Breast pumps may introduce harmful bacteria to babies’ gut microbiome

Using a breast pump may introduce babies to the “wrong” kind of bacteria, and perhaps increase their risk of childhood asthma.

Shirin Moossavi at the University of Manitoba, Canada, and colleagues found milk from pumps contained higher levels of potentially harmful microbes than milk straight from the breast.

“Increased exposure to potential pathogens in breast milk could pose a risk of respiratory infection in the infant,” says Moossavi. This might explain why infants fed pumped milk are at increased risk for paediatric asthma compared with those fed exclusively at the breast, she says.

Exactly how bacteria become established in the infant gut is unclear. Microbes from the mother carried in breast milk is one probable route, but so is the transfer of mouth bacteria from the mouth of a sucking baby.

Breast pumps offer a third, artificial pathway – one that can potentially transmit a range of environmental bacteria to the baby.

Harmful pathogens

For the study, the researchers looked for bacterial genes in breast milk samples from 393 healthy mothers three to four months after giving birth.

The team found the bacterial content of milk being fed to the mothers’ babies differed greatly from infant to infant.

Milk administered from breast pumps contained higher levels of potentially harmful “opportunistic pathogens”, such as those from the genus Stenotrophomonas and family Pseudomonadaceae.

In contrast, direct breastfeeding without a pump was associated with microbes typically found in the mouth, as well as greater bacterial richness and diversity. This suggests infant mouth microbes play an important role in determining what kind of bacteria are found in mothers’ milk.

“This study considerably expands our understanding of the human milk microbiota and the factors that might influence it,” says study co-author Meghan Azad at the Children’s Hospital Research Institute of Manitoba. “The results will inspire new research about breastfeeding and human milk, especially related to pumping.”

By New Scientist Staff and Press Association