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Journal of Human Lactation

DOI: 10.1177/0890334406286992

2006; 22; 166J Hum Lact Jennifer L. Bodnarchuk, Warren O. Eaton and Patricia J. Martens

Transitions in Breastfeeding: Daily Parent Diaries Provide Evidence of Behavior Over Time

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166

“Breast milk can quite readily be described as broad-spectrum medicine as well as nutrition,” 1(p 411) and it and

the act of breastfeeding have been designed throughevolutionary history to provide optimal outcomes forthe developing infant as well as for the mother. 2 Modernscience has not yet designed an infant formula that canrival this system, and infants who do not receive breastmilk or experience breastfeeding have, in general, worseoutcomes than infants who do. Thus, several countriesand the World Health Organization have policies inplace that support and recommend breastfeeding. 3-5

However, no international accord exists for researchersand clinicians regarding the best operational definition

of breastfeeding.6-8

This shortcoming is not because of lack of interest. Labbok and colleagues 6,9-10 have madecalls to researchers to define breastfeeding in uniformterms, and more recently, the Breastfeeding Committeefor Canada (BCC) 11 developed a Breastfeeding Defini-tions and Data Collection Periods guideline for use inCanada. This guideline defined 5 breastfeeding cate-gories, including exclusive breast milk and total breastmilk. Exclusive breast milk describes infants who havebeen fed no other foods or liquids besides breast milk since birth, and total breast milk describes infants who

Orig inal Research

Transitions in Breastfeeding: Daily Parent DiariesProvide Evidence of Behavior Over Time

Jennifer L. Bodnarchuk, PhD, Warren O. Eaton, PhD,and Patricia J. Martens, IBCLC, PhD

Abstract

This study addressed a key question for assessing breastfeeding duration: at what point is aninfant considered no longer exclusively breastfed or no longer breastfed at all? Mothers pro-vided longitudinal infant feeding data via daily checklists. Transitions between exclusive topartial breastfeeding and partial to no breastfeeding were compared across 11 time periods for10 age groups of infants. Daily transitions between exclusive and partial breastfeeding werecommon, especially for infants 6 months of age and younger, and transitions from partial tono breastfeeding occurred much more quickly than transitions from exclusive to partial breast-feeding. Ages at supplementation and weaning calculated in 1-day or 7-day spans correlatedhighly (intraclass correlation = .99). These results support the Breastfeeding Definitions andData Collection Periods guideline recently developed by the Breastfeeding Committee forCanada and may bring the breastfeeding research and clinical communities closer to a con-sensus on the definition of breastfeeding over time. J Hum Lact . 22(2):166-174

Keywords: exclusive breastfeeding, partial breastfeeding, longitudinal study, infant feedingtransitions, diary method

Received for review June 28, 2005; revised manuscript accepted for publi-cation October 2, 2005.

This research was funded by the Social Sciences and Humanities ResearchCouncil of Canada Research Grant 410-2001-0467 to Warren O. Eaton.

No reported competing interests.

Jennifer L. Bodnarchuk recently completed her PhD in DevelopmentalPsychology at the University of Manitoba, Winnipeg, Canada. Warren O.Eaton is a professor of Developmental Psychology at the University of

Manitoba and directed the 3-year longitudinal Milestones study on which thisresearch is based. Patricia J. Martens is the director and a senior researcherat the Manitoba Centre for Health Policy as well as an associate professorin the Department of Community Health Sciences, University of Manitoba.

The authors thank Linda Romphf, IBCLC, for her valuable help duringanalysis interpretation and manuscript preparation; Wendy Guenette, DenéeRyz, Amy De Jaeger, and Carolyn Barg for their vital assistance with theproject; and the families for their enthusiastic participation. Address corre-spondence and requests for reprints to Jennifer L. Bodnarchuk, PhD, e-mail:

[email protected].

J Hum Lact 22(2), 2006DOI: 10.1177/0890334406286992© Copyright 2006 International Lactation Consultant Association


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J Hum Lact 22(2), 2006 Transitions in Breastfeeding: Daily Parent Diaries 167

have been fed only breast milk in the past 7 days butwho received a temporary supplementation sometimesince birth.

Both the BCC’s guideline and the classification scheme

developed by Labbok and Krasovec6

are straightforward,yet Labbok and Krasovec’s original plea has notreceived widespread application, 9-10 and it is too early toknow whether the BCC guidelines are useful. Partof the difficulty in using these schemes may be that theyare designed for use at 1 point in time (eg, “the infantwas exclusively breastfed at 3 months of age”). 7 Use of these schemes over time is not appropriate because wecannot label a 2-year-old toddler as “exclusively breast-fed” when he or she was exclusively breastfed up to 4months of age. For the community of breastfeedingresearchers and clinicians to move closer to an agreed-

on operational definition of breastfeeding duration,more information is needed. The purpose of the currentstudy was to address 1 key question for such a defini-tion: at what point can we say that an infant is no longerexclusively breastfed or no longer breastfed at all?

At first, the answer may seem to be, for example, toask mothers to retrospectively provide the age at whichtheir infants were no longer breastfed or exclusivelybreastfed. 12 Although this seems simple enough at theoutset, once researchers consider that breastfeedingdoes not always follow a uniform progression fromexclusive to partial to none, 7,13-15 the picture becomesmore complicated. The reversible nature of feedingpatterns makes it difficult to define 1 point in timewhen exclusive or partial breastfeeding has ended.If the strictest definition of the duration of exclusivebreastfeeding were used, that is, exclusive breastfeed-ing ends the day any other liquid or solid is given, thenmost infants would not be exclusively breastfed beyondtheir hospital stay after delivery. 16-18 While such sup-plementation in the hospital may affect later breast-feeding and health and developmental outcomes, 16,18-21

a different definition that accounts for resumed exclu-sive breastfeeding would be useful for most researchers.

If mother-infant pairs can resume exclusive breast-feeding after partial breastfeeding for a given length of time, then how do we assign an end point to exclusivebreastfeeding? Perhaps after a certain duration of par-tial breastfeeding, the majority of mother-infant pairswill not return to exclusive breastfeeding, and theremay be a similar period for the transition from partialto no breastfeeding. It would be useful for breastfeed-ing researchers and clinicians to know whether such atransitional period is closer to a week or a month in

time. However, what that time span is, and how reli-able it may be, has not been addressed to our knowl-edge until now.

Methods Participants and Procedure

Mothers with young infants living in the city of Winnipeg and surrounding rural areas in Manitoba,Canada, were recruited from October 2001 to April2004 for a longitudinal study of infant gross motormilestone attainment. Recruitment efforts were targetedat mothers with infants younger than 8 months of age,and recruitment methods included brochures deliveredto mothers leaving a large maternity hospital with ahealthy newborn, an invited article in the community

section of the city newspaper, “Baby Welcome Wagon”visits to new mothers, and “word-of-mouth” solici-tations from friends and relatives. Each participantvoluntarily telephoned the project coordinator, and if the infant had not yet begun to walk (which was thefinal milestone of interest in the study), the coordinatormailed a package to the parent once the infant reacheda minimum age of 1 month. The package contained2 copies of a consent form, age-appropriate versionsof a daily checklist with corresponding instructions,a health and demographics questionnaire, and postage-paid envelopes. The daily checklists were designed

primarily to obtain information on motor milestones, 22but 4 of 36 checklist items were related to infant feed-ing: each day, the parent was asked to report whetherthe infant received any amount of breast milk, formula,cow milk, or other solids or liquids, including water.Parents returned completed checklists monthly.

All study procedures were performed in accord withthe Canadian Tri-Council Policy Statement on EthicalConduct for Research Involving Humans, which gov-erns research funded by the 3 major federal fundingagencies in Canada. The Research Ethics Board of theUniversity of Manitoba approved this study, and theparents gave written, informed consent.

Data Analysis

The checklists provided continuous daily informationon infant feeding, and although we had informationregarding formula, cow milk, and other solids and liq-uids, including water, we simply created 2 dichotomousvariables for each day: 1 for breastfeeds and 1 for allother feeds . Using these 2 variables, each day could beclassified as exclusive breastfeeding (breastfeeds but no




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168 Bodnarchuk et al J Hum Lact 22(2), 2006

other feeds), partial breastfeeding (both breastfeedsand other feeds), or no breastfeeding (other feeds butno breastfeeds). However, we did not stop at 1 day;instead, we considered consecutive days simultane-

ously. For example, we looked at a “window” of 3 daysand asked whether the infant could be deemed breast-fed for that 3-day span. We used window sizes from 1to 11 days to consider feeding patterns that lasted from1 day to more than one third of a month. 23 For windowsize 1, each day was a window. For window size 2,each window spanned 2 days, and the first window waschecklist days 1 and 2, the second window was days 3and 4, and so on. The same strategy was used for allother window sizes up to 11 days, in which the firstwindow was days 1 to 11, the second window was days12 to 22, and so forth. Windows were always assigned

starting with the first day of checklist completion, eventhough checklist completion started at different agesand continued for different lengths of time for differentinfants.

The categories of exclusive , partial , and no breastfeeding were applied to the various window sizes suchthat if any days within the window had breastfeeds andother feeds, the window was deemed partial . Forexample, if an infant were exclusively breastfed ondays 1, 2, and 3 and partially breastfed on day 4, thenthe corresponding 4-day window would be classifiedas partial . Thus, only 1 day with other feeds amongexclusively breastfed days led to a classification of

partial ; likewise, only 1 day with breastfeeds among amajority of other feeds was also classified as partial .The category of partial breastfeeding contained a rangeof feeding patterns, but exclusive breastfeeding alwaysmeant all days within the window had breastfeeds andno days had other feeds, and no breastfeeding alwaysmeant no days with breastfeeds and all days with otherfeeds, no matter what the window size.

The variation in partial breastfeeding was not a prob-lem in this study because our interest was to determinewhen mothers and infants transitioned between exclu-sive and partial or between partial and no breastfeeding.We expected some mother-infant pairs to go throughonly 1 transition in each category but other pairs to gothrough several transitions, for example, from exclusiveto partial, back to exclusive, and then back to partial.Our strategy of using differently sized windowsallowed us to see the variation in these kinds of flip-flopping transitions and whether, once the window sizewas large enough, the proportion of infants goingthrough such transitions approached zero.

To analyze the transitions, we counted 1 transitionfor every time a window was classified differently thanthe previous window. For example, a 3-window sequenceof exclusive-partial-exclusive feedings would be counted

as 2 transitions because the exclusive-to-partial shiftwould be 1 transition and the partial-to-exclusive shiftwould be a second transition. Because we did notexpect transitions to occur between exclusive and nobreastfeeding, we counted transitions during the startof supplementation (ie, exclusive to partial) separatelyfrom transitions during weaning (ie, partial to none).Furthermore, because infants at certain ages are morelikely than those at other ages to go through supple-menting and weaning transitions, we analyzed the databy age of infant—specifically, by counting transitionsin 1-month intervals. For example, for all infants in the

sample who had data between the end of their secondmonth of life and the end of their third month of life(ie, aged 2-3 months), we summed the number of tran-sitions occurring in that time span for each windowsize for each infant. This process was repeated for eachmonth of age. Because our data had been collectedacross different age spans for different infants, we useddata for a given month only when the infant had morethan 90% complete data for that month, and we allowedeach infant to be counted in as many age categories forwhich he or she had adequate data. Thus, sample sizesvaried by age of infant.

Because we expected that all exclusively breastfedinfants would transition from exclusive to partial andfrom partial to no breastfeeding at least once duringdevelopment and that partially breastfed infants wouldalso go through the latter transition at least once, wewere most interested in the percentage of infants whotransitioned 2 or more times during the start of supple-mentation and weaning. That is, we were interestedin the cases where the transition from 1 breastfeedingstatus to another was reversed.

After calculating the percentages of infants goingthrough transitions at different ages using differentwindow sizes, we chose 2 sizes (1-day and 7-daywindows) to compare the durations of breastfeedingassigned using each window size. For both sizes, thedate assigned for the duration of exclusive breast-feeding was the first day of the first window in whichpartial breastfeeding occurred. Duration of exclusivebreastfeeding was defined only for infants whose check-lists started with exclusive breastfeeding. The date forduration of any breastfeeding was assigned to the firstday of the first window in which no breastfeeding




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occurred, and duration of any breastfeeding was onlydefined for infants who were breastfed at the start of their checklists. The infant’s birth date was subtractedfrom these dates of duration to produce the infant’s ageof duration for exclusive and any breastfeeding. Forexample, if an infant who was born March 16, 2003,was first partially breastfed according to the checklistson July 28, 2003, then the age of exclusive breastfeed-ing duration would be 4.4 months.

All analyses were performed using SAS version 9.1(SAS Institute, Cary, NC). The values for the movingwindows were calculated using PROC EXPAND andother analyses used data set manipulations, PROCMEANS and PROC FREQ. For the transitions analyses,95% confidence intervals (95% CIs) were calculatedusing PROC MEANS, and for the duration analyses,intraclass correlations 24 were calculated using amacro by Dr Robert Hamer (http://www.psych.yorku.ca/lab/sas/intracc.htm). Intraclass correlations assess

the agreement between 2 measurements of the sameoutcome, and, unlike Pearson correlations, are loweredby mean-level differences; therefore, we used the intra-class correlations to determine the level of agreementbetween the 2 window sizes in assigning duration-of-breastfeeding values.

Results

In total, 603 mother-infant pairs enrolled during thestudy period. Of these, 427 (71%) submitted at least1 checklist, but 62 infants’ records were omitted becausethey had fewer than 30 continuous days of checklist data,leaving 365 (61%) infants with adequate data to conductthe analyses. Mothers ranged in age from 18 to 44 years( x - ± SD = 31 ± 5 years), and their education levels weresimilar to those of women aged 20 to 44 years in the cityof Winnipeg and the province of Manitoba (Table 1). 25

However, our sample had no mothers with less than ahigh school education and roughly twice as many moth-ers with a university education compared to the generalpopulation. Table 1 also shows that the sample familieshad a range of household incomes with a median that fellbetween Can$60 000 to Can$80000, which was higherthan the Winnipeg median of Can$43 385 and theManitoba median of Can$41661. 25 Male (n = 183; 50%)and female (n = 182; 50%) infants had similar birth andchecklist characteristics, and their data were analyzedtogether (Table 2).

Table 3 shows the percentage of infants whose tran-sition between exclusive and partial breastfeeding wasreversed. This matrix of percentages by infant age andwindow size shows that younger infants transitioned

Table 1. Distribution of Mothers’ Education and Household Income Levels

Current Sample Comparison Samples

n (%) City of Winnipeg, % Province of Manitoba, %

Mothers’ highest education levelLess than high school 0 (0.0) 16.7 21.4High school and/or some postsecondary 104 (28.5) 29.3 28.8Trade certificate or diploma 29 (8.0) 9.0 9.5College certificate or diploma 56 (15.3) 20.1 19.8University certificate, diploma, or degree 176 (48.2) 25.0 20.6

Annual household income< $20 000 25 (6.9)$20 000-$40 000 46 (12.6)$40 000-$60 000 71 (19.5)$60 000-$80 000 97 (26.6)> $80 000 102 (28.0)Not stated 24 (6.6)

Table 2. Characteristics of Infants

x - ± SD Range

Birth weight, g 3510 ± 520 1640 − 5130Birth length, cm 52 ± 3 43 − 61Gestational age, wk 39.8 ± 1.5 33.9 − 44.3No. of monthly checklists 8.0 ± 3.4 1 − 15

returnedPercentage of days 96.0 ± 8.9 49.7 − 100

completedAge at start of checklist 3.6 ± 2.3 1.0 − 12.3

completion, moAge at end of checklist 9.9 ± 3.4 2.5 − 17.8

completion, mo




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more often than did older infants and that more transi-tions occurred during shorter windows: the highestpercentages appear in the upper left of the matrix, anda block of zeros occupies the lower right. In general,day-to-day (ie, a 1-day window) patterns were themost variable: 28.8% (95% CI, 22.7%-34.8%) of 4- to5-month-old infants transitioned back and forth betweenexclusive and partial breastfeeding 2 or more timeswhen considered with 1-day windows, and 26.1%(95% CI, 18.0%-34.1%) of 2- to 3-month-old infantsdid so. That is, for example, after exclusive breastfeeding,they were partially breastfed for a day or more, and ona subsequent day, they returned to exclusive breastfeed-ing. After 4 continuous days (ie, window sizes 4-11)of partial breastfeeding, we know with 95% confi-dence that less than 5% of infants older than 5 months(ie, 5-6 to 11-12 months of age) transitioned back to exclusive breastfeeding. Conversely, Table 3 showsthat 16.8% (95% CI, 10.0%-23.6%) of 2- to 3-month-old infants continued to transition in spans of 4 days

(ie, a 4-day window) and that only after 8 or more days(ie, window sizes 8-11) did consistent adherence topartial breastfeeding approach 95% for the 2- to 3-monthage category.

Detailed exploration of data for the 2- to 3-month-oldinfants still transitioning after 8 or more days showed,for example, 1 mother who reported feeding her exclu-sively breastfed infant other foods, followed by 10 daysof exclusive breastfeeding, and after another short boutof feeding other foods, a return to exclusive breastfeed-ing for an additional 27 days. Other mothers showedsimilar patterns, with 18 and 23, 24 and 18, or 17 and15 days of exclusive breastfeeding during a transitionalperiod to partial breastfeeding. Of note is that the longersegments during these transitions were always of exclu-sive breastfeeding.

Transitions occurred much more quickly during wean-ing, as evidenced by the lower percentages in Table 4compared to Table 3. The low percentages mean thatmost infants went from partial to no breastfeeding and

Table 3. Supplementation: Percentage of Infants for Whom the Transition From Exclusive to Partial Breastfeeding Was Reversed, by Ageof Infant and Size of Moving Window

Window Size, d

Age of Infants, mo n 1 2 3 4 5 6 7 8 9 10 11

2-3 119 26.1 19.3 19.3 16.8 15.1 12.6 8.4 1.7 4.2 5.9 0.03-4 198 23.2 18.2 14.1 9.6 9.1 6.6 5.1 2.0 3.0 2.5 0.04-5 219 28.8 16.0 12.3 10.0 8.7 6.4 4.1 1.8 2.3 2.3 0.05-6 203 24.1 11.3 6.4 3.0 2.0 2.0 2.0 1.5 0.5 0.5 0.06-7 189 11.6 4.8 2.6 1.6 1.1 1.1 0.5 0.0 0.0 0.0 0.07-8 198 5.0 1.5 1.0 0.0 1.0 0.5 0.0 0.0 0.0 0.0 0.08-9 174 6.3 2.3 1.7 1.1 0.6 0.0 0.0 0.0 0.0 0.0 0.09-10 160 2.5 1.9 1.9 1.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0

10-11 146 2.7 2.1 1.4 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.011-12 111 3.6 0.9 0.9 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Table 4. Weaning: Percentage of Infants for Whom the Transition From Partial to No Breastfeeding Was Reversed, by Age of Infant and

Size of Moving WindowWindow Size, d

Age of Infants, mo n 1 2 3 4 5 6 7 8 9 10 11

2-3 119 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.03-4 198 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04-5 219 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.05-6 203 3.0 1.0 0.5 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.06-7 189 2.6 1.6 0.5 0.5 0.5 0.0 0.0 0.0 0.0 0.0 0.07-8 198 1.0 0.5 0.5 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.08-9 174 2.9 1.7 0.6 0.6 0.6 0.6 0.6 0.0 0.0 0.0 0.09-10 160 3.8 1.9 1.9 1.3 0.6 0.0 0.6 0.0 0.0 0.0 0.0

10-11 146 3.4 2.1 1.4 1.4 0.7 0.7 0.0 0.7 0.7 0.7 0.011-12 111 4.5 2.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0




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did not reverse the transition. For example, only 4.5%(95% CI, 0.6%-8.4%) of infants aged 11 to 12 monthsand 3.8% (95% CI, 0.8%-6.7%) of infants aged 9 to10 months transitioned back and forth between partialand no breastfeeding 2 or more times when consideredwith 1-day windows. After 5 days (ie, window sizes 5-11),hardly any infants in the current sample transitionedbetween partial and no breastfeeding in any age group.

We compared the ages at which first transitionsoccurred for infants who had adequate checklist datausing both 1- and 7-day windows. The black lines inFigure 1 show the percentage of infants in our subsam-ples (n = 145 for age at supplementation, n = 113 for ageat weaning) who were exclusively or partially breastfedto each age according to the 1-day window definition.The horizontal axis in the figure begins at 2 monthsbecause that was the youngest age for which dataexisted. The gray lines show the values for durationscalculated using the 7-day definition for the infants inthe same order that the infants were placed according tothe 1-day window definition. This allows a visual com-parison of the differences, by infant, between the dura-tions calculated using the 1-day and 7-day windows.

For the supplementation lines in Figure 1, the durationcalculated using the 7-day criterion was always within1 week of, and equal to or earlier than, the 1-day criterion.This occurred because in all cases, the day of partialbreastfeeding that counted for the exclusive-to-partial

breastfeeding transition using a 1-day window alsocounted for the exclusive-to-partial transition using the7-day window that contained that 1-day partial breast-feeding window. For example, if August 7 was the firstpartial breastfeeding day, then the 1-day window of August 7 marked the duration of exclusive breastfeeding,and the 7-day window starting as early as August 1(August 1-7) and as late as August 7 (August 7-13)also marked the duration of exclusive breastfeeding.Because we assigned duration to the first day of thewindow, the 7-day duration date would be betweenAugust 1 and August 7. The variation in the placementof the 7-day window around the corresponding 1-daywindow occurred because of the random nature of boththe starting date of checklist completion and the day of partial breastfeeding.

For the weaning lines in Figure 1, the duration cal-culated using the 7-day window was always equal to orlater than the 1-day criterion. This occurred because inall cases, the day of no breastfeeding that counted forthe partial-to-no breastfeeding transition using a 1-daywindow did not automatically count for the partial-to-no breastfeeding transition using the corresponding7-day window. The 7-day window required 7 days ina row of no breastfeeding. Thus, the durations usingeach window size were equal only when the 7-daywindow began on the day of the 1-day window and thenext 6 days had no breastfeeding. If the 7-day window

0

10

20

30

40

50

60

70

80

90

100

2 3 4 5 6 7 8 9 10 11 12 13 14 15Age of Infant in Months

P e r c e n

t o

f I n f a n

t s B r e a s

t f e d

Supplementation

Weaning

Figure 1. Supplementation and weaning using a 1-day and 7-day moving window: percentage of infants breastfed by age of infant inmonths. Black line = 1-day window; gray line = 7-day window.




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started earlier than the day of the 1-day window, thenthe 7-day window would have been a partial breast-feeding window and the transition would be counted asearly as the next 7-day window. In some cases (ie, the

horizontal “spikes” in the figure), 7 days in a row of nobreastfeeding did not occur until months after the firstno-breastfeeding day.

When we compared the age assigned by a 1-daywindow to that assigned by a 7-day window using anintraclass correlation, we found that the 2 values wereconsiderably correlated for both supplementation andweaning: the proportion of variance shared by the 2measurements was .99 for supplementation (n = 145)and .98 for weaning (n = 113).

Discussion

A proper research definition of breastfeeding overtime has been sought for several years 6-8; however, littleresearch has been done to show how various definitionsmay be useful in the context of real breastfeeding. Thisarticle begins to fill that gap by showing the variation inbreastfeeding transitions over time. By borrowing theidea of windows used in other research, 23 we were ableto investigate the limits of the time span over whichtransitions in breastfeeding usually occur. We concludedthat the time span varies by the age of the infant and thetype of transition (ie, exclusive to partial or partial to nobreastfeeding): infants younger than 5 months of agehave longer periods of transition between exclusive andpartial breastfeeding, with 16.8% of 2- to 3-month-oldinfants reversing breastfeeding patterns after 4 days ormore. In contrast to the variability seen between exclu-sive and partial breastfeeding, all infants transitionedrather quickly from partial to no breastfeeding.

Our results substantiate earlier suggestions that theonset of supplementation is harder to clearly definethan is weaning: Martens 7,26 reported that women faceddifficulty recalling when supplementation began, andQuandt 27 showed that fewer recall errors were madefor weaning than for supplementation. We found thatmothers indeed take longer to make a definite transitionbetween exclusive and partial breastfeeding comparedto the transition between partial and no breastfeeding.Thus, our data buttress Martens’ 7 earlier conclusion:when asked to recall when supplementation began,mothers may not struggle with faulty memory butrather with the problem of assigning 1 value to a processthat spans time. Further, mothers’ varied breastfeedingpatterns make it difficult to ensure that 2 methods for

determining the onset of supplementation or weaningwill lead to the same result or be interpretable in thesame way. Thus, researchers need to be especiallyclear in their definitions of infant feeding practices.

For the purposes of comparing 1-day and 7-daywindow definitions, we defined the duration of exclusivebreastfeeding as the time until the first day of the firstwindow where partial breastfeeding occurred and theduration of any breastfeeding as the time until the firstday of the first window where no breastfeeding occurred.However, there were certain limitations within this studyusing those definitions. A duration value could only beassigned for infants with data that included at least 1 rel-evant transition (eg, some infants were still breastfed atthe end of their final checklist). Further, we could notguarantee that the ages of duration that we assigned used

the true “first windows” because we did not have check-list data since birth for any infants. It was possible andeven likely that the infants who were exclusively breast-fed at the start of their checklist completion had not beenexclusively breastfed since birth. As well, it was possiblethat infants who were partially breastfed at the start of their checklist completion had not been breastfed everyday since birth. Thus, we could not be certain that ourdata produced accurate estimates of breastfeeding dura-tion. Furthermore, because not all infants in our samplestarted checklist completion at the same age or continuedfor the same number of months, and because using thewindows approach with our data did not provide dura-tion estimates for all infants, we could not determinethe overall percentage of infants who were breastfedeach month. Nonetheless, our available data did providea means of comparing the durations calculated usinga 1- or 7-day window.

Given the similarity between durations calculated using1-day and 7-day windows and the length of transitionalperiods, the 7-day approach used in the Canadian guide-line11 may better distinguish patterns of breastfeeding fora majority of infants compared to a single-day approach.For example, if a mother were asked whether she hadexclusively breastfed her infant on the previous day, anegative answer would not necessarily suggest that shehad completed the transition to partial breastfeeding.Indeed, a study of the effect of lactation counseling inGhana showed that the percentage of mothers whoreported exclusive breastfeeding in the past 24 hoursincreased for the intervention groups during the first6 months of their infants’lives. 28 Our results support thesechanging feeding patterns: more than 20% of infantsyounger than 6 months of age transitioned between





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exclusive and partial breastfeeding in 1-day spans.Conversely, if a mother were asked whether she hadexclusively breastfed her infant during the previousweek, a negative answer would provide more certainty,

but no guarantee, that she had transitioned to partialbreastfeeding. One caveat, as shown in the current study,is that for infants 5 months of age and younger, even a7-day span may not provide a high level of certaintybecause approximately 5% to 10% of infants at theseages continue to transition after 7 days. In addition, theGhana study of lactation counseling showed that thepercentage of mothers reporting exclusive breastfeedingincreased for the intervention groups during the first6 months of life, using intervals as long as 1 month.However, the increase must be interpreted within thecontext of the intervention, which was specifically

designed to increase exclusive breastfeeding rates.Notably, the control group mothers’ exclusive breast-feeding rates measured in 1-month intervals did notincrease after 2 months of infant age. 28

Seven days may be a conservative time span basedon the results for infants at all ages, but it has theadvantage of being an easy concept for people to grasp:our lives are structured around weeks of time, and younginfants’ages are often described with this metric. Thus,asking mothers to recall, for example, how old theirinfants were when they were first fed other foods atleast 1 day a week may be a successful strategy forassigning an appropriate value to the duration of exclu-sive breastfeeding. In the case of weaning, 7 days maybe highly conservative. However, as Figure 1 shows,durations measured by 1 day or by 7 days are relativelyclose for most infants, and either window size may beappropriate; that is, the precision of daily data collec-tion is not needed because weekly collection providesessentially the same information.

The substantial level of agreement between the2 window sizes does not preclude the existence of somesystematic bias. In fact, Figure 1 shows that for supple-mentation, the 7-day window consistently produced ayounger age than did the 1-day window, and for wean-ing, the 7-day window calculated a consistently olderestimate of the age of duration. However, this is partiallybecause of the specific calculations used in the presentstudy (eg, assigning the 7-day window date of durationto the first day of the window rather than the middle orlast day). Other strategies may have led to other calcula-tions and potentially other biases. For example, if we hadused the last day of the window, a bias in the oppositedirection would have occurred for supplementation.

In addition to the specific calculations in this study,other cautions for interpretation must be acknowledged.First, the study was based on a volunteer sample of Manitoba mothers, and although it is noteworthy that

the participants came from a range of socioeconomicbackgrounds, the median education and householdincome levels were higher than provincial averages.Second, completion of the daily checklists dependedon the mother’s motivation to continue completing andreturning the checklists. However, once mothers beganto complete the checklists, they found the task engag-ing and usually continued for several months. Third,because the checklists were focused on other aspectsof infant development, the items related to feedingneeded to be very brief; we did not collect informationon the amounts of various foods that the infant was

fed. Nonetheless, such additional information was notrequired for looking at transitions from exclusive topartial and partial to no breastfeeding because exclu-sive and no breastfeeding were defined in an all-or-none fashion. Fourth, because infants started checklistcompletion at different ages, we decided that the bestapproach was to analyze the results in 1-month agegroups. This notably limited the window size we coulduse. That is, as shown in Tables 3 and 4, no infantstransitioned 2 or more times using an 11-day window.This is an artifact of the 1-month span because onlytwo 11-day windows could be counted in a month,allowing for a maximum of 1 transition. Thus, wider agespans would have allowed longer transitional periodsto be assessed. Nonetheless, as the windows grew larger,fewer infants transitioned at these ranges. Finally, thesample size may be too small to draw general con-clusions, but it does provide a step toward a betterunderstanding of transitions in breastfeeding. Furtherresearch should use larger samples and investigateinfants younger than 2 months and older than 1 year of age as well as infants from a wider range of demographicbackgrounds.

In conclusion, this study is not a solution to theproblem of defining breastfeeding over time, but itmay provide a step in the right direction. The studydoes provide evidence that the Canadian 11 guidelinewill be a useful way to classify infants at 1 point intime. That is, defining categories of breastfeedingusing 7 days of information will likely correctly clas-sify more infants than will definitions considering only1 day. We hope that this study provides the impetus forfuture research to move closer to a consensus on thedefinition of breastfeeding over time.





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Resumen

Este estudio considera una pregunta clave de evalu-ación de la lactancia materna: hasta que punto se con-sidera que el bebe no recibe lactancia materna exclusivao no amamanta? Las madres dieron datos longitudinalesde la alimentación de sus hijos por medio de un diario

de actividades. Se compararon transiciones de lactanciaexclusiva a parcial y de parcial a no lactancia en 11períodos en 10 grupos etarios de bebes. Las transicionesdiarias de lactancia exclusiva a parcial fueron muycomunes, especialmente en los bebes de 6 meses omenores, y las transiciones de parcial a no lactanciaocurrieron mucho mas rápido que las transiciones delactancia exclusiva a parcial. Se correlacionaron fuerte-mente (correlación entre clases = .99) las edades desuplementación y cesación de la lactancia materna quese calcularon en períodos de 1 día y 7 días. Estos resul-tados apoyan las Definiciones de Lactancia Materna y la

Guía de Períodos de Recolección de Datos desarrolladarecientemente por el Comité de Lactancia Materna deCanadá y puede acercar más las comunidades de inves-tigación de lactancia y clínicas para llegar con el tiempoa un consenso en la definición de lactancia materna.


transitions in breastfeeding

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