A new mother's immune status depends on her breastfeeding strategy

“This is an excellent study. There are many unanswered questions about maternal health during the postpartum period,” said Amy Boddy, a human biologist and evolutionary theorist in the UCSB Department of Anthropology and lead author of the paper. Stated. This is a rare, in-depth look at immunity from the perspective of postpartum mothers, and she hopes this will serve as a springboard for future research.

In fact, much of the research on the effects of breastfeeding has focused on infants, she said, with many results showing the benefits of breastfeeding on infant immunity and development. In the long term, mothers who breastfeed also have a lower risk of developing certain cancers and diabetes.

But what about women in the critical first months and years after giving birth? For the study, Boddy, first author and co-principal investigator Carmen Hove, and their team followed 96 Seattle-area women who had given birth within the past six months, twice in 24 hours and once. Saliva was collected before birth. When I go to bed, and again when I wake up in the morning. With everyone in lockdown during the recent outbreak of the COVID-19 pandemic, researchers found that mothers' environments are more susceptible to infections that can confuse immune measurements. He found himself in an unexpectedly ideal situation: under strict control.

“This was kind of a perfect natural experiment, because we're looking at immune function, and the reports were that no one was getting sick,” Boddy said. the goal? It tracks the periodic levels of his five proteins (labeled CRP, IL-1β, IL-6, IL-8, and TNF-α) that indicate inflammation, which are markers of the immune response.

“Breastfeeding has long been shown to trigger a series of inflammatory responses,” Boddy explained. “Inflammation isn't necessarily a bad thing. Your breasts are rebuilding, functioning, and doing different things in your body.”The diurnal pattern of protein means that, generally speaking, concentrations are usually higher in the morning and in the evening. meant low. The researchers were interested in observing abnormal levels in the normal ebb and flow of these proteins and how they matched with new mothers' infant feeding strategies. .

For some proteins, there was no measurable deviation in morning and evening levels, regardless of whether the mother expressed or breastfed. However, for C-reactive protein (CRP), the researchers found that levels in women who relied heavily on breastfeeding peaked in the evening, reversing the normal diurnal trend.

“We expected that lower breastfeeding rates would be associated with a relatively higher morning peak in CRP, and vice versa,” Hove said. “What we ultimately found was that CRP was higher at night among mothers who reported intensive breastfeeding by breastfeeding or pumping.” This uniqueness in breastfeeding or lactating mothers Further research is needed to determine the exact impact of this pattern, she added.

“We don't know exactly what's going on here. Maybe it's not emptying the breast completely, which is causing the inflammation,” Boddy says. Or maybe it's the other way around, and inflammation is a healing response to pregnancy. Incomplete excretion may be a behavioral change due to stress. Perhaps the stress is a result of the sleep interruptions associated with the 24-hour feeding schedule. “There's no causal arrow to what's going on; it's just an association,” she says. “This study shows that there is a unique immune profile that needs to be studied further.”

What this study reveals is the true complexity of breastfeeding postpartum. Breastfeeding is part of an ongoing physiological negotiation between a mother and her new baby that gives the infant an advantage, Boddy said.

“There's something in evolutionary biology called maternal-fetal conflict, which is the idea that if you have two bodies in one mother's body, the baby will always want a little more than what the mother has to give. ” she explained. This study ventures into the gray area of ​​postnatal health from the mother's perspective, particularly in the areas of breastfeeding and immunity.

Indeed, despite the “breast is best” ideal long promoted by organizations such as the World Health Organization, researchers have found that even in a sample of educated, relatively affluent women, breastfeeding strategies during lactation The researchers discovered that a combination of these exists, highlighting the challenges of breastfeeding. Dedicated nipple feeding.

“There's been a lot of pushback, primarily from breastfeeding mothers, around time constraints. Our society doesn't make it easy to actually breastfeed and receive breastfeeding support,” she says. said Boddy, who raised both children at the time. “I'm challenged to meet my breastfeeding goals.” Additionally, the guidelines aren't clear about when breastfeeding should end. In this ongoing negotiation that could last for years, when will the physiological and other benefits for mothers diminish? Could this information provide some insight into other trends such as maternal mortality? Or?

The researchers hope to study this topic in greater depth and on a more individual level to uncover further patterns in postpartum health and breastfeeding, such as the different hormones involved in breastfeeding.

“I think this study reveals more questions than we answered. What we want to do is follow the postpartum experiences of these same women,” Boddy said. “Finding the best way to feed your baby is always difficult, and breastfeeding is extremely difficult.”