Endocrine disruptors reduce breastfeeding

Diet and lifestyle 19. apr 2022 2 min Assistant Professor Amalie Timmermann Written by Kristian Sjøgren

New research shows that women’s exposure to chemicals such as bisphenol A and perfluoroalkyl substances have been associated with reducing the duration of breastfeeding. A researcher says that further research is required to understand how endocrine disruptors do this because breastfeeding is healthy for both the mother and the child.

The environment contains many substances that may be endocrine disruptors, affecting puberty, fertility or the immune system.

New research shows that some of these substances can also affect how long a mother breastfeeds her child.

According to the researchers behind the study, the result is useful because breastfeeding is essential for the baby’s development, including developing the child’s immune system. Breastfeeding also has many benefits for the mother, including reducing the risk of developing breast and ovarian cancer.

The research results also arrive at a time when more and more women report difficulty maintaining breastfeeding for as long as the Danish Health and Medicines Authority and other health authorities recommend.

“Women are vulnerable when they breastfeed, and many women find that they cannot produce enough milk to maintain breastfeeding. They want to breastfeed because it is important but cannot, and animal studies have shown that many substances in the environment can hormonally affect pregnancy and mammary gland development. This study showed that this also applies to people, with high levels of endocrine disruptors reducing the duration of breastfeeding,” explains a researcher behind the study, Amalie Timmermann, Assistant Professor, National Institute of Public Health, University of Southern Denmark, Copenhagen.

The research has been published in Environmental Research and the Journal of Clinical Endocrinology and Metabolism.

2,500 women participated

In the two studies, Amalie Timmermann and colleagues investigated whether having high concentrations of bisphenol A (BPA) or perfluoroalkyl substances (PFAS) in the blood or urine influences the duration of breastfeeding.

BPA is used in plastics and to coat the inside of cans, and PFAS have been used in everything from the textile industry to making Teflon®. There is international pressure to completely phase out the use of these substances.

The research was based on the Odense Child Cohort, in which researchers monitored 2,500 pregnant women and their children over several years.

During the study period, the women provided blood and urine samples and answered questionnaires about breastfeeding. The women recorded when they started feeding their children anything other than exclusively breast-milk, such as breast-milk substitute or porridge, and when they completely stopped breastfeeding.

The researchers linked the data on breastfeeding with the concentrations of PFAS and BPA in blood and urine provided by the women.

BPA slightly increases the risk of stopping breastfeeding

The researchers divided the women into three groups according to the concentrations of BPA in the urine samples.

High versus low concentrations of BPA were associated with discontinuing breastfeeding earlier, both 1) complete discontinuation and 2) partial discontinuation, including a transition to porridge or breast-milk substitute.

At each time point, women with the highest concentrations of BPA had a 7% higher risk of stopping breastfeeding than women with the lowest concentrations of BPA.

However, this result was not statistically significant.

“Thus, we cannot be sure that the apparent association actually exists. We found a slightly increased risk of early cessation of breastfeeding, but the result was not statistically significant and must therefore be reassessed in new research to confirm whether the association is real,” says Amalie Timmermann.

PFAS reduces the duration of breastfeeding

The researchers found a clear association for PFAS.

For each doubling of the concentration of PFAS in the blood (such as from 1 to 2 ng/mL), the risk of discontinuing breastfeeding increased by 20%.

The result was statistically significant and is in accordance with similar studies from the United States, Sweden, the Faroe Islands and other places.

“Overall, the conclusion is that some of the chemicals in our surroundings can affect a woman’s duration of breastfeeding,” explains Amalie Timmermann.

Major focus on environmental factors

Amalie Timmermann explains that, although the researchers found an association, it is too early to say for sure why women exposed to endocrine disruptors may stop breastfeeding sooner.

The researchers examined whether the endocrine disruptors affect the concentrations of prolactin, which stimulates milk production during and after pregnancy, but found no association.

“We do not yet know much about the underlying mechanisms, but the chemicals somehow affect the physiological functions that support breastfeeding, possibly by reducing milk production,” says Amalie Timmermann, who adds that she advocates more strongly focusing on the environmental factors that can affect the duration of breastfeeding.

“So we should not just tell women that breastfeeding for a long time is healthy for both themselves and their child. We as a society also need to protect them from the environmental factors that may reduce the duration,” concludes Amalie Timmermann.

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