When my daughter was born, she was diagnosed with a rare genetic blood disorder, neonatal alloimmune thrombocytopenia (NAIT)—the effect of which was the catalyst for me to become a midwife. Although this disease is now well-documented, with many studies being undertaken around the world, while I was a student I was saddened that many of the midwives and paediatricians I spoke to had never heard of NAIT.
The disease, also known as FNAIT (fetal neonatal alloimmune thrombocytopenia), occurs in 1/1000 births (Curtis, 2015). It is the blood platelet equivalent of the red blood cell disease haemolytic disease of the fetus or newborn (HDFN), more commonly known as rhesus disease. Instead of the mother's development of red cell antibodies destroying her baby's red blood cells, NAIT is characterised by the destruction of platelets in the fetus or newborn in response to certain platelet antigens that the fetus has inherited paternally but which are not present in the mother. The mother's body sees these antigens as ‘foreign’ and may respond by producing antibodies against them. Antibodies, an important part of the body's immune system, may cross the placenta, enter the unborn baby's bloodstream and destroy its platelets.
While many cases are mild, NAIT is a significant cause of morbidity and mortality in newborns and is the most common cause of intracranial haemorrhage (ICH) in full-term infants; around 20% of NAIT-affected babies experience spontaneous bleeding in the brain, resulting in severe disability or even death (Peterson et al, 2013). Antenatal screening, administration of prophylactic anti-D immunoglobulin (Ig) and postnatal immunoprophylaxis for HDFN have been undertaken since the early 1970s (Basu et al, 2011), but at present no country screens for NAIT; therefore, it is often misdiagnosed or undiagnosed. There are no warning signs during pregnancy (unless the baby dies in utero), so many pregnant women are totally unaware of the condition.
Red flags at birth are pinpoint bruising (petechiae), which can be mistaken for birth trauma, and hydrocephalus may be evident due to ICH. However, often neither sign is present, but low platelets may be discovered if a full blood count is carried out for another reason, such as a premature birth. After birth, maternal antibodies are no longer crossing through the placenta so the baby should be able to maintain a normal platelet count. However, a platelet transfusion or treatment with intravenous Ig may be necessary if the infant's platelet levels are considered low. An MRI scan should be undertaken to ascertain whether there is any bleeding in the brain.
Once sensitised, subsequent pregnancies may be more severe. Thankfully, however, after diagnosis by genotyping both parents, treatment is available. This consists of weekly infusions of intravenous Ig and may also include steroids. The dosage is dependent on the previous history and whether there has been an ICH. Treatment can be very stressful but can have good outcomes; I had to spend 8 hours a day, once a week during the last 20 weeks of my second pregnancy receiving intravenous Ig treatment. My son's platelet count was also checked at 22 weeks' gestation, via a cordocentesis, to confirm he was responding to treatment. Since he was born, in 2009, more research has been conducted and there is now an algorithm that includes when fetal blood sampling or cordocentesis should be undertaken, and whether a vaginal birth or planned caesarean section is recommended depending on the risk factors present (Pacheco et al, 2011).
During my pregnancies, there was no support group dedicated to NAIT. However, in 2011, the registered charity Naitbabies was formed by Thea Palmer. Thea was affected by NAIT in 2008 when her granddaughter was left severely disabled by two brain haemorrhages, one at around 37 weeks' gestation and one after a failed assisted birth ending in an emergency caesarean section. She was left with complex disabilities including hydrocephalus, epilepsy, cerebral palsy, motor and cognitive delays and registered blind. Thea's colleague, Stacy Corke, has lost three babies due to NAIT.
Naitbabies is the only patient organisation for the disorder. It provides a worldwide parent support network and is extremely supportive both to new parents whose infant has been diagnosed with a condition due to NAIT, or to families who are embarking on subsequent NAIT pregnancies. Its main goal is to see prenatal screening of all pregnant women for NAIT. It contributes to guideline development groups and is consulted by pharmaceutical companies working on treatments. New guidelines for the management of NAIT should be available in October 2016.
If you would like further information on the condition or the organisation, please contact info@naitbabies.org or visit www.naitbabies.org. The charity can also be found on Facebook and Twitter.