Prospective cohort study

B - Click here for explanation of classification scheme.

POSITIVE: See Quality Criteria Checklist below.

To report the duration of breastfeeding among a population of Australian women and to identify factors that are associated with the duration of full breastfeeding to six months and any breastfeeding to 12 months.

• Women who delivered a live infant who was free of any serious health conditions that would require transfer to the NICU at Perth’s major maternity hospital
• Mothers whose infants were admitted to the special care nurseries of the participating hospital were eligible for recruitment.

This was not delineated.

Recruitment

587 women were recruited from two maternity hospitals in Perth and completed a baseline questionnaire just before or shortly after discharge from the hospital.

Design

Cohort study.

Statistical Analysis

• The chi-square test was used to compare the sociodemographic characteristics of participants and nonparticipants
• Survival analysis was used to examine the duration of any breastfeeding and full breastfeeding because it provided a good understanding of breastfeeding behavior over time
• Cox’s proportional hazards model was used to identify factors that were associated with the risk for discontinuing full breastfeeding before six months and any breastfeeding before 12 months.

Timing of Measurement

• Those who agreed to participate completed the self-administered baseline questionnaire while in the hospital  or shortly after discharge from the hospital
• Women were followed up by telephone interview at four, 10,16, 22, 32, 40 and 52 weeks postpartum.

Dependent Variables

• Fully breastfeeding for six months: An infant was considered to be fully or predominately breast fed when he or she received breast milk as the main source of nourishment, that is, with or without water, water-based drinks, fruit juice, or oral rehydration solution, but did not receive any other liquids (including breast milk substitutes) or solids
• Any breastfeeding to 12 months: Defined as an infant being fully breast fed or receiving both breast milk and formula, with or without solids.

Independent Variables

• Sociodemographic
  • Mother's age
  • Maternal education (years)
  • Mother’s country of birth
  • Marital status
  • Age of infant when mother returned to work
  • Biomedical
  • Parity
  • Method of delivery
  • Mother’s prepregnancy BMI
  • Mother smoked before pregnancy
  • Infant sex
  • Infant admitted to special care nursery (SCN)
  • Breastfeeding problem at four weeks or earlier
  • Age pacifier introduced.
• Hospital practices
  • Infant’s first feed [formula/other breast milk/colostrums(ref) 24-hour rooming-in in hospital]
  • Infant demand fed
  • Early infant-to-breast contact.
• Psychosocial
  • Intended pregnancy
  • Mother attended antenatal classes for this or previous pregnancy
  • Mother’s Iowa Infant Feeding Attitude Scale (IIFAS) score
  • Father prefers breastfeeding
  • Maternal grandmother prefers breastfeeding
  • Intended breastfeeding duration.

Control Variables

All of the independent variables explored, with the exception of intended duration, were entered into the multivariate models.

• Initial N: 587
• Attrition (final N): 382 at 12-month follow-up
• Ethnicity: Not specified
• Demographics: There were no significant differences in the age or level of education of participants compared with non-participants.

		N	Percentage
Maternal Age, Years		586
	<20	32	5.5
	20-24	122	20.8
	25-29	170	29.0
	30-34	178	30.4
	≥35	84	14.3
Maternal Education, Years		577
	<12	249	43.2
	≥12	328	56.8
Mother's Country of Birth		585
	Australia/New Zealand	428	73.2
	United Kingdom/Ireland	53	9.0
	Other	104	17.8
Parity		587
	Primiparous	216	36.8
	Multiparous	371	63.2
Method of Delivery		582
	Vaginal	411	70.6
	Cesarean	171	29.4

Location

Perth, Australia.

At six months of age, fewer than half (45.8%) of infants were receiving any breast milk (95% CI: 41.8-49.8), and only 12.0% (95% CI: 9.4 -14.6) were being fully breast fed. Fewer than 1% of infants were exclusively breast fed at six months of age. The median duration of full and exclusive breastfeeding was five and three weeks, respectively.

Infants who had been introduced to a pacifier at or before four weeks of age or experienced difficulties with breastfeeding at or before four weeks postpartum were less likely to be fully breast fed or receiving any breast milk at different time points.

The introduction of the pacifier before 10 weeks of age was significantly associated with a shorter duration of any or full breastfeeding.

Factors that Were Independently Associated with the Risk for Discontinuing Any Breastfeeding Before 12 Months and Full Breastfeeding Before Six Months (N=382)

Variablea		Fully Breastfeeding to Six Months		Any Breastfeeding to 12 Months
		HR	95% CI	HR	95% CI
Maternal Age, Years	<20	NS		0.57	0.23-1.41
	20-29			1.55	1.21-1.98
	≥30			1.00
Age of Infant when Mother Returned to Work	<6 months	1.42	1.08-1.88	1.69	1.28-2.34
	6-12 months	1.63	1.18-2.25	1.50	1.07-2.09
	Not working at 12 months	1.00		1.00
Breastfeeding Problems at or Before Four Weeks	Yes	1.75	1.35-2.23	1.64	1.29-2.10
	No	1.0		1.00
Age of Infant when Pacifier First Introduced	<4 weeks	1.92	1.39-2.64	1.92	1.40-2.64
	4-10 weeks	185	1.06-3.22	1.97	1.13-3.46
	>10 weeks	1.47	0.79-2.73	1.61	0.86-3.00
	Not using a pacifier at 12 months	1.00		1.00
Mother Smoked During Pregnancy	Yes	1.32	1.02-1.71	1.35	1.05-1.73
	No	1.00		1.00
Mother's Infant Feeding Attitude		0.97	0.96-0.99	0.96	0.94-0.98
Father's Feeding PreferenceMaternal Grandmother's Feeding Preferenceb	Prefers formula or ambivalent	1.00		NS
	Prefers breastfeeding	0.71		0.55-0.91
Maternal Grandmother's Feeding Preferenceb	Prefers formula or ambivalent	NS		1.00
	Prefers breastfeeding	0.71		0.55-0.2
Planned Pregnancy	Yes	0.76		0.60-0.98
	No	1.00		NS
-2 Log Likelihood (Deviance)		2,815.38, DF=10		2,880.62, DF=11

HR: Hazard ratio
NS: Not significant
DF: Segrees of freedom
^a All variables in the final model were variables for which, when excluded, the change in deviance compared with the corresponding chi-square test
^b As perceived by mother.

Variables in full models included maternal age, years of education, marital status, country of birth, parity, age of infant when mother returned to work, whether mother smoked during pregnancy, delivery method, whether the pregnancy was planned, whether mother roomed-in in hospital, demand fed or initiated breastfeeding within 30 minutes of birth, sex of the infant, whether infant was admitted to SCN, infant’s first feed, age of infant when pacifier first introduced, whether the mother attended antenatal classes, whether mother had experienced breastfeeding difficulty by four weeks postpartum, mother’s attitude about infant feeding, father’s feeding preference and maternal grandmother’s feeding preference.

 

Women should receive anticipatory guidance while still in the hospital on how to prevent or manage common breastfeeding difficulties and should be discouraged from introducing a pacifier before 10 weeks, if at all.

University/Hospital:

University of Manitoba (Canada)

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

Analytical longitudinal surveys refer to what epidemiologist term prospective or cohort studies. A cohort study is a study in which patients who presently have a certain condition and/or receive a particular treatment are followed over time and compared with another group 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 problem.

There was no description of how many women were lost to follow-up. Only 382 women (65% of the women participating in the study) remained for final analyses.