Predictors of Breastfeeding and Breastmilk Feeding Among Very Low Birth Weight Infants

Abstract

Objective:

This study investigated associations between maternal and infant factors and breastfeeding practices in infants born <30 weeks gestation in the neonatal intensive care unit (NICU).

Study Design:

This study was a retrospective cohort. Mother and infant characteristics were investigated for associations with breastfeeding outcomes using multivariate logistic regression.

Results:

Seventy-eight percent of infants initiated breastmilk feedings, 48% of those continued to have breastmilk at discharge, and 52% were breastfed in the hospital. The average duration of breastmilk feedings was 43 days. Mothers who were married and had a multiple-infant birth were more likely to initiate breastmilk feeds, African American mothers and younger mothers had less success with maintaining breastmilk feeds until hospital discharge, and African American mothers and mothers of lower socioeconomic status were less likely to participate in direct breastfeeding in the NICU.

Conclusions:

Infant factors, such as birth weight and gestational age, were not associated with breastfeeding behaviors. Mothers can succeed with breastfeeding the premature infant. By understanding what maternal groups are at risk for breastfeeding failure, targeted interventions in the NICU can be implemented.

Introduction

The American Academy of Pediatrics recommends exclusive breastfeeding for the first 6 months with breastfeeding and supplemental solids until infants are 1 year old.¹ Breastfeeding recommendations are made because of the significant benefits associated with breastfeeding. These include decreased risk of infection, otitis media, diarrhea, asthma, allergies, and sudden infant death.^2–7 In addition, healthcare costs and mortality are diminished among breastfed children.^2,8

Breastmilk is perhaps of greater importance in premature infants, because it decreases the risk of multiple medical problems, which can further complicate the medical course and put them at a higher risk for later neurodevelopmental consequences. The benefits of human milk feedings for premature infants include decreased rates of retinopathy of prematurity, necrotizing enterocolitis, sepsis, and respiratory illness, with resultant shorter duration of hospitalization.^4,9 In addition, breastmilk has developmental benefits for premature infants. Premature infants who are breastfed have demonstrated improved motor outcomes, better neurobehavioral organization and cognitive skills, and decreased utilization of healthcare services later in life.^10–12 However, perinatal medical condition is an important predictor of successful breastfeeding,^13,14 with being admitted to the neonatal intensive care unit (NICU) being one of the strongest predictors of not being exclusively breastfed at discharge.¹⁵

Infants hospitalized in the NICU have their own set of challenges associated with breastfeeding, and mothers must express breastmilk for gastric feeds until the infant is neurologically mature and medically stable enough to engage in direct breastfeeding.¹⁶ Therefore, mothers of infants born very low birth weight (VLBW) must overcome significant barriers to succeed with breastfeeding until the infant is discharged home.

Studies on predictive factors of breastfeeding in premature infants have conflicting results. Some studies have found that higher gestational age and higher birth weight are associated with higher rates of breastfeeding,^13,14 while others have found that mothers of premature infants recognize the unique medical needs of the infant¹⁷ and that, consequently, breastmilk feeding initiation rates are higher among low birth weight infants. More maternal education, private insurance, breastfeeding experience, and Caucasian race¹⁷ have been shown to be associated with breastmilk feeding initiation, whereas multiple-infant pregnancy, VLBW, and increased maternal age are all associated with longer breastmilk feedings.¹⁸

Although many studies fail to differentiate between breastmilk feeding and breastfeeding, these two factors should be investigated separately as they represent different levels of success, based on the perception of the mother. Mother–infant dyads who make the transition to breastfeeding are more often older, with private insurance, with breastfeeding experience, and with a shorter length of stay.¹⁹ Decreased length of stay and higher gestational age are associated with higher probability of having breastmilk until discharge.^17,19,20 To date there have been no studies that have investigated factors associated with breastmilk feeding initiation, breastfeeding at discharge, duration of breastfeeding, direct breastfeeding, whether the first feeding was at the breast, and the gestational age at the first breastfeeding in VLBW infants.

By understanding what factors are associated with breastfeeding practices in VLBW infants, better interventions can be developed to enable mothers to successfully breastfeed high-risk infants until discharge and beyond. The purpose of this study was to investigate associations between maternal and infant factors and breastfeeding practices in VLBW infants hospitalized in the NICU.

Subjects and Methods

This observational study used data obtained from a previous study investigating the effect of an educational intervention on breastfeeding practices in the NICU.²¹ Participants in the study were 135 VLBW infants (<1,500 g at birth), hospitalized in a level II or III nursery for greater than 7 days over two separate 9-month periods and who had no medical or developmental complications that contraindicated breastfeeding. Data collection was performed via retrospective chart review.

Sociodemographic factors were collected for each infant's mother, including maternal age, race, socioeconomic status, and marital status. Socioeconomic status was defined, from the medical chart, as the infant's eligibility for Medicaid. Those qualifying for Medicaid were classified as being low socioeconomic status, and those not eligible for Medicaid were classified as having high socioeconomic status. Infant factors were collected including gestational age at birth, birth weight, sex of the infant, number of siblings, length of stay, and whether it was a single or multiple-infant birth.

Breastfeeding outcome variables were collected, including breastmilk feeding initiation, breastmilk at discharge, and direct breastfeeding in the NICU. In addition, gestational age at the first direct breastfeeding and whether the first oral feeding was at the breast were tracked for each infant. Breastmilk feeding initiation was defined as whether the infant ever received breastmilk by breastfeeding, bottle feeding, or gastric tube. Breastfeeding was defined as the number of times that the infant was directly put to the breast during the hospitalization. Breastfeeding at discharge was defined as whether any breastmilk was given (by bottle or breast) in the 24 hours prior to discharge. The first oral feeding was a variable indicating whether the first oral feeding was at the breast (yes) or if the first oral feeding was via bottle, cup, or syringe (no). The gestational age at the first breastfeeding attempt was the number of completed postmenstrual weeks at the time of the first breastfeeding attempt.

Exploratory analyses were conducted using Wilcoxon Sum Rank tests, Cochran-Mantel-Haenszel statistics, and univariate analysis of variance. All variables that achieved significance were then put into a multivariate logistic regression model to determine which factors are predictive of the outcome variables, while holding all other factors fixed.

Results

The mean gestational age of the sample was 28.6 (±2.5) weeks, with a birth weight of 1,091 (±256) grams, an average maternal age of 27 (±6.8) years, and an average length of stay of 51.4 (±30.9) days. Eighty percent were single pregnancies, 75% were low socioeconomic status, 50% were the first child, 55% of infants were female, and 49% were African American.

The breastmilk initiation rate was 78%. Among those who initiated breastmilk feedings, 48% continued to provide breastmilk at discharge, while 34% provided exclusive breastmilk at discharge. Among those who initiated breastmilk feedings, the duration of breastmilk feedings ranged from 1 to 109 days, and the mean duration of breastmilk feeding was 43 days. Of those who initiated breastmilk feedings, only 52% directly breastfed their infants while in the NICU. The range for number of times breastfed in the NICU was 0–57, and the mean number of times breastfed in the hospital was 6.75 ± 12.2. Eighteen percent of mothers performed the first oral feeding at the breast. The average gestational age at the first breastfeed was 33 weeks of gestation with a range of 30–37 weeks.

Associations were found between breastmilk feeding initiation rates and socioeconomic status (p = 0.01), marital status (p = 0.00), first child (p = 0.01), and length of stay (p = 0.03). However, when these factors were put into a multivariate model to determine the effect of a factor while holding all others constant (Tables 1 and 2), only multiple-infant pregnancy (p < 0.01) and marital status (p < 0.01) had significant effects on breastmilk feeding initiation. The odds ratio for multiple-infant pregnancy was 4.4, and the odds ratio for married marital status was 7.7.

Table 1.

Categorical Variable Characteristics of Very Low Birth Weight Infants and Breastmilk Feeding Initiation, Breastfeeding, and Breastmilk Feeds at Discharge

	Were breastmilk feeds initiated?			Did the mother breastfeed the infant while in the NICU?			Did the mother continue to provide breastmilk feedings until DC?
Categorical variable	Yes	No	P value for univariate analysis/multivariate/OR	Yes	No	P value for univariate analysis/multivariate/OR	Yes	No	P value for univariate analysis/multivariate/OR
SES
Medicaid eligible	72%	28%	0.01	37%	63%	< 0.01/< 0.01/15	23%	77%	0.01
Not Medicaid eligible	94%	6%	0.01	90%	10%	< 0.01/< 0.01/15	58%	42%	0.01
Race
African American	72%	28%	0.17	33%	67%	0.01/0.01/6.9	13%	87%	< 0.01/< 0.01/7.6
Non–African American	82%	18%	0.17	68%	32%	0.01/0.01/6.9	50%	50%	< 0.01/< 0.01/7.6
Number of infants
Singleton	78%	22%	< 0.01/< 0.01/4.4	48%	52%	0.32	29%	71%	0.29
Twins/triplets	100%	0%	< 0.01/< 0.01/4.4	63%	37%	0.32	43%	57%	0.29
Marital status
Unmarried	91%	9%	< 0.01/< 0.01/7.7	37%	63%	0.02	45%	55%	0.04
Married	67%	33%	< 0.01/< 0.01/7.7	67%	33%	0.02	20%	80%	0.04
Sex of baby
Female	81%	19%	0.39	60%	40%	0.14	43%	57%	0.06
Male	75%	25%	0.39	41%	59%	0.14	21%	79%	0.06
Birth order
First child	88%	12%	0.01	57%	43%	0.41	23%	77%	0.15
Has siblings	68%	32%	0.01	46%	54%	0.41	40%	60%	0.15

Bold type indicates a significant difference.

DC, discharge; NICU, neonatal intensive care unit; OR, odds ratio; SES, socioeconomic status.

Table 2.

Continuous Variable Characteristics of Very Low Birth Weight Infants and Breastmilk Feeding Initiation, Breastfeeding, and Breastmilk Feeds at Discharge

Continuous variable	Were breastmilk feeds initiated?	P value for univariate analysis	Did the mother breastfeed the infant while in the NICU?	P value for univariate analysis	Did the mother continue to provide breastmilk until DC?	P value for univariate analysis
Mean LOS
Yes	69.3 ± 27.25	0.03	58.6 ± 22.5	< 0.01	55.3 ± 23.9	0.01
No	51.9 ± 0.03	0.03	80.6 ± 27.7	< 0.01	76.1 ± 26.4	0.01
Mean BW
Yes	1,022 ± 270.9	0.26	1,122 ± 250.5	< 0.01	1,082 ± 253.9	0.27
No	1,100 ± 278.1	0.26	913.3 ± 253	< 0.01	992 ± 277.1	0.27
Mean EGA
Yes	28.1 ± 2.7	0.07	28.8 ± 2.2	0.01/0.03/1	29.1 ± 2.3	0.02
No	29.3 ± 2.2	0.07	27.3 ± 3	0.01/0.03/1	27.6 ± 2.8	0.02
Mean maternal age
Yes	26.1 ± 7.0	0.83	28.4 ± 8.0	0.06	30.4 ± 7.7	0.01/< 0.01/1.1
No	24.9 ± 5.9	0.83	58.6 ± 22.5	0.06	24.1 ± 5.7	0.01/< 0.01/1.1

Bold type indicates a significant difference.

BW, birth weight; EGA, estimated gestational age; LOS, length of stay.

Associations were found between breastmilk feeds at discharge and socioeconomic status (p = 0.01), race (p ≤ 0.01), marital status (p = 0.04), length of stay (p = 0.01), estimated gestational age at birth (p = 0.02), and maternal age (p = 0.01). However, when these factors were put into a multivariate model (Tables 1 and 2), only race (p < 0.01) and maternal age (p < 0.01) remained significantly associated with breastmilk feeds at discharge. The odds ratio for Caucasian race was 7.6, and the odds ratio for maternal age was 1.1.

Associations were found between breastfeeding in the NICU and socioeconomic status (p = 0.01), race (p = 0.01), marital status (p = 0.02), length of stay (p ≤ 0.01), birth weight (p ≤ 0.01), and estimated gestational age (p = 0.01). When these factors were put in a multivariate model, socioeconomic status (p < 0.01), race (p = 0.01), and birth weight (p = 0.01) remained significant (Tables 1 and 2). The odds ratio for higher socioeconomic status was 15, for Caucasian race was 6.9, and for birth weight was 1.

No associations were found to influence if a mother has the first feeding at the breast, nor were there any associations with gestational age at first breastfeed.

Discussion

Although initial analyses indicated associations between length of stay and all breastfeeding outcome variables, when other variables were controlled for in multivariate analysis, length of stay was no longer significantly associated with breastmilk feeding initiation, direct breastfeeding, and breastmilk feeding at discharge. Length of stay, therefore, is not an independent predictor of breastfeeding practices in VLBW infants. These findings contrast with other research findings that have identified shorter length of stay and birth weight to be some of the strongest predictors of breastfeeding failure.^13,20,22 Success with breastfeeding can be achieved, even in those infants with longer length of stays. There are other factors that appear to be driving breastmilk feeding and breastfeeding success in VLBW infants.

This study demonstrates a high rate of breastmilk feeding initiation of 78% among VLBW infants hospitalized in the NICU, compared to rates in the general public. This may reflect the mothers' recognition of the fragile health of the infant who may benefit to a greater extent from breastmilk and supports the suggestion that mothers provide breastmilk to attempt to counteract the harm from premature birth.²³ This study's breastmilk feeding initiation rate is comparable to other research findings, which have documented rates of breastmilk feeding initiation in the NICU at 64%,²⁴ 72.9%,²⁵ and 83%.²⁶

Factors that were associated with breastmilk feeding initiation were multiple-infant birth and married marital status. Mothers of multiples were 4.4 times more likely to have breastmilk feedings initiated than singleton pregnancies, and infants from married mothers were 7.7 times more likely to initiate breastmilk feedings than infants from unwed mothers. This supports the findings from other studies that have determined higher breastmilk feeding initiation rates among married mothers and mothers of multiples.^17,27 Unwed mothers should be a targeted risk group for education prior to and immediately after birth to improve their understanding of the benefits and implications for breastmilk feeding and to aim to increase breastmilk feeding initiation in VLBW infants.

The paucity of direct breastfeeding in the NICU, even in those mothers who have maintained a milk supply until the infant is near term equivalent, is an important area for future research. Only 52% of infants whose mothers initiated breastmilk feedings had the experience of direct breastfeeding in the hospital. This is comparable to other studies that have documented direct breastfeeding rates between 27% and 48%.^19,23,25,28 Perhaps with the methodical approach in the NICU of pumping, tube feeding, and advancing to oral feeds, mothers are not enabled in the breastfeeding process, even when direct breastfeeding is feasible.

Non–African American mothers were seven times more likely to breastfeed while in the hospital. In addition, mothers of higher socioeconomic status were 15.5 times more likely to breastfeed while in the hospital. Targeted interventions to promote direct breastfeeding in the NICU are warranted for all mothers of VLBW infants, but African American mothers and mothers of lower socioeconomic status have the greatest needs. Birth weight was significant for no effects on direct breastfeeding while in the hospital. No relationship between the incidence of breastfeeding among infants of higher or lower birth weight provides some support for breastfeeding for all mothers of VLBW infants, regardless of birth weight or gestational age.

There is a large drop in the percentage of mothers who initiate breastmilk feedings (78%) to the number of mothers still providing breastmilk at discharge (48%), which highlights that there are many challenges associated with maintaining a milk supply and providing human milk through until discharge. The rate of breastmilk feedings at discharge (48%) was calculated only for infants who had breastmilk feedings initiated and thus would be lower if calculated for all infants in the NICU, as in previous studies. It is comparable to other research findings, which documented breastmilk feedings at discharge to be 38%,²⁵ 55%,²⁹ and 60%.²⁰ Conversely, the average duration of breastmilk feedings was 43 days, which was also comparable to other studies.¹⁸

Non–African American infants were 7.6 times more likely to continue to have breastmilk at discharge compared to African American infants. In addition, increasing maternal age resulted in a 10% increase in the incidence of breastmilk feeding at discharge. This supports the findings of other research, which has identified increased success among older mothers and among Caucasian mothers.^14,17 Younger mothers have a strong presence in the NICU, as they have an increased risk for premature birth. Twenty percent of mothers in this study were teenage mothers. In addition, nearly half (49%) of the infants in this study were African American. With fewer than half of mothers who initiated breastmilk feedings succeeding with breastmilk feedings until discharge, it is evident that better supports and interventions are needed to promote longevity of breastmilk feedings in this fragile population, especially in younger and African American mothers.

No associations were found between mother and infant factors and gestational age at first breastfeeding and whether the first oral feeding was at the breast. These factors are perhaps those that can be most easily changed through healthcare professional interventions and encouragement. If all mothers received support and encouragement independent of maternal/infant factors, it would indicate that mother and infant factors can perhaps be made less important with targeted interventions and that mothers can overcome the barriers to maintaining breastfeeding to the time of hospital discharge in this complex and challenging environment.

Despite the challenges associated with long-term breastmilk feedings in the NICU, it is imperative that interventions be developed and implemented. Some strategies that could change the duration of human milk feedings in the NICU could be to simply promote the transition to breastfeeding in the hospital. The transition to breastfeeding in the tenuous environment of the NICU requires the assistance of healthcare professionals. The attitudes of healthcare professionals regarding modes of feeding have a significant impact on the feeding choices that mothers make,³⁰ indicating that healthcare education and skill development could be an important intervention to support breastfeeding among mothers and infants in the NICU. Mothers learn how to parent and build foundations in the NICU for how they will care for their infant, and without success with breastfeeding in the NICU, many mothers will never make the transition from providing breastmilk for their baby to breastfeeding. With the paucity of breastfeeding (putting the infant to breast) in the NICU, it is of great interest to determine the predictive effect of breastfeeding on breastmilk feedings at discharge, milk production, amount of breastmilk feedings in the hospital, and the effect on maternal and child health. Likewise, it would be of great interest to determine if there are any negative effects of not enabling breastfeeding on the ability to maintain the milk supply, success of breastfeeding at discharge and beyond, and the ability to transition from breastmilk feeds to direct breastfeeding.

Conclusions

The major findings of this study are that maternal and infant factors are associated with decisions to provide breastmilk, with commitment and success with breastmilk feeds through discharge, and with making the transition to direct breastfeeding in the hospital.

Predictors of breastfeeding were associated with maternal and demographic factors, but infant factors, such as birth weight and length of stay, failed to be important factors associated with breastfeeding in the NICU. This gives support for the process of breastfeeding being possible in the NICU environment. By understanding predictive factors associated with certain breastfeeding outcomes, mothers with certain demographic characteristics can be identified for more successful interventions.

This study encourages a closer look at breastfeeding interventions in the NICU. By looking past predictive factors and focusing attention and support on enabling mothers, perhaps we can transcend maternal age, race, and marital status to increase rates of breastfeeding. In addition, we can work to come up with adequate interventions for high-risk infants so that, when compared with full-term infants, birth weight, estimated gestational age, and length of stay are no longer factors associated with failed breastfeeding. Interventions in the NICU should adequately educate and support caregivers, families, and society in the context of the high-risk environment and enable mothers to transition to breastfeeding as soon as feasible to promote success until discharge and beyond. Through adequate interventions, more premature infants can have the long-term health and developmental benefits associated with breastmilk.

Footnotes

Disclosure Statement

No competing financial interests exist.

References

Breastfeeding and the use of human milk. American Academy of Pediatrics. Work Group on Breastfeeding. Pediatrics, 1997; 100:1035–1039.

Chen

, Rogan

. Breastfeeding and the risk of postneonatal death in the United States. Pediatrics, 2004; 113:e435–e439.

Laubereau

, Brockow

, Zirngibl

et al. Effect of breast-feeding on the development of atopic dermatitis during the first 3 years of life—results from the GINI-birth cohort study. J Pediatr, 2004; 144:602–607.

Hylander

, Strobino

, Dhanireddy

. Human milk feedings and infection among very low birth weight infants. Pediatrics, 1998; 102:E38.

Schanler

. The use of human milk for premature infants. Pediatr Clin North Am, 2001; 48:207–219.

Kemp

, Kakakios

. Asthma prevention: Breast is best? J Paediatr Child Health, 2004; 40:337–339.

James

, Dobson

. Position of the American Dietetic Association: Promoting and supporting breastfeeding. J Am Diet Assoc, 2005; 105:810–818.

Ball

, Wright

. Health care costs of formula-feeding in the first year of life. Pediatrics, 1999; 103:870–876.

Díaz

Gómez M

, Ramos Acosta

, Rico Sevillano

et al.

[Breast feeding and length of hospitalization]

Rev Enferm, 1997; 20:11–14.

10.

Lanari

, Papa

, Venturi

et al.

[Neonatal sepsis]

Recenti Prog Med, 2001; 92:690–695.

11.

Hart

, Boylan

, Carroll

et al. Brief report: breast-fed one-week-olds demonstrate superior neurobehavioral organization. J Pediatr Psychol, 2003; 28:529–534.

12.

Gómez-Sanchiz

, Cañete

, Rodero

et al. Influence of breast-feeding on mental and psychomotor development. Clin Pediatr (Phila), 2003; 42:35–42.

13.

Espy

, Senn

. Incidence and correlates of breast milk feeding in hospitalized preterm infants. Soc Sci Med, 2003; 57:1421–1428.

14.

Powers

, Bloom

, Peabody

et al. Site of care influences breastmilk feedings at NICU discharge. J Perinatol, 2003; 23:10–13.

15.

Scott

, Binns

, Graham

et al. Temporal changes in the determinants of breastfeeding initiation. Birth, 2006; 33:37–45.

16.

de Azevedo

, Mendes

. [Maintenance of lactation: A challenge for hospitalized premature infant's mothers] Rev Gaucha Enferm, 2008; 29:68–75.

17.

Lee

, Gould

. Factors influencing breast milk versus formula feeding at discharge for very low birth weight infants in California. J Pediatr, 2009; 155:657–662e1–e2.

18.

Killersreiter

, Grimmer

, Bührer

et al. Early cessation of breast milk feeding in very low birthweight infants. Early Hum Dev, 2001; 60:193–205.

19.

Smith

, Durkin

, Hinton

et al. Initiation of breastfeeding among mothers of very low birth weight infants. Pediatrics, 2003; 111:1337–1342.

20.

Kirchner

, Jeitler

, Waldhör

et al. Long hospitalization is the most important risk factor for early weaning from breast milk in premature babies. Acta Paediatr, 2009; 98:981–984.

21.

Pineda

, Foss

, Richards

, Pane

. Breastfeeding changes for VLBW infants in the NICU following staff education. Neonatal Network, 2009; 28:311–319.

22.

Hwang

, Chung

, Kang

et al.

[Factors affecting breastfeeding rate and duration]

J Prev Med Public Health, 2006; 39:74–80.

23.

Lee

, Lee

, Kuo

. The experiences of mothers in breastfeeding their very low birth weight infants. J Adv Nurs, 2009; 65:2523–2531.

24.

Byrne

, Hull

. Breast milk for preterm infants. Prof Care Mother Child, 1996; 6:39–42–45.

25.

Yip

, Lee

, Sheehy

. Breast-feeding in neonatal intensive care. J Paediatr Child Health, 1996; 32:296–298.

26.

Meier

, Engstrom

, Mingolelli

et al. The Rush Mothers' Milk Club: Breastfeeding interventions for mothers with very-low-birth-weight infants. J Obstet Gynecol Neonatal Nurs, 2004; 33:164–174.

27.

Lessen

, Crivelli-Kovach

. Prediction of initiation and duration of breast-feeding for neonates admitted to the neonatal intensive care unit. J Perinat Neonatal Nurs, 2007; 21:256–266.

28.

Furman

, Minich

, Hack

. Breastfeeding of very low birth weight infants. J Hum Lact, 1998; 14:29–34.

29.

Davanzo

, Ronfani

, Brovedani

et al. Breast feeding very-low-birthweight infants at discharge: A multicentre study using WHO definitions. Paediatr Perinat Epidemiol, 2009; 23:591–596.

30.

, Eren

, Lowdermilk

et al. Knowledge and attitudes of pediatric office nursing staff about breastfeeding. J Hum Lact, 2000; 16:210–215.