It is known to have health benefits for both mother and baby, but a new study shows that breastfeeding can also lower the chance of mothers developing high blood pressure - even decades later.The researchers, from the University of Western Sydney, also found that the longer a woman breastfed, the lower her odds of developing high blood pressure before the age of 64.They investigated the relationship between breastfeeding history and the prevalence of high blood pressure in 74,785 Australian women who were aged 45 years and over.Data for the research was drawn from the 45 and Up Study - a large scale study of healthy ageing involving over 260,000 men and women in New South Wales, and the largest study of its kind in the southern hemisphere.Principal researcher on the study, Dr Joanne Lind from the UWS School of Medicine, said the findings reinforce the importance of breastfeeding for both child and mother.Women aged 45 to 64 years, who had breastfed for more than six months in their lifetime, or more than three months per child, had a lower likelihood of having high blood pressure.'Hopefully this research will add to the discussion between women and their physicians and midwives,' said Dr Lind, a senior lecturer in molecular biology and genetics.'Whenever possible, women should be encouraged to breastfeed as long as possible as the protective effect of breastfeeding increases with the length of time breastfeeding.'While the reasons for the reduced likelihood of having high blood pressure are still unknown, it is possible that hormones released while breastfeeding provide long term benefits to the mother's cardiovascular system.'Despite us not fully understanding the protective mechanism, breastfeeding history should now be considered when assessing a patient's likelihood of having high blood pressure in later life,' said Dr Lind.'Even when we took into account potentially contributing factors such as family history and lifestyle - physical activity and BMI, history of smoking, drinking alcohol - we still found an association between breastfeeding and a lower likelihood of having high blood pressure.'The current World Health Organisation (WHO) recommendations encourage breastfeeding for a minimum of six months per child.Dr Lind added: 'This study provides further support for the WHO recommendations, as both the total amount of time a woman spends breastfeeding in her lifetime, and the length of time she spends breastfeeding each child, are associated with a significant reduction in the likelihood of having high blood pressure.'