longitudinal study explored primiparous mothers' functioning
and parenting stress on the basis of infant‐feeding method over the first 6 months postpartum.
Methods: Participants were Japanese primiparae who delivered live singleton infants
(N = 1120). Questionnaires, completed at 1, 2, 4, and 6 months postpartum, included demo-
graphics, feeding method, frequency of feedings, time required from infant's feeding to falling
asleep, mother's sleep time, Postnatal Accumulated Fatigue Scale, and the original Japanese ver-
sion of Parenting Stress Short‐Form Scale. Chi‐square tests and Welch F tests for one‐way anal-
ysis of variance were conducted.
Results: Exclusively breastfeeding mothers fed their infants more frequently, but required less
time from infant's feeding to falling asleep than either mixed or formula‐feeding mothers. Mixed
feeding mothers required more time for infant feeding and reported more severe fatigue and
greater parenting stress than breastfeeding mothers at 1 and 2 months postpartum. Exclusively
formula‐feeding mothers required more time to get their infant back to sleep and reported
greater parenting stress than the other groups at 6 months postpartum. Nearly 25% of mothers
continued breastfeeding exclusively through the first 6 months postpartum. Mothers often
changed feeding methods, with many exclusively breastfeeding by 6 months.
Conclusion: Feeding methods may affect maternal functioning and parenting stress across
the postpartum period.
KEYWORDS
breastfeeding, infant feeding methods, Japan, primiparous mothers, sleep
SUMMARY STATEMENT
What is already known about this topic?
• Although most first‐time Japanese mothers desire to exclusively
breastfeed, common beliefs suggest that formula supplementation
makes an infant sleep more, thereby increasing mothers' sleep. How-
ever, there are few studies examining the impact of feeding methods
(breastfeeding, mixed, and formula) on maternal daily functioning and
parenting stress during the first 6 months postpartum.
wileyonlinelibrary.com/jou
What this paper adds?
• This study adds to the knowledge base about the effects of feeding
methods on maternal functioning, sleep, and parenting stress across
the first 6 months postpartum.
The implications of this paper:
• The findings provide data‐based information for health profes-
sionals and for first‐time mothers regarding the promotion of exclu-
sive breastfeeding.
© 2017 John Wiley & Sons Australia, Ltdrnal/ijn 1 of 8
mailto:kmaehara@faculty.chiba-u.jp
https://doi.org/10.1111/ijn.12549
https://doi.org/10.1111/ijn.12549
http://wileyonlinelibrary.com/journal/ijn
2 of 8 MAEHARA ET AL.
1 | INTRODUCTION
Infant feeding has been a major area of concern for first‐time mothers,
especially during the first 6 months postpartum. According to a 2015
Japanese national nutrition survey of preschool children, the rate of
exclusive breastfeeding at 1 month postpartum was 51.3%, mixed
feeding 45.2%, and formula feeding 3.6% (Japan Ministry of Health
Labour and Welfare, 2007; Japan Ministry of Health Labour Welfare,
2016). This survey also indicated that mothers' concerns differed by
the feeding method used for their infants (Japan Ministry of Health
Labour Welfare, 2016).
Some studies have reported that breastfed infants wake more
often to eat than formula‐fed infants (Lee, 2000) and that
breastfeeding was strongly related to an increased demand for feed-
ings at night (Sievers, Oldigs, Santer, & Schaub, 2002). These behav-
iors are considered physiologically relevant for both breast milk
production and infants. The World Health Organization recommends
exclusively breastfeeding on demand, which is as often as the child
wants, through the day and night (World Health Organization,
1998). Infants need feedings based on their hunger cues; however,
mothers' lack of sleep can impair daily maternal functioning and
may lead to acute depression. In addition, first‐time mothers may
misinterpret infant's more frequent demand for feeding as an indica-
tion of insufficient breast milk production. Some investigators have
found a moderate association between parenting self‐efficacy and
perception of insufficient breast milk supply (McCarter‐Spaulding &
Kearney, 2001). Further, antenatal expectations of breastfeeding do
not always match mothers' postnatal reality (Wray, 2013). Conse-
quently, sleepless parents may act on the common assertion that for-
mula supplementation makes an infant sleep more and, in turn, helps
mothers obtain more sleep.
In contrast, some studies have reported no difference in maternal
sleep quality or duration by feeding method and that any type of infant
feeding interferes with maternal sleep (Gay, Lee, & Lee, 2004; Mont-
gomery‐Downs, Clawges, & Santy, 2010). Some investigators have
reported that mothers who exclusively breastfed slept more than
mothers who used formula at 1 and 3 months postpartum (Doan, Gar-
diner, Gay, & Lee, 2007; Doan, Gay, Kennedy, Newman, & Lee, 2014).
Others have compared breastfeeding mothers to mixed or formula‐
feeding mothers; the data showed that breastfeeding mothers had
more hours of sleep, better physical health, more energy, and lower
rates of depression (Kendall‐Tackett, Cong, & Hale, 2011). Among Jap-
anese mothers, exclusive breastfeeding was associated with greater
maternal confidence at 1 month postpartum among primiparous
mothers and greater enjoyment in childrearing at 3 months postpartum
(Maehara, Mori, Tsuchiya, Iwata, Sakajo, Ozawa, et al., 2016;
Yokoyama, Murai, Miyashita, Tatsumi, & Fujioka, 2012).
The World Health Organization recommendation for exclusive
breastfeeding until 6 months has been steadily adopted by more Japa-
nese mothers and health care professionals (World Health Organiza-
tion, 2003). Conversely, nursing practice places greater attention on
the needs of mothers who must create a balance between feeding rou-
tines, their sleep needs, and the other demands of motherhood
(Maehara, Mori, Tsuchiya, Iwata, Sakajo, & Tamakoshi, 2016). How-
ever, there is little research on whether there are differences in
maternal daily functioning and parenting during early infancy by infant
feeding choices (breastfeeding, mixed, or formula) among Japanese pri-
miparae. A better understanding of mothers' beliefs or perceived dis-
advantage of any feeding methods could help nurses provide
anticipatory guidance in choosing infant feeding type and the adapta-
tion to parenting during the first 6 months postpartum. The purpose
of this study was to examine primiparous mothers' daily functioning
(feeding routine, sleep, and fatigue) and parenting stress by infant‐
feeding method via a time‐series method over the first 6 months
postpartum.
2 | METHODS
A cross‐sectional and time‐series descriptive design was used. Data
were derived from a large multicenter prospective cohort study
(N = 2778) conducted in Japan to explore physical and psychosocial
well‐being of mothers of healthy infants during the first 6 months
postpartum (Iwata et al., 2016). In the present study, we examined data
collected at birth and at 1, 2, 4, and 6 months postpartum among only
the primiparous women (n = 1120) in the sample.
2.1 | Subjects and setting
Participants were recruited from 13 urban hospitals. Included in the
larger study were women who were 16 years of age or older, had a sin-
gleton live birth, and were able to communicate in Japanese. Mothers
or babies with serious health problems were excluded. Women who
had an infant that was born at <37 weeks gestation, weighed
<2500 g, or had any health issues resolved immediately after birth
were included if they were able to participate in rooming‐in during
their postpartum stay. The in‐hospital recruitment was conducted at
0 to 4 days postpartum by the researchers or research nurses at each
hospital using a brochure explaining the cohort study from May 2012
through September 2013. After recruitment, written consent forms
were obtained from women who agreed to participate in the cohort
study. Ethics approval for the full study was obtained from university
and hospital institutional review boards.
2.2 | Data collection
Participants were invited to complete self‐report questionnaires at 5 time
points: 1 day before discharge and 1, 2, 4, and 6 months postpartum.
Obstetrical data were extracted from medical records when the mothers
were discharged. The data included the following measures: demo-
graphics; infant‐feeding methods; maternal daily functioning (feeding rou-
tine, fatigue, and sleep); parenting stress; social support; maternal
confidence and satisfaction; physical symptoms; and depressive symp-
toms. Participants were given the questionnaires and returned them in a
sealed envelope to a collection box before hospital discharge. The ques-
tionnaires at 1, 2, 4, and 6 months postpartum were mailed ahead of
the assessment dates and included a stamped envelope with a preprinted
return address. The survey required about 15 to 30 minutes to complete.
Nonresponders were followed‐up via telephone 1 week after the mea-
surement date. If mothers were unable to be contacted or refused to
return the questionnaires, they were considered study dropouts.
MAEHARA ET AL. 3 of 8
Of the 3769 women enrolled in the main study, 2778 (73.7%
response rate) returned the questionnaires through 6 months postpar-
tum. Those who were delayed in returning the questionnaires, those
with incomplete data on the outcome scales, or those who had new
health problems detected by routine infant checkups at 1 month or 3
to 4 months after birth were excluded from the analyses, leaving a
sample size of 2075. Of these, we selected only data from the primip-
arous mothers (n = 1120) for the present study.
2.3 | Measures
Demographic variables included the following: maternal age, marital
status, education, financial readiness for childrearing, satisfaction with
social support, and mothers' feeding intentions at the infant's birth.
Obstetrical data included the following: type of delivery (C‐section or
vaginal delivery), infant gestation, infant birth weight, and related mea-
sures. The type of feeding method was categorized at each measure-
ment point as either (1) exclusive breastfeeding (BF)—breastfeeding
or breast milk feeding at all hours of the day; (2) mixed feeding (MF)
—any combination of breastfeeding and formula supplementation;
and (3) exclusive formula feeding (FF)—formula feeding at all hours of
the day.
Measures of maternal functioning included the following: mothers'
feeding routine, sleep, and fatigue at the 4 time points (1, 2, 4, and
6 months postpartum). Feeding routine was assessed by asking the
average frequency of feedings per day and mothers' estimate of the
average required times (minutes per feeding) from the start of infant
feeding to the infant falling asleep. Sleep was assessed by mothers'
self‐reported hours of nighttime sleep. The Postnatal Accumulated
Fatigue Scale (PAFS) was used to assess postpartum accumulated
fatigue (Tsuchiya et al., 2016). The PAFS has a 3‐factor structure (phys-
ical, emotional, and cognitive function), with 13 subjective fatigue
symptoms. Responses in the PAFS were measured on a 3‐point scale
(0 = rarely, 1 = sometimes, 3 = often) that yielded a range of possible
scores from 0 to 39 with higher scores indicating more severe fatigue.
In a previous study, the PAFS has shown acceptable convergent and
divergent validities and good internal consistency (Cronbach
α = 0.86) (Tsuchiya et al., 2016). In the present study, the Cronbach
α was 0.87 to 0.89 for the 4 time points.
Parenting stress was measured using the original Japanese version
of the Parenting Stress Short Form Scale (PSI‐SF) (19 items) at 2, 4, and
6 months postpartum. The original Japanese version of the PSI‐SF is
geared toward Japanese parents, which consists of 2 subscales: paren-
tal stress and child‐related stress (Araki et al., 2005; Kanematsu, 2016).
The parental stress subscale consists of 10 items (eg, “Since having a
child, I feel that I am almost never able to do things that I like to
do.”). The child‐related stress subscale includes 9 items (eg, “I feel that
my child is very moody and easily upset.”). Responses are measured on
a 5‐point Likert scale (1 = strongly disagree to 5 = strongly agree) with
higher scores indicating greater stress. This scale was validated and
demonstrated adequate internal consistency in a prior study of
mothers with healthy toddlers (Cronbach α = 0.84) (Kanematsu,
2016). The internal consistency in the present study ranged from
Cronbach α 0.78 to 0.84 for the 3 time points (2, 4, and 6 months post-
partum). Parenting stress was not assessed at 1 month postpartum,
because some items of PSI‐SF were considerable not to be suitable
among mothers with newborns.
2.4 | Data analysis
Participants were divided into 3 groups according to their current
feeding method (breast, mixed, and formula) at 1, 2, 4, and 6 months
postpartum. Because the size of each comparison group was different,
a Welch F test for one‐way analysis of variance with Tukey post hoc
test was used to examine differences among the 3 groups on the out-
come measures. An alpha level of .05 was used for all statistical tests.
Data were analyzed using SPSS for Windows version 23.0 (IBM Corp.,
Armonk, New York).
3 | RESULTS
Maternal demographic characteristics based on feeding methods at
1 month postpartum are presented in Table 1. The mean age of MF
mothers (32.8 ± 5.0 years) was significantly higher than BF mothers
(31.6 ± 4.3 years). Most mothers were married (98.7%), and more than
half (58.9%) reported being financially ready for childrearing. Most
(85.6%) mothers intended to exclusively breastfeed and BF mothers
were significantly more likely to have a higher education level, had a
vaginal delivery, and reported that they were very satisfied with instru-
mental support compared with MF or FF mothers.
The variation in the proportions of mothers' feeding methods at 1,
2, 4, and 6 months postpartum are shown in Table 2. The exclusive
breastfeeding rate was 47.9% at 1 month postpartum and increased
to 61.9% and 59.7% at 4 and 6 months, respectively. Mothers who
had continued breastfeeding exclusively from postpartum hospital stay
through the first 6 months postpartum were nearly 1 quarter of the
total sample (n = 272, 24.3%). Table 3 shows the means and standard
divisions of frequency of feedings per day, required times from the
start of infant feeding to falling asleep, mothers' length of nighttime
sleep, PAFS scores, parental stress PSI‐SF subscale scores, and child‐
related stress PSI‐SF subscale scores.
Feeding method affected the frequency of feedings per day at 1,
2, 4, and 6 months postpartum. Breastfeeding mothers fed more often
than either MF mothers or FF mothers. Moreover, MF mothers fed
more frequently than FF mothers at 1, 2, 4, and 6 months postpartum
(Figure 1). Feeding method also influenced the time required from the
start of infant feeding to falling asleep per feeding at 1, 2, 4, and
6 months postpartum. At 1 and 2 months, MF mothers required more
time from the start of infant feeding to
falling asleep than BF mothers.
At 4 and 6 months, BF mothers needed less time for feeding than
either MF or FF mothers. Conversely, FF mothers needed more time
from the start of infant feeding to falling asleep than either BF or MF
mothers at 6 months (Figure 2).
Regarding maternal sleep, at 2 months, MF mothers reported less
sleep at night than BF mothers. There were no differences among the
3 groups at 1, 4, and 6 months postpartum with respect to mothers'
length of nighttime sleep (Figure 3). At 1 and 2 months, MF mothers
had higher fatigue scores on the PAFS than BF mothers. At 4 and
6 months, there were no differences in the PAFS scores among the 3
TABLE 1 Sample demographics by feeding method reported at 1 month postpartum (N = 1120)
Feeding Method Statistical Test
Breast Mixed Formula
N, % n, % n, % n, % P Value
Age ‐ mean (SD)
32.2 (4.8) 31.6 (4.3) 32.8 (5.0) 30.3 (7.0) F = 8.98c .001
Marital status Single 14 (1.3) 7 (1.3) 7 (1.2) 0 (0) χ2 = 0.24d NS
Education College or higher 741 (66.2) 380 (70.8) 358 (63.5) 3 (16.7) χ2 = 26.6d <.001
Financially ready for childrearing (yes)
657 (58.9) 316 (59.0) 332 (59.1) 9 (50.0) χ2 = 0.60d NS
Delivery mode Vaginal 957 (85.4) 476 (88.6) 466 (82.5) 15 (83.3) χ2 = 8.47d .014
Caesarean section 163 (14.6) 61 (11.4) 99 (17.5) 3 (16.7)
Premature infant
18 (1.6) 5 (0.9) 13 (2.3) 0 (0) χ2 = 3.57d NS
Birth weight, g ‐ mean (SD)
3028.6 (346.3) 3030.8 (315.0) 3028.2 (372.2) 2972.4 (404.3) F = 0.18c NS
Very satisfied with supporta
702 (62.8) 369 (68.8) 323 (57.3) 10 (55.6) χ2 = 16.2d <.001
Feeding intentionsb
Breast 956 (85.6) 497 (92.6) 452 (80.3) 7 (41.2) χ2 = 113.6d <.001
Mixed 157 (14.1) 40 (7.4) 109 (19.4) 8 (47.1)
Formula 4 (0.4) 0 (0) 2 (0.4) 2 (11.8)
Abbreviation: NS, not significant.
Missing data: Marital status (n = 1), education (n = 1), financially ready for childrearing (n = 4), birth weight (n = 1), feeding intentions (n = 3), satisfaction with
support (n = 2).
aSatisfaction with instrumental support from families or others at 1 month postpartum.
bFeeding intentions at the infant's birth.
cWelch F test ANOVA (one‐way analysis of variance).
dχ2 test.
TABLE 2 Sample distribution by reported feeding method at 1, 2, 4,
and 6 months postpartum (N = 1120)
Postpartum
Month
Feeding Method
Breast Mixed Formula Missing
n, % n, % n, % n, %
1 537 (47.9) 565 (50.4) 18 (1.6) 0 (0)
2 613 (54.7) 465 (41.5) 39 (3.5) 3 (0.3)
4 693 (61.9) 344 (30.7) 82 (7.3) 1 (0.1)
6 669 (59.7) 326 (29.1) 123 (11.0) 2 (0.2)
4 of 8 MAEHARA ET AL.
groups (Figure 4). No differences emerged in the parental stress sub-
scale scores of PSI‐SF among the 3 groups at any postpartum month
(Figure 5). However, at 2 months, MF mothers had higher scores of
the child‐related stress subscale than BF mothers (Figure 6).
4 | DISCUSSION
The findings indicated that infant‐feeding methods influenced
mothers' feeding routines, sleep, fatigue, and parenting stress during
the first 6 months postpartum. There were some advantages and dis-
advantages associated with each feeding method for primiparous
mothers as they established their parenting lifestyle. First, BF mothers
were likely to feed more frequently than either MF or FF mothers,
which is congruent with prior literature (Lee, 2000; Sievers et al.,
2002). This seems logical as the protein in human milk is easily digested
and contains fewer calories during early lactation (Le Huerou‐Luron,
Blat, & Boudry, 2010; Lonnerdal, 2003). However, breastfeeding did
not have a negative impact on mothers' sleep, fatigue, and parenting
stress. This may be because BF infants required less feeding time than
either MF or FF infants. We might assume that the other mothers
required more alertness to prepare a bottle and to warm formula for
each nocturnal feeding.
Second, MF mothers required more time for infant feeding than
BF mothers during the first 6 months postpartum. The MF data show
a mean of 50 minutes (1 month) and 40 minutes (2 months) from the
start of infant feeding to falling asleep. This may explain why MF
mothers reported less nighttime sleep at 2 months and more severe
fatigue during the first 2 months postpartum than BF mothers. The
data show that approximately 80% of MF mothers at 1 month postpar-
tum intended to exclusively breastfeed. However, they may have per-
ceived their breast milk as insufficient. Infant crying after a feeding
may have been perceived as infant insatiety; thus, mothers may have
believed that they had an insufficient breast milk supply, which was
one of the main reasons mothers supplemented with formula (Balogun,
Dagvadorj, Anigo, Ota, & Sasaki, 2015). Presently in Japan, ready‐to‐
feed liquid formula is not available, only powdered formula. Mixed
powdered formula is limited as it requires time both to prepare and
FIGURE 1 Frequency of feedings per day compared by postpartum
month. Welch F test one‐way analysis of variance with Tukey post
hoc test. **P < .01,*P < .05
FIGURE 2 Infant feeding time compared by postpartum month.
Welch F test one‐way analysis of variance with Tukey post hoc test.
**P < .01
TABLE 3 Feeding routines, maternal functioning and parenting stress at 1, 2, 4 and 6 months (N = 1120)
Postpartum Month
1 2 4 6
Mean (SD) Mean (SD) Mean (SD) Mean (SD)
Feeding routines
Frequency of feedings per day (feedings/day) 10.1 (2.7) 8.9 (2.2) 7.6 (1.8) 7.2 (1.9)
Minutes per feeding from start of infant feeding to falling asleep 45.6 (20.7) 36.0 (18.4) 26.5 (16.3) 22.5 (14.7)
Maternal functioning
Length of nighttime sleep (hours/day) 5.0 (1.3) 5.7 (1.4) 6.5 (1.3) 6.4 (1.3)
Fatigue ‐ PAFS scores 9.4 (6.9) 6.9 (6.1) 6.3 (6.1) 6.5 (6.2)
Parenting stress—PSI‐SF
Parental stress scores N/A 20.0 (6.2) 19.4 (6.3) 19.8 (6.3)
Child‐related stress scores N/A 18.0 (5.4) 17.0 (5.3) 17.1 (5.2)
Abbreviations: PAFS, The Postnatal Accumulated Fatigue Scale; PSI‐SF: The original Japanese version of Parenting Stress Short Form Scale; N/A: not
applicable.
Missing data at 1, 2, 4, and 6 months (in order): Frequency of feedings per day (n = 5, n = 2, n = 2, n = 1), minutes per feeding from start of infant feeding to
falling asleep (n = 2, n = 3, n = 4, n = 2), length of nighttime sleep (n = 0, n = 0, n = 1, n = 0), PAFS scores (n = 0, n = 6, n = 1, n = 1).
FIGURE 3 Maternal hours of sleep per night compared by postpartum
month. Welch F test one‐way analysis of variance withTukey post hoc
test. *P < .05
FIGURE 4 Maternal fatigue compared by postpartum month. Welch F
test one‐way analysis of variance with Tukey post hoc test. **P < .01;
ns, not significant
MAEHARA ET AL. 5 of 8
FIGURE 5 Parental stress subscale scores compared at 2, 4, and
6 months postpartum. Welch F test one‐way analysis of variance
with Tukey post hoc test. ns, not significant
FIGURE 6 Child‐related stress subscale scores compared at 2, 4 and
6 months postpartum. Welch F test one‐way analysis of variance
with Tukey post hoc test. **P < .01; ns, not significant
6 of 8 MAEHARA ET AL.
to feed to an infant after breastfeeding. This result suggests that MF
mothers are faced with more difficulty in getting sufficient sleep during
the first 2 months postpartum as they have a greater burden managing
and providing feedings. Further, MF mothers had higher scores of the
child‐related stress subscale than BF mothers at 2 months postpartum;
this may imply that these infants had a difficult temperament. How-
ever, it remains unknown whether MF mothers used formula because
they experienced more difficulties in breastfeeding because their
infants were more easily upset, or if there were other factors underly-
ing their difficulty.
The exclusive breastfeeding rates were increased over the first
4 months postpartum (Table 2). This highlights an important finding
and goes against a common assumption that mothers will gradually
abandon breastfeeding. One reason is that more than 85% mothers
intended to exclusively breastfeeding. Moreover, “The Ten Steps to
Successful Breastfeeding” (World
Health Organization, 1998) was
disseminated to the nurses and midwives at the participating hospitals.
Thus, most mothers endorse breastfeeding on demand. Indeed, breast
milk production 6 months postpartum meets the demand for milk by
infants (Kent, Mitoulas, Cox, Owens, & Hartmann, 1999). The data also
showed that programs to promote exclusive breastfeeding would be
useful for mothers both early in the postpartum period and within
the first 6 months.
Notably, there were no significant differences between BF, MF,
and FF mothers in sleep times, fatigue, and parental stress after
4 months postpartum. This may be attributed to the fact that infant
night awakenings and night feedings decrease with infant age (Brown
& Harries, 2015; Sievers et al., 2002). Moreover, Mercer asserted that
new mothers establish a maternal identity around 4 months postpar-
tum (Mercer, 2004). Thus, anticipatory guidance can be offered to
new mothers and fathers that sleep loss, fatigue, and stress will decline
in a predicable manner, which should promote maternal adaptation.
Data also indicated that FF mothers fed their infants less fre-
quently but for longer intervals by 6 months postpartum.
Breastfeeding mothers were feeding more often but for shorter times.
However, FF mothers also reported that their infants were more likely
to take longer to settle and fall asleep at 6 months. While sucking,
especially sucking during breastfeeding, is an infant stress reducer
and sleep aid (Cubero, Valero, Sánchez, et al., 2005; Gray, Miller,
Philipp, & Blass, 2002); it also is a form of calming physical contact
for infants, which is not available for bottle‐fed infants (Aso & Iwatate,
2016).
4.1 | Study limitations
The changes in feeding times and frequency seen at 6 months postpar-
tum may have been because of maturation—a threat to internal valid-
ity. That is, normal changes in sleep cycles and feeding occur as an
infant develops. For example, solid foods are commonly introduced
at 6 months, even though infants may still want nighttime feedings
(Japan Ministry of Health Labour Welfare, 2016). Although formula
or solid foods may reduce the frequency of nighttime feeding, they will
not reduce the need for parents to attend to the infant at night (Brown
& Harries, 2015). Other investigators have suggested that
breastfeeding mothers frequently view the fragmented nature of
infant sleep as natural, while formula‐feeding mothers perceived this
as a problem to be fixed (Rudzik & Ball, 2016). Likewise, in the present
study, the FF mothers reported higher parental and child‐related stress
than either BF or MF mothers at 6 months. However, this comparison
was not statistically significant; that said, it does suggest that at
6 months, FF mothers may need to readjust their expectations and par-
enting style to accommodate changes in infant development and
personality.
Given the cross‐sectional design of this study, causation cannot be
inferred from the data. Plus, since this study focused on infant feeding,
the maturational threat to internal validity was present. Only 24.3% of
mothers had continued breastfeeding exclusively for the first 6 months;
however, others changed their feeding method. It is noteworthy that
many MF mothers reverted to BF over time. However, data were not
collected on the factors that may have influenced mothers' decisions
regarding feeding methods over the 6‐months period. It remains
MAEHARA ET AL. 7 of 8
unknown whether MF mothers used formula because they were
affected by sleep loss, or if they simply wanted their spouses to partic-
ipate in infant feeding, or if other family members were available to
assist in feeding.
Future research should include quantitative measures of daily
sleep, such as actigraphy and inquire about factors that influence pri-
miparous mothers' decision making about infant feeding. A better
understanding of mothers' decision making can help health care pro-
viders develop the best interventions or problem solving methods to
promote breastfeeding.
4.2 | Nursing implications
These findings have implications for nurses/midwives in the provision
of quality care considering maternal adjustment specific to feeding
method. Importantly, the findings presented herein provide evidence
that primiparous mothers may change feeding methods more than
once during the first 6 months postpartum and are likely to revert to
exclusive breastfeeding when they are able. Health care professionals
should promote breastfeeding to MF over FF because even a part‐time
nursing mother has the option to breastfeed exclusively in the future.
Thus, nursing care and anticipatory parental education must adapt to
the mother's choice for feeding their infant as well as to changes in
feeding status over time.
5 | CONCLUSION
The rate of exclusive breastfeeding in the present study was 47.9% at
1 month and 54.7% at 2 months postpartum, which are similar to the
national rates reported in Japan in 2015 (Japan Ministry of Health
Labour Welfare, 2016). Notably, maternal functioning and parenting
stress varied over the first 6 postpartum months by feeding method.
Mixed feeding mothers required more time for infant feeding and
reported severe fatigue and child‐related stress during the first
2 months. However, many MF mothers adopted exclusive
breastfeeding over time. Our findings suggest that organized programs
to support exclusive breastfeeding during the first 6 months postpar-
tum should be offered to both MF mothers and BF mothers. These
mothers can benefit from support for temporary formula use, perhaps
to share night feedings, especially during the first 2 months postpar-
tum. Likewise, all mothers would benefit from information on infant
nutrition, feeding patterns, sleep, and development regardless of feed-
ing method.
ACKNOWLEDGEMENTS
This study was supported by the Funding Program for Next Genera-
tion World‐Leading Research (No. LS022), Cabinet Office, Govern-
ment of Japan. The authors would like to thank the participants and
the nurses for their contribution to this study. We appreciate the
expertise of Tomoko Maekawa.
DISCLOSURE
The authors report no conflicts of interest.
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How to cite this article: Maehara K, Mori E, Iwata H, Sakajo A,
Aoki K, Morita A. Postpartum maternal function and parenting
stress: Comparison by feeding methods. Int J Nurs Pract.
2017;23(S1):e12549. https://doi.org/10.1111/ijn.12549
http://apps.who.int/iris/bitstream/10665/43633/1/9241591544_eng.pdf
http://apps.who.int/iris/bitstream/10665/43633/1/9241591544_eng.pdf
http://apps.who.int/iris/bitstream/10665/42590/1/9241562218.pdf
http://apps.who.int/iris/bitstream/10665/42590/1/9241562218.pdf
https://doi.org/10.1111/ijn.12549