By Ruth Murphy | Jun 22 2017The Irish Blood Transfusion Service (IBTS) have added new restrictions on blood donation which may prevent a significant portion of people who were previously eligible to donate from giving blood. The new restrictions apply to women aged under 26, who are below 5’ 6” (168cm), and weigh less than 10st 3lb (65kg).Not all women who fit this description will be barred from donating blood and the IBTS released a chart, that can be downloaded from their website giveblood.ie, which shows the cut off for giving blood. It is a simple sliding chart and those closer to 5’6’ are more likely to be able to give blood but those as small as 5’ would have to weigh a lot more in order to be permitted to give blood. Anyone who is 4’ 10” or smaller cannot give blood.The reasons given for these changes, as explained in the document containing this chart, are that “Donation research and medical evidence have shown that based on height and weight, female donors of smaller build…are at an increased risk of fainting following blood donation.”Despite the stated connection to fainting, those who fit this description but have previously donated blood without fainting are not permitted to give blood until they reach 26 years of age or gain weight or grow taller.In conversation with the University Observer, Dr. Nina Orfali of the IBTS explained that "an individual’s height and weight determine their blood volume. Removing more than 15% of a person’s blood volume has been linked to increased rates of vasovagal reactions, ranging from light-headedness to loss of consciousness."The University Observer also received the results of an American study, from the IBTS, which featured in the journal "Transfusion." The study, published by the National Institute of Health, found that "Young age, low EBV (Estimated Blood Volume), and first-time donation status are the major correlates of prefaint reactions" and suggested that "deferral of donors with low EBV who are less than 23 years old may offer a rational approach to protecting donors at greater risk of reactions without jeopardizing the adequacy of the blood supply." Another study in the same journal states that "An increased risk of vasovagal reactions (VVR) has been associated with a number of factors including young age,... weight,... low estimated blood volume... and female sex."The IBTS has previously been criticised for its strict restrictions on blood donation, particularly when it comes to men who have sex with men (MSM). Previously MSM were unable to give blood as they were seen as being at a high risk of getting HIV and there is a window in which HIV tests are not entirely effective. This ban was lifted recently and replaced with a year long deferral meaning that MSM can give blood if they abstain from sex with men for one year.