Scheduled or on-demand feeding? Effects on children’s educational outcomes, psycho-social...

Scheduled or on-demand feeding? Effects on children’s educational

outcomes, psycho-social development

and sleeping patternsMaria Iacovou

University of CambridgeUNICEF UK Baby Friendly Initiative Conference

Glasgow, 27th-28th November 2013

What we know already

what you feed a baby

when you feed a baby

Questions

Do feeding schedules affect babies’ and children’s development?

Growth and health?Cognitive development?Psycho-social adjustment?Later sleeping patterns?And mothers’ wellbeing?

Data: ALSPAC

Avon Longitudinal Study of Parents and Children

About 10,500 babies born in 1990 and 1991

Based in and around Bristol

Information from:Both parents, 3x during pregnancy Both parents, repeatedly over childhoodWeights, measures and various testsTeacher assessmentsData from national tests

Variable of interest: feeding schedules

Asked at 4 weeks:

“Is your baby fed (either by breast or bottle) on a regular schedule (e.g. every 4 hours)?”

“Yes, always” (7.2%)

“Try to” (23.4%)

“No, fed on demand” (69.4%).

1. Maternal wellbeing

“Getting enough sleep?”

“Feeling: weepy or tearful? irritable? exhausted?”

Maternal confidence and enjoyment scales

“Motherhood is something a woman learns naturally”

“...Pretty sure I’m doing the right thing for my child”.

Depression measures: Edinburgh & Crown-Crisp scales.

Continuous variables are standardised; discrete variables are collapsed into two categories.

2. Cognitive attainment

SATs scores in Reception class (age 5), KS1 (age 7), KS2 (age 11) and KS3 (age 14)

Ages 5 and 7: Reading, writing, maths

Ages 11 and 14: English, maths, science

Separate IQ test at age 8

All standardised (0,1)

Strengths & Difficulties questionnaire

Teacher assessments in Years 3 & 6 (ages 8 & 11)

Five domainsHyperactivityEmotional problemsPeer problemsConduct problemsProsocial score

Aggregate composed of the 4 “problem” scores

3. Psycho-social outcomes

6 months, 18 months, 9 years: does child sleep regularly?

9 years: Refusing to go to bed, difficulty falling asleep, night waking, early morning waking, nightmares.

9 and 11 years: sleep durations

4. Sleeping

Mothers and babies randomly assigned to scheduling or demand groups

Unfortunately, no such trial exists

Feeding mode is a choice mothers make, based on various factors....

... which may also affect their babies’ development

Use statistical techniques which account for this selection

The ideal: a randomised controlled trial

Who feeds to a schedule?

Demand-feeding mothers in the sample are from more socially privileged groups. For example:

6% of schedule-feeding mothers have a degree

8% of “tried a schedule” mothers

18% of demand-feeding mothers

“Tried-a-schedule” mothers are much more similar to schedule-feeding mothers than to demand-feeding mothers.

Analytical methods

Ordinary Least Squares and logistic regressionControl for factors including social class, education, marital situation, mother’s work, health behaviours, housing, breastfeeding, etc etc

Propensity Score MatchingCompare “like with like”Compare schedule-feeding mother-baby pairs with demand-feeding pairs who look just like them

Results: maternal wellbeing

On almost all measures, schedule-feeding mothers report significantly higher levels of wellbeing than demand-feeding mothers.

These differences persist for at least 3 years

However, on the formal measures of depression, there is NO difference between the two groups

Mothers who tried to schedule have the same outcomes as demand-feeding mothers.

0

20

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Maternal confidence,

8m

Maternal confidence,

33m

Maternal enjoyment,

8m

Maternal enjoyment,

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Incr

ease

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ater

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Demand

Tried

Schedule

Results: cognitive development

After controlling for observable differences between the samples, demand-fed babies do significantly better than schedule-fed babies on all SATs tests and IQ tests.

The outcomes of “tried-a-schedule” babies are no different to those of demand-fed babiesIacovou, M. and Sevilla-Sanz, A (2013). "Infant feeding: the effects of scheduled vs. on-demand feeding on mothers' wellbeing and children's cognitive development" European Journal of Public Health (2013) 23(1) pp 13-19

Questions:

How big is the effect? About 17% of a standard deviationConservative estimate: about 3 “positions” in a class of 30 children

What might be the mechanisms? Discuss this later

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Cognitive attainment

A question on breastfeeding

Could the relationship between demand feeding and better cognitive outcomes arise because of longer breastfeeding durations for demand-feeding mothers?

Answer: yes, but only partially

(about 2 points of the 17-point difference comes via breastfeeding durations)

Perhaps the most important question of all

We’ve controlled for observable differences between mothers. But what if unobservable differences are driving the relationship between feeding mode and children’s outcomes?

Two reasons why this probably isn’t a major issue.

First, the outcomes of “tried-to-schedule” babies.Second, look at this graph...

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Science, KS3

English, KS3

Maths, KS2

Is unobserved heterogeneity driving the effect?

Results: psycho-social adjustment

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.1

.15

.2

-5 0 5 10 15 sdqY6tot

kernel = epanechnikov, bandwidth = 1.2000

Kernel density estimate Year 6 SDQ scores,

by sex

Results: psycho-social adjustment

Results differ by gender

For boys: no difference in outcomes between schedule- and demand-fed children.

For girls: significant differences in outcomes, with demand-fed babies having a lower incidence of later problems.

Effects are concentrated in the hyperactivity and emotional components of SDQ

Results: sleeping habits

Question: do schedule-fed babies have better/different sleep habits than demand-fed babies?Answer: not reallySchedule-fed babies are more likely to sleep regularly at 6 monthsBut not at older agesAt age 9, schedule-fed babies more likely to refuse to go to bed and to wake at nightBut differences are really very small

Results: sleep durations

9 years 11 years

Schedule 11.25 10.97

Tried 11.06 10.78

Demand 10.91 10.60

Schedule-fed babies: 20 mins longer sleep durations

Fairly large difference: 0.5 SD

0.1

.2.3

.4D

ensi

ty

6 8 10 12 14sleep9_SD

kernel = epanechnikov, bandwidth = 0.8000

Kernel density estimate

School-day sleep durations, age 9

by feeding mode

demand

schedule

Implications

Robust relationship

Possible issues with parental reporting

Next step: get hold of data on ALSPAC subsample who were “metered”

Assess whether 20 mins extra sleep is a good thing

What are the mechanisms?

Heterogeneity between mothers

Possible, but unlikely to be a major factor

Heterogeneity between babies

Possible: investigate with observational studies

Possible causal mechanisms

Breastfeeding durationBiological – frequency of feeding affecting concentration of lipids in milk? Demand-feeding encourages interactive “asking-and-getting”?Maternal responsiveness

Next steps

Collaborate with psychologists to measure effects of feeding mode on (eg) stress hormones Collect more detailed data on the nature of feeding schedules (and demand feeding)More work on sleep!

Scheduled or on-demand feeding? Effects on children’s educational outcomes, psycho-social...

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