Data on 85,000 individuals show that how long and how intensely a child breastfeeds are associated with more completed education and greater future income for the child. A researcher says that this is important knowledge for the health authorities that prepare guidelines for breastfeeding.
A new study in which researchers reviewed data on almost 85,000 individuals followed for more than 50 years concludes that longer and more intense breastfeeding is associated with greater educational attainment and future income for the children.
The study shows that individuals who breastfeed for the longest time complete more years of education, are less often outside the labour market and have higher lifetime income.
According to a researcher behind the study, the results should not be used to stigmatise mothers who breastfeed their children for a short period or who do not breastfeed their child exclusively. However, health authorities can use the results when preparing guidelines and in allocating resources to postnatal care and visits by public health nurses.
“Previous studies have shown that prolonged breastfeeding is associated with higher intelligence. We aimed to investigate whether this higher average intelligence also translates into more years of completed education and ultimately higher income. Our results confirm this, which may be an important factor when health authorities and public health nurses advise mothers on breastfeeding,” explains Lise Geisler Bjerregaard, Senior Researcher, Section for Epidemiology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark.
The research has been in published in Public Health.
Duration of breastfeeding linked to educational attainment and income
The researchers investigated the importance of the duration and intensity of breastfeeding by examining the Copenhagen Infant Health Nurse Records for individuals born between 1959 and 1967.
These records have been digitised and contain information on breastfeeding that nurses recorded at eight time points during the child’s first year of life.
The researchers divided the 84,255 children according to breastfeeding for <1 month, 1–5 months and >5 months and fully or partly breastfeeding.
The researchers also obtained data on the mothers’ educational attainment, since this is also associated with the children’s educational attainment and later income.
The researchers used Denmark’s registries to identify the children up to the age of 50 years and determine their educational attainment and income.
They divided the children according to the duration of breastfeeding and the mother’s years of education.
“Remember that the options for breastfeeding a child differed in the 1950s and 1960s. If a woman was employed, she might not be able to breastfeed, and it was not fashionable at the time. Today, conditions are better, at least in Denmark, but women in many other countries still do not have good conditions to breastfeed their child for a long period,” says Lise Geisler Bjerregaard.
Great differences between longer and shorter breastfeeding
The results show strong associations between breastfeeding and the duration of education, the probability of completing a long degree programme and lifetime income.
For the children of mothers with low educational attainment, breastfeeding for >5 months versus <1 month meant that they earned nearly DKK 28,000 more per year on average than the average person 25–50 years old (in 2015 Danish kroner, 10% higher income).
For the children of mothers with high educational attainment, this difference was only around DKK 13,000 per year.
Similarly, breastfeeding was also associated with the child’s educational attainment. The children breastfeeding for >5 months (regardless of the mother’s educational attainment) completed about seven months more of education than the children breastfeeding for <1 month.
The children of mothers with low educational attainment and breastfeeding for >5 months were 46% more likely to complete a long degree programme than children breastfeeding for <1 month. The numbers from this comparison were 28% for the children of mothers with medium educational attainment and 16% for the children of mothers with high educational attainment.
Further, the researchers found that children breastfeeding for >5 months had a 23% lower risk of being outside the labour market by the age of 50 years.
Finally, the researchers found a dose–response relationship: longer and more intensive breastfeeding led to both more education, higher income and less risk of being outside the labour market.
“I think these numbers are remarkable, because the differences associated with short and long breastfeeding are so large despite the durations in our population being relatively short,” explains Lise Geisler Bjerregaard.
Also important for health and disease
According to Lise Geisler Bjerregaard, breastfeeding has many advantages, and she encourages mothers to breastfeed their children and follow the recommendations to breastfeed for at least six months.
However, she also points out that women who are not able to breastfeed or choose not to should not be stigmatised but supported in their feeding choices. Many other factors than breastfeeding influence both educational attainment and income.
The results should therefore primarily inform health authorities about the benefits of whether women breastfeed their children for a short or long time.
“Our next study will examine the potential lifelong effects on health of short versus long breastfeeding. Considerable research is investigating the importance of breastfeeding and why breast-milk is so healthy and conducive to cognition. Breastfeeding reduces the risk of disease and mortality, which can be especially important in low-income countries with high infant mortality. Further, studies of breast-milk have indicated that long-chain polyunsaturated fatty acids are one possible explanation that breastfeeding boosts cognition,” concludes Lise Geisler Bjerregaard.
