Knowledge of Breastfeeding Recommendations and Breastfeeding Duration: A Survival Analysis on Infant Feeding Practices II

Abstract

Background:

According to the American Academy of Pediatrics, infants should be exclusively breastfed for the first 6 months of life followed by breastfeeding with complementary food for up to 2 years of age or beyond. Knowledge of breastfeeding recommendations may greatly influence breastfeeding practices; however, the association between a woman's knowledge of exclusive breastfeeding recommendations and breastfeeding duration is not well explored. This study aims to examine the relationship between knowledge of exclusive breastfeeding recommendations before birth and breastfeeding duration.

Materials and Methods:

Data from the prospective, longitudinal 2005–2007 Infant Feeding and Practices Study II were analyzed (N = 2,935). Knowledge of national breastfeeding recommendations (yes; no) was based on a survey question asking the recommended length of breastfeeding. Breastfeeding duration was reported in weeks and was analyzed as any breastfeeding or exclusive breastfeeding. Cox proportional hazard models were used to obtain crude and adjusted hazard ratios (HRs) and 95% confidence limits (CLs).

Results:

Overall, 91.7% of women did not exclusively breastfeed the recommended duration and one in five (21.4%) did not know current breastfeeding recommendations. Women without knowledge of exclusive breastfeeding recommendations had a lower probability of breastfeeding compared with women with knowledge of breastfeeding recommendations. Furthermore, after adjusting for confounders, women without knowledge of exclusive breastfeeding recommendations had 11% higher risk (HR = 1.11; 95% CL = 1.01–1.23) of ceasing breastfeeding at every point in time compared with women who reported knowledge of breastfeeding recommendations while exclusive breastfeeding was not significant.

Conclusions:

Findings from this study provide evidence that a mother's knowledge of exclusive breastfeeding recommendations impacts breastfeeding practices. Healthcare providers and public health professionals should educate mothers about breastfeeding.

Introduction

Breastfeeding is considered one of the best ways to reduce infant mortality and morbidity.¹ The short and long-term advantages of breastfeeding are well documented^2–4; yet, only a small proportion of U.S. women follow national breastfeeding recommendations.⁵ According to the American Academy of Pediatrics (AAP), infants should be exclusively breastfed for the first 6 months of life followed by breastfeeding with complementary food for up to 2 years of age or beyond.⁶ Furthermore, Healthy People 2020, a national health promotion and disease prevention initiative, designed to improve public health, identified goals for increasing breastfeeding rates. These goals aim to increase the proportion of women who exclusively breastfeed for 3 months to 46.2% and the recommended 6-month duration to 25.5%. Moreover, Healthy People 2020 wants to increase the prevalence of any breastfeeding at 12 months to 34.1%.⁷

Various studies have documented medical and neurodevelopmental advantages of breastfeeding for mothers and their offspring. For example, children who are exclusively breastfed 6 months or more have decreased risk of pneumonia, asthma, bronchiolitis, otitis media, serious colds, allergies, and ear and throat infections.^2–4,8,9 Furthermore, mothers who breastfeed have a reduced risk of postpartum depression, type 2 diabetes mellitus, rheumatoid arthritis, hypertension, cardiovascular disease, and breast and ovarian cancer.^8,10–14

Despite widespread acceptance of the benefits of breastfeeding, less than a quarter (19%) of U.S. mothers are breastfeeding the recommended 6-month duration.⁶ A number of factors, such as race/ethnicity^15,16 and socioeconomic status,¹⁷ have been shown to impact breastfeeding duration. In addition, several studies demonstrate that the major causes of premature weaning are perceived insufficient milk supply, mothers' concerns about lactation and nutrition issues, work-related barriers, lack of a perceived support system (personal or professional), lack of confidence and commitment, and inadequate prenatal care.^10,18–21

A mother's knowledge of breastfeeding recommendations also has the potential to impact breastfeeding practices. The information and advice mothers receive regarding infant feeding come from a variety of sources and vary in content. Even though mothers tend to adhere to advice from health professionals, the attitude of the health professional about their role in breastfeeding promotion and support varies. For example, a study conducted in 1999 found that pediatricians reported recommending exclusive breastfeeding 65% of the time, 20% made no recommendation, 13% recommended breastfeeding with formula, and 2% recommended formula feeding only.²² These variations may explain differing knowledge among mothers regarding breastfeeding recommendations—which may play a role in breastfeeding outcomes.

To authors' knowledge, previous studies investigating factors influencing breastfeeding duration did not consider knowledge of exclusive breastfeeding recommendations. Since knowledge can be easily changed, more research is needed to better understand how mothers' knowledge of exclusive breastfeeding recommendations relates to their breastfeeding practices. Therefore, this study explores if improving mothers' knowledge of exclusive breastfeeding recommendations is associated with a longer breastfeeding duration using any breastfeeding (breast milk in combination with other supplements) and exclusive breastfeeding.

Materials and Methods

The current study used data from the Infant Feeding and Practices Study II (IFPS II), a longitudinal prospective study that collected information from May 2005 through June 2007 in the United States. A nationally representative consumer opinion panel of 500,000 households was used to identify participants that resulted in a sample of 4,902 pregnant women at the beginning of the study, with ∼2,000 women continuing through the first year of the infant's life.²³ To be included in the study, mothers were at least 18 years old at the time of the prenatal questionnaire, had a full term, had good maternal and child health at birth, and the infant could not have or develop a condition or illness that could impact feeding at birth in the first year of life. Mailed questionnaires were sent to mothers to collect information on maternal and child health, infant feeding behaviors, and a mother's diet. Additional information on IFPS II methodology²³ and questionnaires²⁴ are available elsewhere.

Data for this analysis excluded women who did not respond to survey questions used to determine knowledge of exclusive breastfeeding recommendations and breastfeeding duration (N = 1,967)—leaving 2,935 women for analysis. Knowledge of the exclusive breastfeeding duration recommendation (breastfeed <6 months; breastfeed 6 months or more) was based on the survey question, “As best you know, what is the recommended number of months to exclusively breastfeed a baby, meaning the baby is only fed breast milk?”

Breastfeeding duration will measure the number of weeks the infant was breastfed and was based upon three survey questions, “Did you ever breastfeed this baby (or feed this baby your pumped milk)?,” “Have you completely stopped breastfeeding and pumping milk for your baby?,” and “How old was your baby when you completely stopped breastfeeding and pumping milk?” If mothers were still breastfeeding at the time of the last interview (at 12 months postpartum) (N = 917), the following survey question was ascertained at the 6-year follow up and was used to determine breastfeeding duration, “How old was your 6-year-old when the following happened? He or she stopped being fed breast milk, including pumped breast milk.”

Exclusive breastfeeding was defined as the infant receiving breast milk and no other food or drink—which is consistent with international organizations such as the World Health Organization (WHO). Exclusive breastfeeding for the hospital stay was determined using two questions: “While you were in the hospital or birth center, was your baby fed water, formula, or sugar water at any time?,” and “When you left the hospital or birth center, how were you feeding your baby?.” Women who did not feed their baby water, formula, or sugar water at any time in the hospital and were only feeding their baby breast milk were categorized as “exclusive breastfeeding” for their time at the hospital. Exclusive breastfeeding after discharge utilized the food frequency checklist which asked, “In the past 7 days, how often was your baby fed each food listed below? Include feedings by everyone who feeds the baby and include snacks and night-time feedings.” Mothers were provided a list of food that the infant could consume and filled in columns asking the frequency of feeding per day or per week.¹⁹ If women only reported feeding their infant breast milk, they were categorized as “exclusive.” This question was asked approximately every month postpartum. Once a participant indicated she was not exclusively breastfeeding, IFPS II estimated the midpoint of the infant age on the last questionnaire, where the mother was exclusively breastfeeding.

Various factors were considered as potential confounders as determined in the literature.^25–29 These include marital status (married; not married), maternal race (White; Black; Hispanic; other, including Asian/pacific islander), maternal age (18–24; 25–29; 30–34; 35–45 years), maternal education (less than high school; high school graduate; 1–3 years of college; college graduate), income (<$20,000; $20,000–$49,999; more than $50,000), prepregnancy body mass index (underweight [<18.5 kg/m²]; normal weight [18.5–24.9 kg/m²]; overweight [25.0–29.9 kg/m²]; obese [30.0+ kg/m²]), postnatal participation in the Special Supplemental Nutrition Program from women, infants, and children (WIC) program (yes; no), prenatal healthcare provider (obstetrician; other physician; midwife; or other healthcare provider), and intention to breastfeed (yes; no).

Descriptive statistics were used to examine the distribution of data. A crude Cox proportional hazard (PH) model was used to determine factors associated with any breastfeeding and exclusive breastfeeding. Kaplan–Meier estimated the survival function (survival curve). The PH assumption was verified using the Kolmogorov-type supremum test, which was nonsignificant (p = 0.31). Multicollinearity was tested for all confounders in the parsimonious model and none of the potential confounders reached a variance inflation factor (VIF) of 5. Breastfeeding intention, maternal education, and maternal race were assessed as effect modifiers for any breastfeeding and exclusive breastfeeding. Only breastfeeding intention was determined as an effect modifier (p = 0.045) for any breastfeeding. Age, marital status, race, education, income, prenatal and postnatal participation in WIC, and prepregnancy body mass index were assessed as potential confounders. To be included in the final model, a potential confounder had to change the crude estimate by at least 10%.³⁰ However, none of the potential confounders met this rule. Therefore, all known confounders identified from prior literature^25–27 were included in the model. Cox PH models were also used to obtain crude and adjusted hazard ratios (HRs) and 95% confidence limits (CLs) for the main exposure and outcomes. Furthermore, the log-rank test was utilized to test equality of survival. All analyses were conducted using SAS version 9.4 statistical software (SAS, Cary, NC).

Results

The majority of the respondents were married (79.3%), Non-Hispanic White (84.7%), and had at least some college education (79.6%). Approximately a quarter (23.9%) did not breastfeed and ∼1 in 10 (8.3%) exclusively breastfed the recommended 6-month duration (Table 1). Approximately one in five women (21.4%) did not know the national breastfeeding recommendations. Table 1 displays the distribution of maternal characteristics by mothers' knowledge of exclusive breastfeeding recommendations. Mothers who had knowledge of exclusive breastfeeding recommendations had a higher prevalence of women who were college graduates, of higher income, did not participate in WIC, and used a midwife or other healthcare provider for prenatal services. Table 2 shows factors that are associated with any breastfeeding and exclusive breastfeeding. For example, unmarried women had 56% higher risk (HR = 1.56, 95% s = 1.42–1.71) of discontinuing any breastfeeding before 6 months compared with married women. Furthermore, unmarried women had 39% higher risk (HR = 1.39, 95% CL = 1.26–1.53) of discontinuing exclusive breastfeeding compared with married women.

Table 1.

Distribution of Maternal Characteristics by Mothers' Knowledge of Breastfeeding Recommendations

Characteristics	Overall Percent^a (N = 2,935)	No maternal knowledge Percent^a (N = 628)	Maternal knowledge Percent^a (N = 2,307)	Chi square (p)
Age				0.0168
18–24 Years	23.3	27.4	22.2
25–29 Years	34.0	34.4	33.9
30–34 Years	27.5	25.8	28.0
35–45 Years	15.2	12.5	15.9
Marital status				0.4958
Married	79.3	78.3	79.6
Not married	20.7	21.7	20.4
Maternal race				0.7879
White, Non-Hispanic	84.7	84.5	84.7
Black, Non-Hispanic	4.7	4.1	4.9
Hispanic	6.1	6.8	6.0
Other	4.5	4.6	4.5
Maternal education				0.0008
Less than high school	3.0	3.5	2.9
High school	17.4	19.8	16.7
1–3 Years of college	40.5	45.0	39.3
College graduate	39.1	31.7	41.1
Income				0.0262
<$20,000	13.6	15.5	13.1
$20,000−$49,999	43.3	46.0	42.6
≥$50,000	43.1	38.5	44.3
Prepregnancy BMI				0.9764
Underweight (<18.5 kg/m²)	4.7	4.9	4.6
Normal weight (18.5–24.9 kg/m²)	45.5	45.1	45.6
Overweight (25.0–29.9 (kg/m²)	26.2	25.9	26.3
Obese (30.0+ kg/m²)	23.7	24.2	23.5
Postnatal WIC participation				0.0086
No	60.0	55.4	61.2
Yes	40.0	44.6	38.8
Prenatal provider				0.0167
Obstetrician	83.9	84.2	83.8
Family doctor or other physician	7.3	9.2	6.8
Midwife or other healthcare provider	8.8	6.6	9.4
Breastfeeding duration (any)				0.0007
Never breastfed	13.7	17.8	12.6
Breastfed <6 months	45.0	45.9	44.8
Breastfed 6 or more months	41.2	36.3	42.6
Breastfeeding duration (exclusive)				0.001
Never breastfed	23.9	30.4	22.1
Breastfed <6 months	67.8	64.2	68.8
Breastfed 6 or more months	8.3	5.4	9.1

Not all percentages sum to 100% due to rounding.

BMI, body mass index; WIC, women, infants, and children.

Table 2.

Factors Associated with Breastfeeding Duration

	Any breastfeeding	Exclusive breastfeeding
Characteristics	Hazard ratio (95% confidence limit)
Age
18–24 Years	1.71 (1.55 − 1. 90)	1.32 (1.19 − 1.46)
25–29 Years	1.05 (0.96 − 1.16)	0.97 (0.89 − 1.07)
30–34 Years	Reference
35–45 Years	0.88 (0.79 − 0.99)	0.97 (0.86 − 1.09)
Marital status
Married	Reference
Not married	1.56 (1.42 − 1.71)	1.39 (1.26−1.53)
Maternal race
White, Non-Hispanic	Reference
Black, Non-Hispanic	1.32 (1.11 − 1.57)	1.51 (1.27−1.80)
Hispanic	1.08 (0.93 − 1.26)	1.23 (1.05 − 1.43)
Other	0.91 (0.76 − 1.09)	1.10 (0.92 − 1.31)
Maternal education
Less than high school	1.83 (1.46 − 2.30)	1.50 (1.20−1.88)
High school	1.83 (1.67 − 2.04)	1.43 (1.28 − 1.60)
1–3 Years of college	1.41 (1.29 − 1.53)	1.22 (1.11−1.33)
College graduate	Reference
Income
<$20,000	1.42 (1.27 − 1.59)	1.16 (1.04−1.30)
$20,000−$49, 999	1.13 (1.04 − 1.22)	1.05 (0.97 − 1.14)
≥$50,000	Reference
Prepregnancy BMI
Underweight (<18.5 kg/m²)	1.16 (0.97 − 1.38)	1.08 (0.90 − 1.29)
Normal weight (18.5–24.9 kg/m²)	Reference
Overweight (25.0–29.9 kg/m²)	1.10 (1.00 − 1.20)	1.13 (1.04 − 1.24)
Obese (30.0+ kg/m²)	1.15 (1.05 − 1.26)	1.20 (1.10−1.32)
Postnatal WIC participation
No	Reference
Yes	1.46 (1.35 − 1.57)	1.28 (1.19 − 1.38)
Prenatal provider
Obstetrician	Reference
Family doctor or other physician	1.07 (0.93 − 1.23)	1.00 (0.87 − 1.16)
Midwife or other healthcare provider	0.78 (0.69 − 0.89)	0.72 (0.63 − 0.82)
Breastfeeding intention
Breastfeeding only	Reference
Formula or combination	2.63 (2.43 − 2.84)	2.05 (1.89 − 2.23)

Bold estimates are significant.

The survival curves (not provided) showed that at each point in time, women without knowledge of exclusive breastfeeding recommendations had a lower probability of breastfeeding relative to women with knowledge of breastfeeding recommendations. Furthermore, the mean breastfeeding duration among women with knowledge of exclusive breastfeeding recommendations was 23 weeks; standard error (SE) = 0.43 (5.8 months) compared with a mean duration of ∼19.9 weeks; SE = 0.79 (5 months) for women without knowledge of breastfeeding recommendations (p = 0.0006).

The unadjusted analysis showed that women without knowledge of exclusive breastfeeding recommendations had 16% higher risk (HR = 1.16; 95% CL = 1.07–1.27) of discontinuing any breastfeeding before 6 months than women with knowledge of breastfeeding recommendations. Additionally, women without knowledge of exclusive breastfeeding recommendations had 11% higher risk (HR = 1.11; 95% CL = 1.02–1.22) of discontinuing exclusive breastfeeding compared with women with knowledge of breastfeeding recommendations. After adjusting for age, marital status, maternal race, maternal education, income, and prenatal healthcare provider, the association for any breastfeeding was slightly attenuated, but remained statistically significant, whereas exclusive breastfeeding lost significance. Women without knowledge of exclusive breastfeeding recommendations had 11% higher risk (HR = 1.11; 95% CL = 1.01–1.23) of discontinuing any breastfeeding before 6 months postpartum compared with women who reported knowledge of breastfeeding recommendations (Table 3).

Table 3.

Proportional Hazards of Breastfeeding Duration

Hazard ratio (95% confidence limit)
	Unadjusted	Adjusted
Any breastfeeding^a
Mothers who report breastfeeding recommendations are <6 months^b	1.16 (1.07 − 1.27)^d	1.11 (1.01 − 1.23)^e
Exclusive breastfeeding^c
Mothers who report breastfeeding recommendations are <6 months^b	1.11 (1.02 − 1.22)^e	1.04 (0.94 − 1.14)

Adjusted for age, marital status, maternal race, maternal education, income, prepregnancy body mass index, postnatal participation in the Special Supplemental Nutrition Program from WIC program, and prenatal healthcare provider.

Compared with mothers who report breastfeeding recommendations are at least 6 months.

Adjusted for age, marital status, maternal race, maternal education, income, prenatal healthcare provider, prepregnancy body mass index, postnatal participation in the Special Supplemental Nutrition Program from WIC program, and breastfeeding intention.

p < 0.001; ^ep < 0.05.

Discussion

Findings from the current study revealed that the majority of women in the study were aware of the recommended 6-month exclusive breastfeeding duration, yet only 1 in 10 women exclusively breastfed the recommended 6-month duration. The results also showed that women who were not knowledgeable about exclusive breastfeeding recommendations had a lower probability of any breastfeeding relative to women who were knowledgeable about exclusive breastfeeding recommendations. However, no relationship was found for exclusive breastfeeding. Additionally, women who were not knowledgeable about breastfeeding recommendations had a shorter mean duration of breastfeeding. Overall, having knowledge of the exclusive 6-month breastfeeding recommendation has a significant effect on duration of any breastfeeding, but not on exclusive breastfeeding duration.

These findings are consistent with recent literature showing similar associations and prevalence rates. For example, a study conducted in Belgium reported an independent association between women who were knowledgeable about WHO breastfeeding recommendations and the duration of any breastfeeding.³¹ Furthermore, the prevalence of breastfeeding duration and knowledge of breastfeeding recommendations in the current study are consistent with findings from the Centers for Disease Control and Prevention (CDC) 2014 Breastfeeding Report Card that reported less than half (49%) of infants being breastfed at 6 months in the United States,³² despite the majority of women being aware that breastfeeding is the best source of nutrition for most infants.³³ Similarly, a longitudinal study conducted by Wen et al. among 201 first-time mothers who participated in the Healthy Beginnings Trial in Australia revealed 60% of women were aware of breastfeeding recommendations, yet only 46% breastfed their babies at 6 months.³⁴

The disparity between women's knowledge about exclusive breastfeeding recommendations and their ability to adhere to these recommendations may be due to lack of knowledge about breastfeeding benefits, misperceptions about infant satisfaction with breast milk, lack of necessary skills on how to effectively breastfeed infants, and the inconvenience of breastfeeding.¹⁸ For example, in a nationally representative study that examined the attitudes of women enrolled in the Special Supplemental Nutrition Program for WIC, McCann et al. reported that only 36% of women thought breastfeeding would protect their baby against diarrhea.³⁵ Additionally, despite women's knowledge about breastfeeding recommendations, women may not breastfeed the recommended duration because they believe that breast milk alone is not sufficient to effectively satisfy the baby.¹⁸ Furthermore, many mothers lack the necessary skills on how to breastfeed their infants. Breastfeeding, although labeled as “natural,” is an art that has to be learned by both the mother and the newborn.³³ For instance, being able to hold and position the baby at breast, and achieve an effective latch are skills that need to be learned by the mother. Another major confounder may be the conflicting information mothers receive from magazines, friends, and families, and other providers about the correct time to introduce solids into the infant's diet,^36–38—which could lead to mothers prematurely ceasing exclusive breastfeeding.

Perhaps the most interesting finding from the current study is that women who had knowledge of exclusive breastfeeding recommendations were associated with any breastfeeding, whereas exclusive breastfeeding did not show statistical significance. This could be partially explained by the time commitment breastfeeding entails. Specifically, mothers who return to work or school while nursing¹⁸ may face time constraint and convenience issues. For example, a pilot study found perceived convenience was associated with breastfeeding commitment.³⁹ Regardless of knowledge, the activities mothers participate in during the first year of their child's life could explain the shift from exclusive breastfeeding to breastfeeding in combination with formula or other foods.

This study revealed important findings that have clinical relevance. The use of a large sample of women is a major strength of the study. The longitudinal nature of the dataset enabled women to be followed until breastfeeding discontinuation. Furthermore, the prospective study design allowed temporality to be established. To the authors' knowledge, this is the first study to investigate the association between a mothers' knowledge of exclusive breastfeeding recommendations and subsequent breastfeeding practices in the United States. The current study highlights the importance of education and provides new insight for current and future breastfeeding interventions.

Despite its strengths, the current study should be viewed in light of a few limitations. The study sample is comprised predominantly of non-Hispanic White, well-educated and middle class to high income women, and thus, prevalence estimates may not be generalizable to all women in the United States. Also, breastfeeding duration and exclusivity is self-reported, which may have been prone to social desirability bias and nondifferential misclassification, as women wanting to be seen as being caring of their babies may have over-reported their breastfeeding duration. This could bias the results toward the null. However, previous literature has stated that maternal recall of breastfeeding initiation and duration is a valid and reliable estimate. A study conducted among Norwegian women found that women who recalled their breastfeeding duration 20 years after recording their breastfeeding duration on a questionnaire had a strong correlation (intraclass correlation coefficient [ICC] = 0.82, p < 0.001).⁴⁰ Additionally, smoking during pregnancy, facility where mother received prenatal care, number of prenatal care visits, self-efficacy, and alcohol use were not available in the data set, and may have affected the effect size.

Conclusion

Findings from this study provide evidence that improving mothers' knowledge of exclusive breastfeeding recommendations may encourage mothers to breastfeed their infants for the recommended 6-month duration. Results also highlight the need to educate younger mothers, low income earners, and mothers participating in the WIC program about breastfeeding recommendations. Additional research has shown that when healthcare providers are committed toward providing women with breastfeeding recommendations, women are more likely to breastfeed their babies according to these recommendations.⁴¹ Therefore, educating women about breastfeeding recommendations will require the full commitment of healthcare providers. Beyond educating women about breastfeeding recommendations, programs should also be put in place to address perceived barriers to breastfeeding in mothers. Further research should be conducted on what educational medium is the most affective at increasing breastfeeding knowledge.

Footnotes

Disclosure Statement

No competing financial interests exist.

References

León-Cava

, Lutter

, Ross

, et al. Quantifying the Benefits of Breastfeeding: A Summary of the Evidence. Washington, DC: PAHO, 2002.

Barclay

, Russell

, Wilson

, et al. Systematic review: The role of breastfeeding in the development of pediatric inflammatory bowel disease. J Pediatr, 2009; 155:421–426.

Chantry

, Howard

, Auinger

. Full breastfeeding duration and associated decrease in respiratory tract infection in US children. Pediatrics, 2006; 117:425–432.

Duijts

, Jaddoe

, Hofman

, et al. Prolonged and exclusive breastfeeding reduces the risk of infectious diseases in infancy. Pediatrics, 2010; 126:e18–e25.

Centers for Disease Control and Prevention.. Breastfeeding report card. Updated 2016. Available at www.cdc.gov/breastfeeding/data/reportcard.htm (accessed October 13, 2016).

Section on Breastfeeding. Breastfeeding and the use of human milk. Pediatrics, 2012; 129:e827–e841.

US Department of Health and Human Services.. Maternal, infant, and child health. Healthy People 2020, 2010; 2011. Available at https://www.healthypeople.gov/2020/topics-objectives/topic/maternal-infant-and-child-health/objectives

, Chung

, Raman

. Tufts-New England Medical Center Evidence-Based Practice Center. Breastfeeding and maternal and infant health outcomes in developed countries. Evid Rep Technol Assess (Full Rep), 2007; 153:1–186.

Bartick

, Schwarz

, Green

, et al. Suboptimal breastfeeding in the united states: Maternal and pediatric health outcomes and costs. Matern Child Nutr, 2016; 13:3–6.

10.

Henderson

, Evans

, Straton

, et al. Impact of postnatal depression on breastfeeding duration. Birth, 2003; 30:175–180.

11.

Schwarz

, Brown

, Creasman

, et al. Lactation and maternal risk of type 2 diabetes: A population-based study. Am J Med, 2010; 123:863.e1–e6.

12.

Karlson

, Mandl

, Hankinson

, et al. Do breast‐feeding and other reproductive factors influence future risk of rheumatoid arthritis?: Results from the nurses' health study. Arthritis Rheum, 2004; 50:3458–3467.

13.

Victora

, Bahl

, Barros

, et al. Breastfeeding in the 21st century: Epidemiology, mechanisms, and lifelong effect. Lancet, 2016; 387:475–490.

14.

Grummer‐Strawn

, Rollins

. Summarising the health effects of breastfeeding. Acta Paediatr, 2015; 104:1–2.

15.

Forste

, Weiss

, Lippincott

. The decision to breastfeed in the United States: Does race matter?. Pediatrics, 2001; 108:291–296.

16.

Celi

, Rich-Edwards

, Richardson

, et al. Immigration, race/ethnicity, and social and economic factors as predictors of breastfeeding initiation. Arch Pediatr Adolesc Med, 2005; 159:255–260.

17.

Heck

, Braveman

, Cubbin

, et al. Socioeconomic status and breastfeeding initiation among California mothers. Public Health Rep, 2006; 121:51–59.

18.

, Fein

, Chen

, et al. Why mothers stop breastfeeding: Mothers' self-reported reasons for stopping during the first year. Pediatrics, 2008; 122(Suppl. 2):S69–S76.

19.

Brodribb

, Fallon

, Hegney

, et al. Identifying predictors of the reasons women give for choosing to breastfeed. J Hum Lact, 2007; 23:338–344.

20.

Avery

, Zimmermann

, Underwood

, et al. Confident commitment is a key factor for sustained breastfeeding. Birth, 2009; 36:141–148.

21.

Brand

, Kothari

, Stark

. Factors related to breastfeeding discontinuation between hospital discharge and 2 weeks postpartum. J Perinat Educ, 2011; 20:36–44.

22.

Schanler

, O'Connor

, Lawrence

. Pediatricians' practices and attitudes regarding breastfeeding promotion. Pediatrics, 1999; 103:e35.

23.

Fein

, Labiner-Wolfe

, Shealy

, et al. Infant feeding practices study II: Study methods. Pediatrics, 2008; 122(Suppl. 2):S28–S35.

24.

Center for Disease Control and Prevention.. Infant feeding practices study II and its year six follow-up. Updated 2014. Available at www.cdc.gov/breastfeeding/data/ifps/index.htm (accessed February 16, 2016).

25.

Masho

, Cha

, Morris

. Prepregnancy obesity and breastfeeding noninitiation in the United States: An examination of racial and ethnic differences. Breastfeed Med, 2015; 10:253–262.

26.

Oddy

, Li

, Landsborough

, et al. The association of maternal overweight and obesity with breastfeeding duration. J Pediatr, 2006; 149:185–191.

27.

Scott

, Binns

, Oddy

, et al. Predictors of breastfeeding duration: Evidence from a cohort study. Pediatrics, 2006; 117:e646–e655.

28.

Wallenborn

, Masho

, Ratliff

. Paternal pregnancy intention and breastfeeding duration: Findings from the national survey of family growth. Matern Child Health J, 2016; 20:1–8.

29.

Masho

, Morris

, Wallenborn

. Role of marital status in the association between prepregnancy body mass index and breastfeeding duration. Womens Health Issues, 2016; 26:468–475.

30.

Rothman

, Greenland

, Lash

. Modern Epidemiology. Lippincott Williams & Wilkins, Philadelphia, 2008.

31.

Robert

, Coppieters

, Swennen

, et al. Breastfeeding duration: A survival analysis-data from a regional immunization survey. Biomed Res Int, 2014; 2014:529790.

32.

Centers for Disease Control and Prevention (CDC).. Breastfeeding report card 2014. Updated 2014. United States: Outcome Indicators available at www.cdc.gov/breastfeeding/data/reportcard.htm (Accessed August, 2016).

33.

Office of the Surgeon General (US), Centers for Disease Control and Prevention (US), Office on Women Health (US). The Surgeon General's Call to Action to Support Breastfeeding. Rockville (MD): Office of the Surgeon General (US); 2011. PubMed PMID: 21452448.

34.

Wen

, Simpson

, Rissel

, et al. Awareness of breastfeeding recommendations and duration of breastfeeding: Findings from the healthy beginnings trial. Breastfeed Med, 2012; 7:223–229.

35.

McCann

, Baydar

, Williams

. Breastfeeding attitudes and reported problems in a national sample of WIC participants. J Hum Lact, 2007; 23:314–324.

36.

Eisenberg

, Bair-Merritt

, Colson

, et al. Maternal report of advice received for infant care. Pediatrics, 2015; 136:e315–e322.

37.

McInnes

, Chambers

. Supporting breastfeeding mothers: Qualitative synthesis. J Adv Nurs, 2008; 62:407–427.

38.

Bäckström

, Wahn

EIH

, Ekström

. Two sides of breastfeeding support: Experiences of women and midwives. Int Breastfeed J, 2010; 5:20.

39.

Ricotti

, Apekey

, Gatenby

. Factors that influence commitment to breastfeeding: A pilot study. J Health Visit, 2015; 3:216–223.

40.

Natland

, Andersen

, Nilsen

TIL

, et al. Maternal recall of breastfeeding duration twenty years after delivery. BMC Med Res Methodol, 2012; 12:1.

41.

Stuebe

. Optimizing support for breastfeeding as part of obstetric practice. Obstet Gynecol, 2016; 127:E86–E92.