Breastfeeding, Prolactin, and Rheumatoid Arthritis

Among other benefits, breastfeeding has been linked to decreases in a child's future risk of obesity and cardiovascular disease, but what medical benefits might there be for the mother? A study in the November edition of Arthritis & Rheumatism reports the longer a mother breastfeeds her child, the less likely she will develop Rheumatoid Arthritis (RA) later in life. How this bears on the fact that women suffer from inflammatory diseases at a greater rate than men has yet to be concluded.

According to the multi-site study, (at Brigham and Women's Hospital in Boston and the Hospital for Special Surgery in New York City) breastfeeding was "inversely related to the development of RA." Specifically, women who breastfed their children for at least 12 cumulative months saw their risk of RA reduced by twenty percent; women who breastfed their children for a cumulative 24 months saw their risk of RA cut in half. Based on twenty-six years (1976-2002) of research and a patient sample of 121,700 women, the findings certainly carry weight.

But because of the study's length, breadth and, mostly, its conclusion, it very well may have opened a new chapter in the story of women and RA. Citing the gender imbalance in inflammatory diseases, it was general medical consensus that breastfeeding would increase a woman's chance of RA. One study notes, "breast-feeding appears to increase the risk of RA, possibly through the actions of the lactation hormone prolactin" and another writes, "breastfeeding and hyperprolactinemia constitute a risk for...RA." In fact, when the breastfeeding study began, the researchers expected a reaffirmation of the correlative link between breastfeeding and RA, but as they later wrote, "our findings demonstrated the opposite."

At question is the role of prolactin, the lactation hormone mentioned earlier; secreted from the pituitary gland, the hormone is also responsible for the body's maturation process and the regulation of the immune system (whereas RA appears to trigger hyperinflammation within the immune system.)

Past studies have shown elevated prolactin levels in RA patients but these studies admit struggling to explain the relationship between the prolactin hormone and RA--is it a causative link or a correlative link? For instance, one study, using 23 RA patients and 8 control subjects (all of whom were post menopausal women), observed higher prolactin levels in the RA patients and concluded that RA could involve a "dysregulation" in the pituitary gland. For sure, a pituitary malfunction could involve other factors beyond prolactin. Using 49 RA patients and 16 healthy controls, another study also found elevated prolactin levels in the RA patients. And while some RA patients had higher prolactin levels than others, this still didn't make a difference in the patient's clinical condition.

Researchers from the breastfeeding study plan to examine the hormone levels from blood samples taken in 1989. Using their findings, hopefully they can shed new light on the workings of an important, but unclear link to RA.

Article References
E. Karlson , L. Mandl , S. Hankinson , F. Grodstein. Do breast-feeding and other reproductive factors influence future risk of rheumatoid arthritis?: Results from the Nurses' Health Study. Arthritis & Rheumatism. Volume 50, Issue 11, Pages 3458-3467.

NJ Olsen, WJ Kovacs. Hormones, pregnancy and rheumatoid arthritis. J Gend Specif Med. 2002 Jul-Aug; 5(4): 28-37 & M Neidhart, RE Gay, S Gay. Prolactin and prolactin-like polypeptides in rheumatoid arthritis. Biomed Pharmcother. 1999 Jun; 53 (5-6): 218-22.

C Jorgensen, H Maziad, C Bologna. Kinetics of prolactin release in rheumatoid arthritis. Clin Exp Rheumatol. 1995 Nov-Dec; 13 (6): 705-9.

J. Rovensky, J. Baskova, J. Payer et al. "Increased demand for steroid therapy in hyperprolactinemic patients with Rhematoid Arthritis." Int J Tissue React. 2001; 23 (4): 145-9.