It might be a tall order, but breastfeeding more than five children, as well as breastfeeding for a cumulative eight years, can dramatically lower a mother’s chance of developing hypertension, a pair of researchers found in a study of more than 3,000 postmenopausal women.

The practice—which includes more than 80 percent of mothers post-delivery—has long been known for its health benefits: fewer pediatric allergies, less celiac disease and lowered risks of obesity and diabetes in breastfed children. Women are recommended to breastfeed exclusively for at least six months postpartum, with ongoing partial breastfeeding after other foods are introduced to the child’s diet.

“However, the effects of breastfeeding on maternal health have been little studied compared with the effects on the children,” researchers Sangshin Park and Nam-Kyong Choi wrote in the American Journal of Hypertension.

Past research has linked breastfeeding to reduced risks of diabetes, dyslipidemia, metabolic syndrome, coronary heart disease and cardiovascular illnesses in mothers, the authors said, but hypertension is often left out of the picture in these studies.

Park and Choi’s study population, drawn from the Korea National Health and Nutrition Examination Survey, numbered 3,119 nonsmoking postmenopausal women who were 50 years old or up. Accounting for factors like insulin sensitivity and obesity, the researchers analyzed how breastfeeding related to hypertension risk in the cohort.

They found the odds of hypertension were lowest in women who breastfed many children—5 to 11—and spent the longest time breastfeeding—between 96 and 324 months. Women in the highest quintile of number of breastfed children saw a 51 percent reduced risk of hypertension, while those in the highest quintile of time spent breastfeeding experienced a 45 percent lowered risk.

Adversely, 10.2 percent of hypertension in the study population could be attributed to women who breastfeed three or fewer children, Park and Choi wrote. Six-point-five percent of total hypertension was attributed to breastfeeding for 56 months—about four and a half years—or less.

Their results backed up suggestions that breastfeeding can have vast benefits for mothers as well as children, the co-authors wrote, but scientists are still unsure of how breastfeeding leads to a lowered risk of hypertension—or any chronic illness.

Park and Choi wrote that a popular theory revolves around “maternal metabolism,” or the idea that breastfeeding after pregnancy resets a woman’s metabolism, consequently reducing her risk of disease. The increased uptake of oxytocin, as well as reduced levels of ghrelin and protein peptide YY during breastfeeding, could also contribute, they said.

“Our findings endorsed the current recommendations of breastfeeding for the benefit of maternal health in mothers’ later lives,” the authors wrote. “Greater attention should be paid to breastfeeding in developing more effective hypertension prevention strategies in parous postmenopausal women.”