ORP: Postpartum Period (2014)


Carlsen EM, Kyhnaeb A, Renault KM, Cortes D, Michaelsen KF, Pryds O. Telephone-based support prolongs breastfeeding duration in obese women: A randomized trial.
Am J Clin Nutr. 2013 Nov; 98(5): 1,226-1,232.

PubMed ID: 24004897
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To evaluate whether telephone-based support could increase the duration of breastfeeding in obese women and, thereby reduce offspring growth.
Inclusion Criteria:
  • Consecutively recruited singleton, healthy infants born at term (more than 258 days of gestation) with a post-natal age of less than 48 hours
  • Women who intended to breastfeed and who had no history of breast surgery
  • Recruited between December 10, 2010 and June 30, 2012
  • All mothers had participated in the Treatment of Obese Pregnant study (TOP-study) at Hvidovre Hospital, Copenhagen University
  • The TOP study inclusion criterion was a pre-pregnancy BMI of 30 or higher, and the aim was to minimize weight gain during pregnancy (gestational weight gain, 5kg)
  • The current study was initiated one year and seven months after the TOP study had started inclusion and when 155 women had already completed the study period.
Exclusion Criteria:
Sick infants who required admission to a neonatal intensive care unit or who were suffering from congenital disease or malformations
Description of Study Protocol:


We consecutively recruited singleton, healthy infants born at term (more than 258 day of gestation) with a post-natal age of 48 hours or less.Participants were recruited between December 10, 2010 and June 30, 2012. All mothers had participated in the Treatment of Obese Pregnant study (TOP study) at Hvidovre Hospital, Copenhagen University. 



  • The breastfeeding promotion was designed as a telephone-based advisory support service, and was performed by a certified lactation consultation
  • All contacts followed a structured design posing questions of physical and psychological aspects related to breastfeeding and the well-being of the mother and child
  • It was determined whether the mother had sufficient knowledge of breastfeeding; advice was provided if necessary
  • Any difficulties were discussed; possible solutions were identified
  • It was registered whether breastfeeding was exclusive or partial
  • The termination of breastfeeding was registered, as well as the date of the introduction of other nutritional supplements apart from vitamin D, an iron supplement and water
  • The first contact was set to last 20 minutes, whereas the duration of the following calls was between five and 10 minutes
  • The initial contact was made within the first week
  • All participants were offered a minimum of nine consultations during the first six months, provided that the mothers breastfed during the entire period
  • Three contacts were made during the first month; thereafter participants were contacted every second week until eight weeks postpartum and thereafter once monthly
  • Extra contacts were offered for specific difficulties, whereas support was stopped when breastfeeding was terminated
  • All women had the direct telephone number to the lactation consultant, who was available seven days a week
  • Breastfeeding data were collected by telephone
  • At the age of six months, all infants underwent a clinical examination
  • Exclusive breastfeeding was defined according to the WHO criteria of breastfeeding, and supplemented with vitamin and mineral supplements and water
  • Partial breastfeeding was defined as breastfeeding supplemented with formula milk or solid food.

Statistical Analysis

  • Descriptive statistics, means and SD were calculated for all outcome variables. These variables were compared between telephone support and standard care to disclose any differences in maternal and infant variables. For normally distributed data, independent student T-tests were calculated. The Mann-Whitney U-test was used to compare medians for non-normally distributed data. Fisher’s exact and chi-square tests were used to analyze any differences between proportions. Binary logistic regression was used to calculate crude and adjusted OR and 95% CI for breastfeeding in relation to random assignment at three days, seven days, four weeks and three months after birth:
    • For exclusive breastfeeding
    • At six months after birth for partial breastfeeding.
  • A Kaplan-Meier plot was made to illustrate the time to cessation of both exclusive and any breastfeeding by comparing the intervention group to controls. Cox regression was used to statistically test the duration of exclusive and any breastfeeding in the intervention group compared with the control group. If the woman was still breastfeeding at six months, the case was censored, meaning that no event occurred. An event was defined as the cessation of exclusive or any breastfeeding.
  • The telephone-support group was compared with the standard care group by using an independent student T-test. 
Data Collection Summary:

Timing of Measurements

Random collection at:

  • Three days, seven days, four weeks and three months after birth for exclusive breastfeeding
  • At six months after birth for partial breastfeeding.

Dependent Variables

Length of breastfeeding duration.

Independent Variables

Telephone support.


Description of Actual Data Sample:
  • Initial N:
    • Supported: N=105 of 108
    • Control: N=102 of 118.
  • Attrition (final N): 
    • Supported: N=105
    • Control: N=102.
  • Age:
    • Support: 31.3±4.5 years
    • Control: 31.8±4.1 years.
  • Ethnicity: Danish
  • Anthropometrics: Pre-pregnancy BMI: 32.5 (30.0 to 50.3) vs. 32.8 (30.0 to 45.6)
  • Location: Hvidovre Hospital, University of Copenhagen, Copenhagen, Denmark.


Summary of Results:

Key Findings

  • There were no differences in baseline characteristics regarding maternal and infant data between the two groups
  • Women in the support group received a mean of 6.9±6 2.5 telephone calls (median: eight calls; range: one to nine calls)
  • Extra calls were given in 37 cases (1.6±0.87 calls; median one call; range: one to four calls)
  • Only five persons contacted the lactation consultant (one time by three subjects; two times by two subjects)
  • Women in the intervention group maintained exclusive breastfeeding for a median of 79 days (P=0.003) and any breastfeeding for a median of 76 days (P=0.002) longer than did control subjects
  • Courses of exclusive and any breastfeeding in the two groups are show an overall improved breastfeeding rate in the intervention group for both exclusive (P=0.032) and partial breastfeeding (P=0.02)
  • The support group had significantly higher exclusive and partial breastfeeding rates
  • There was no effect of TOP study random assignment (diet and exercise) on the duration of exclusive breastfeeding (P=0.84) or partial breastfeeding (P=0.59).

Other Findings

Wording from the abstract (adds OR): 

  • The support group breastfed exclusively for a median of 120 days (25th to 75th percentiles: 14 to 142 days) compared with 41 days (three to 133 days) for control subjects (P=0.003). Any breastfeeding was maintained for a median of 184 days (92 to 185 days) for the support group compared with 108 days (16 to 185 days) for control subjects (P=0.002).
  • Support increased the adjusted OR for exclusive breastfeeding at three months and the ratios for partial breastfeeding at six months to 2.45 (95% CI: 1.36, 4.41; P=0.003) and 2.25 (95% CI: 1.24, 4.08; P=0.008, respectively). 
Author Conclusion:
A telephone-based intervention by a lactation consultant prolongs exclusive and partial breastfeeding in obese women during the first six months postpartum. 
Funding Source:
Reviewer Comments:
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) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  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? N/A
  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? Yes
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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.) No
  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? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  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? Yes
  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? N/A
  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)? N/A
  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? Yes
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