Breastfeeding has been in question forever when should you stop? How long should you do it for? What are the short-term and long-term benefits? I found a couple of studies that look at the duration of breastfeeding and the correlation of intelligence quotient (IQ), income at the age of 30 years old, and years of schooling.
This study by Cesar Victora used information about breastfeeding in early childhood, then at age of 30, they studied the IQ, education attainment, and income of participants. Then using multiple linear regression with adjustment for 10 confounding variables to look for correlations. The results show that the identified dose response that was associated highest with the increased IQ level was 12 months or more had higher IQ scores, more years of education, and an increase in monthly income (Victora 2015).
Other studies looked at how there was a positive correlation between the duration that a child was breastfed and the performance in secondary school test scores (Horwood 1998). Another study reported that breastfeeding also had a positive correlation with blood pressure and body mass index as well as a higher IQ (Brion 2011).
Now breastmilk (BM) is very important for the growth and maturation of the organs, especially for infants. BM has macro and micronutrients for infants to develop. An important part of BM includes antioxidants, to counteract the negative effects of oxidative stress in babies (Yuksel 2015). These antioxidant compounds include alpha-carotene, beta-carotene, lycopene, retinol, alpha-tocopherol, and y-tocopherol (Yuksel 2015). Overall breastmilk encourages neuronal growth factors to increase brain development (Yuksel 2015). Also increases vascular Endothelial growth factors to help all of the organs and tissues grow and develop (Yuksel 2015).
The more the baby develops in a normal way the most natural way, the brain can develop with the most nutrients possible which could be the link to an increase in IQ score. However, this is a hard claim to prove, because no matter how alike each participant is, there is always a possibility of environmental factors affecting the IQ scores.
Brion, M. J., Lawlor, D. A., Matijasevich, A., Horta, B., Anselmi, L., Araújo, C. L., Menezes, A. M., Victora, C. G., & Smith, G. D. (2011). What are the causal effects of breastfeeding on IQ, obesity and blood pressure? Evidence from comparing high-income with middle-income cohorts. International journal of epidemiology, 40(3), 670–680. https://doi.org/10.1093/ije/dyr020
Horwood, L. J., & Fergusson, D. M. (1998). Breastfeeding and later cognitive and academic outcomes. Pediatrics, 101(1), E9. https://doi.org/10.1542/peds.101.1.e9
Victora, C. G., Horta, B. L., Loret de Mola, C., Quevedo, L., Pinheiro, R. T., Gigante, D. P., Gonçalves, H., & Barros, F. C. (2015). Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil. The Lancet. Global health, 3(4), e199–e205. https://doi.org/10.1016/S2214-109X(15)70002-1
Yuksel S., Yigit A.A., Cinar M., Atmaca N., Onaran Y. Oxidant and Antioxidant Status of Human Breast Milk During Lactation Period. Dairy Sci. Technol. 2015;95:295–302. doi: 10.1007/s13594-015-0211-z.
This is an interesting topic Madi! I think many people who are breastfeeding or might breastfeed one day are curious about this question. It is also a very taboo topic, especially to discuss or witness in the public, but ironically gets a lot of public opinion. Many mothers get shamed for breastfeeding too long or too short, and/or for breastfeeding in public. I found a longitudinal study that followed a cohort of babies born after 37 weeks gestation and measured their cognitive development at 3, 5, 7, & 11 years of age (Pereyra-Elías, 2022). However, while the results showed that babies breastfeed for >12 months had higher cognitive development compared to babies not breastfeed at all, the researchers discussed many confounding variables that made this data difficult to interpret (Pereyra-Elías, 2022). Possible confounding variables are parental relationship, cesarean section, alcohol and tobacco use during pregnancy, and many others (Pereyra-Elías, 2022). This is a tough subject to research since there are many confounding variables which makes it also very easy for the public to form opinions on it because there is not an exact answer.
ReplyDeletePereyra-Elías, R., Quigley, M. A., & Carson, C. (2022). To what extent does confounding explain the association between breastfeeding duration and cognitive development up to age 14? findings from the UK millennium cohort study. PLoS One, 17(5) doi:https://doi.org/10.1371/journal.pone.0267326