Turner Syndrome
One of the most common chromosomal abnormalities in women, TS occurs in 1 in 2500 live female births and is characterised complete or partial absence of the X chromosome32. Of these, up to 50% are expected to have cardiovascular malformations in addition to the common features of short stature and primary ovarian insufficiency33. Only 5 – 6% will have a spontaneous pregnancy34. For women with TS, oocyte donations have presented the opportunity for the majority to carry a pregnancy, but there is some debate whether the risk is too high34,35. Although TS itself is an increased relative risk of AD, estimated maternal mortality rates of 2% in TS from AD or rupture34. A study by Bernard et al. regarding outcomes in 480 patients found 5.6% had spontaneous pregnancies; none of these were associated with aortic root dilatation or aortic dissection36. Evidence shows that different karyotypes in TS may offer different risks; in Bernard’s study, mosaic karyotype predisposed to spontaneous pregnancy, milder phenotype and therefore may have a lower risk to other karyotypes34,36. The recommendations from the 2016 Cincinnati International TS meeting suggested that full imaging, exercise testing and TTE should be performed 2 years prior to planned pregnancy or assisted reproductive therapy37. Any female with a prior history of AD should be advised against pregnancy, or if already pregnant, to be monitored closely and deliver by Caesarean. If there is no evidence of dilatation, TTE should be carried out at least once; suggested around 20 weeks, but if there is any evidence of dilatation, hypertension, BAV or other risk factors, monitored at least 1 to 2 monthly up to 6 months postpartum37. Using aortic size index (ASI)— absolute aortic diameter in cm divided by body surface area, which better predicts AD risk for TS— vaginal delivery is feasible at ASI less than 2cm. Above 2cm and less than 2.5cm, Caesarean should be considered, but above 2.5cm Caesarean is recommended37.