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BF: Artificial Nipple and Duration of Breastfeeding (2008)

Citation:

Mascarenhas MLW, Albernaz EP, daSilva MB, daSilveira RB. Prevalence of exclusive breastfeeding and its determiners in the first 3 months of life in the South of Brazil. J Pediatr (Rio J). 2006. 26: 82; 289-294.

PubMed ID: 16881009
 
Study Design:
Prospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

The objective of this study was to evaluate the prevalence of exclusive breastfeeding during the first three months of life of babies of the city of Pelotas, Brazil, and to identify factors that interfere with the practice.

Inclusion Criteria:
  • All infants born to mothers resident in the city of Pelotas, Brazil, were eligible for the study as long as they were free from contraindications against breastfeeding.
  • All mothers were informed about the research and signed a consent form. 

Exclusion Criteria:

Women with contraindication to breastfeeding

  • Mothers of newborn infants with severe malformations
  • Mothers who were seropositive for HIV.

 

Description of Study Protocol:

Recruitment

Randomly selected sample from all mothers whose children were born in the maternity units.

Design

Prospective cohort study.

Statistical Analysis 

  • The sample size was calculated based on a confidence interval of 95% and statistical power of 90% for exposure variables varying from 15% to 80%, with an estimated relative risk of 2.0. A further 15% was added to account for possible losses and to control for potential confounding factors.
  • For all analysis, the cutoff for statistical significance was set at P≤0.05.
  • For the multivariate analysis, all variables whose associations with the outcome had a P≤0.20 were selected to study possible confounding factors.
Data Collection Summary:

Timing of Measurements

  • This study utilized information from the perinatal phase and from the follow-up home visits at 90 days.
  • The research project was structured in two phases: Perinatal (hospital screening) and follow-up (home visits when babies were one, three and six months of age).
  • The perinatal phase consisted of interviews with all mothers whose children were born in the maternity units in the city of Pelotas between September 2002 and May 2003, with an estimated frequency of 400 births per month.
  • Follow-up visits were carried out between September 2002 and November 2003. The sample chosen for follow-up, approximately 30% of all mothers interviewed at maternity units, was selected by a means of a randomized list.

Dependent Variables 

The breastfeeding classification categories used in this study were the same as  those of the WHO/Pan American Health Organization (1991):

  • Exclusive breastfeeding: Children given just breast milk
  • Breastfeeding predominant: Children given  breast milk and  water, teas or juices
  • Breastfeeding: Children received any daily quantity of breast milk, irrespective of whether they were being given other foods
  • Partial breastfeeding: Children received breast milk plus some other type of milk
  • Weaned: Children ceased breastfeeding during the follow-up period.

Independent Variables 

Used the Hierarchical Model

  • Level 1:
    • Demographic: Baby’s sex, baby’s color, maternal age
    • Socioeconomic status: Family income, parents education
  • 2nd level
    • Mother’s characteristics, parity, smoking, type of delivery, number of prenatal consultations
    • Maternal employment, defined as whether mothers were employed during the month of the visit.
  • 3rd level
    • Babies' characteristics: Gestational age, birth weight
    • Pacifier use: Defined as whethert babies were being given pacifiers during the month of the visit.

Control Variables

For the multivariate analysis, all variables whose associations with the outcome had a P≤0.20 were selected to study possible confounding factors.

Description of Actual Data Sample:

Initial N: 973 mothers and their babies

Attrition (final N): 940

Age: 19% younger than 19 years old

Ethnicity:

 
Exclusive breastfeeding
 
Yes
No
 
N=364
%
N=576
%
Not white
99
27.2
152
26.4
White
265
72.8
424
73.6
 

Other relevant demographics:

 
Exclusive breastfeeding
 
Yes
No
 
N=364
%
N=576
%
Family income [(minimum wage(s)]
 
 
 
 
>6
61
16.8
55
9.5
3.1-6
82
22.5
109
18.9
1.1-3
156
42.9
287
49.8
≤ 1
65
17.9
125
21.7

Location: Pelotas, Brazil.

Summary of Results:

Results of the bivariate analysis of factors related to cessation of exclusive breastfeeding before three months of age showed that family income and maternal education demonstrated a dose-response effect, and pacifier use increased risk of these babies not being exclusively breastfed by 90%. 

Multivariate Analysis of Factors Associated with Cessation of Exclusive Breastfeeding before the Third Month of Life, by Hierarchical Model, Pelotas, RS, Brazil, 2003

Variable

OR(95% CI)*

adj OR(95% CI) ¥

Family income (MW) €

 

 

>6

1.00

1.00

3.1-6

1.47(0.93-2.34)

1.35(0.83-2.18)

1.1-3

2.04(1.35-3.08)

1.60(1.02-2.52)

≤1

2.13(1.33-3.42)

1.46(0.85-2.49)

Paternal education (years) €

 

 

≥9

1.00

1.00

5-8

1.41(1.05-1.90)

1.15(0.83-1.60)

0-4

2.10(1.40-3.16)

1.61(1.02-2.54)

Ignored

1.89(0.99-3.63)

1.57(0.80-3.10)

Maternal education (years) €

 

 

≥9

1.00

1.00

5-8

1.57(1.18-2.10)

1.26(0.91-1.73)

0-4

1.85(1.27-2.71)

1.31(0.84-2.05)

Maternal age (years) €

 

 

≥35

1.00

1.00

30-34

1.06(0.67-1.70)

1.10(0.68-1.77)

20-29

1.08(0.73-1.58)

1.08(0.73-1.61)

≤19

1.70(1.07-2.71)

1.53(0.95-2.47)

Smoking during pregnancy? §

 

 

No

1.00

1.00

Yes

1.50 (1.10-2.04)

1.37(0.99-1.90)

Maternity employment at 3 months? §

 

 

No

1.00

1.00

Yes

1.63(1.07-2.49)

1.76(1.15-2.71)

Number of prenatal consultations§

 

 

≥6

1.00

1.00

0-5

1.26-(0.91-1.75)

1.02(0.72-1.44)

Using pacifier at 3 months?†

 

 

No

1.00

1.00

Yes

4.25(3.19-5.66)

4.27(3.19-5.72)

MW=minimum wage(s)

* Unadjusted odds ratio with 95% confidence interval

¥ Adjusted odds ratio with 95% confidence Interval

€ Model 1: Family income, paternal education, maternal education and age

§ Model 2: Paternal education, smoking during pregnancy, maternal employment at three  

    months and number of prenatal consultations

† Model 3: Paternal education, smoking during pregnancy, maternal employment three   

   months and pacifier at three months.

Author Conclusion:
  • The results suggested that the practice of exclusive breastfeeding is still at levels much less than recommended, which in turn reinforces the need to continue stimulating breastfeeding during the first months of life.
  • This was a longitudinal population-based study that evaluated breastfeeding rates and factors associated with cessation of exclusive breastfeeding within the first three months of life.
  • 940 mothers of children age three months or younger were interviewed, 39% of whom were still exclusively breastfeeding and approximately one third of whom were no longer breastfeeding. Multivariate analysis by logistical regression demonstrated  a significant association between interruption of exclusive breastfeeding before three months and maternal employment, use of pacifier, low income (between one and three times the minimum wage), and less than five years‘ paternal education.
  • The factors of family income and maternal education demonstrated a dose-response effect, and pacifier use increased risk of these babies not being exclusively breast fed by 90%.
  • Babies given pacifiers had a four times greater risk of not being exclusively breast fed. There was a tendency (P=0.06) for mothers who smoked during pregnancy to breastfeed exclusively less.

Limitation

Because this study was part of a wider research project  that assessed several outcomes, it is limited by the fact that specific frequency data was not collected either for pacifier use or for supplementary foods.

Funding Source:
Reviewer Comments:

Analytical longitudinal surveys refer to what epidemiologists term prospective or cohort studies. A cohort study is a study in which patients who presently have a certain condition or receive a particular treatment are followed over time and compared with another group of subjects who are not affected by the condition under investigation. Studies of this kind provide a better opportunity than one-time cross-sectional studies to examine whether certain behaviors do in fact lead to (or cause) the disease.           

The limitations and critique of the study, as stated by the authors, seem appropriate.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? Yes
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? No
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes