Our gestational results, in general, were favorable since we had no maternal, fetal or neonatal deaths. However, 72.7% (16/22) of our pregnancies had adverse obstetrical outcomes. In a recent review about pregnancies in patients with TAK, the number of live births (84%) and of general adverse outcomes (51%) were lower than those reported in this study [16]. Other publications have demonstrated fewer adverse pregnancy outcomes, ranging from 40 to 47% [17, 18].

The main complications described in this study were worsening blood pressure, preeclampsia, premature birth, emergency cesarean section, small-for-gestational-age newborns and admission to neonatal intensive care unit. Such complications seem to be related to the diagnosis of TAK associated with previous arterial hypertension and renal involvement, according to previous reports [1, 2, 19,20,21]. The large number of patients with these events in this study may justify the higher number of adverse obstetric outcomes compared to previous studies [19, 20].

About a third of pregnancies developed preeclampsia, which is compatible with previous studies that observed a prevalence between 11 to 73% and considerably higher than general population (4 to 7%) [1, 16,17,18, 20,21,22,23]. One meta-analysis demonstrated that low dose aspirin reduced the incidence of preeclampsia in patients at high risk for developing the disease, especially in its severe form, and also reduced the incidence of intrauterine growth restriction [24]. Although there are no specific studies considering patients with vasculitis and the incidence of preeclampsia is still high despite the use of aspirin, it seems reasonable to use this medication in pregnant women with these morbidities.

Studies have observed a direct relationship between maternal complications and uncontrolled blood pressure, with worse maternal–fetal outcomes in hypertensive patients. Complications such as preeclampsia, fetal growth restriction, miscarriage, prematurity, heart failure, aortic dissection, stroke, progression of renal failure, maternal and fetal death have been described [4, 9].

A recent report described a very low incidence of preeclampsia/eclampsia (5.3%) in 38 pregnancies, but the majority of the 20 patients were diagnosed with TA after gestational period [19]. Hidaka et al. analyzed 18 pregnancies in 10 patients with TAK, among which only two required antihypertensive medication during pregnancy. Fetal growth restriction occurred in only 11.1% and just two patients had uncontrolled hypertension, without other maternal or fetal significant complications [20]. In the same way, Abisnor et al. analyzed 43 pregnancies in 33 patients, 15 (35%) had previous systemic arterial hypertension, 5 (9%) had preeclampsia and 6 (14%) had fetal growth restriction [18]. Considering the six included pregnancies in which patients were normotensive, two developed preeclampsia and one presented late fetal growth restriction. The other three had no complications. These results suggest that absence of chronic hypertension is associated with a better prognosis during pregnancy.

The occurrence of secondary hypertension seems to be related to aortic narrowing, renovascular origin, reduced vascular wall elasticity and aortic regurgitation [9]. Patients with renovascular involvement and subsequent arterial hypertension are at higher risk of developing maternal–fetal complications [25]. Some studies have associated the involvement of the abdominal aorta and renal arteries with a higher incidence of hypertension, preeclampsia and fetal growth restriction [21, 25]. Among twelve pregnancies of patients with renal involvement in this study, only two remained normotensives during follow-up. All others evolved with uncontrolled blood pressure, including five cases with diagnosis of preeclampsia, and three were premature deliveries.

Premature delivery occurred in 18.1% of patients, a frequency that is higher than that found in the general population. In Brazil, the incidence of preterm birth is estimated at 11% [26]. Pedreira et al. also reported a lower incidence of preterm delivery, occurring only in 7.9% of pregnancies [19].

Intrauterine growth restriction was observed in almost a quarter of patients in this study, being compatible with the frequency reported in the literature considering pregnant women diagnosed with TAK (11 to 29%) [20]. The incidence of IUGR in general population is difficult to interpret as some studies use the term small for gestational age, which may include both newborns with growth restriction as well as small constitutional ones. It is estimated that the incidence of small for gestational age newborns in low-risk pregnancies is approximately 7 to 15% [24]. In our center, we perform monthly obstetric ultrasound after 24 weeks for early diagnosis and appropriate follow-up of growth restricted fetuses.

When comparing the Ishikawa criteria with obstetric and perinatal complications, there is an association between the presence of clinical complications and adverse outcomes in this study, similar to data previously published in the literature [27]. The Ishikawa classification represents the natural history of the disease and its clinical manifestations that directly influence the prognosis. According to Ishikawa, approximately one third of patients classified as IIb and III at the time of diagnosis died within five years, despite treatment [9]. Of the five patients classified as Ishikawa IIb and III in this study, all had uncontrolled blood pressure, and two were diagnosed with severe preeclampsia. Two patients had spontaneous premature deliveries and two of the newborns required admission to NICU, including the newborn who had very low birth weight.

Pregnancy apparently did not induce disease activity. Previous studies concluded that pregnancy could attenuate the inflammatory response to TAK during and even after pregnancy [20, 28]. However, physiological changes in pregnancy such as increased circulatory volume and cardiac output are associated with possible clinical repercussions, such as exacerbation of aortic regurgitation, arterial hypertension, and congestive heart failure [20].

The cesarean rate observed in the present study was 68.1%, which is compatible with the rate found in the literature (mean of 39.6 to 68%) [5, 21,22,23]. Ishikawa and Matsuura recommend C-section in groups IIb and III, mainly in patients with severe hypertension and/or retinopathy, while in groups I and IIa there is a significant increase in blood pressure in the first stage of childbirth despite the use of medications [21].

The mean APGAR score of all newborns was 8.65/9.2, similar to the findings found by Mandal et al. [21]. A study by Hauenstein et al. observed that 83.9% of newborns were born healthy and only 2.8% were stillborn [29].

The main limitations of the current study are the retrospective design, which can lead to information biases, and relatively small sample size, although TA is a rare disease with few of reports during pregnancy. Furthermore, the incidence of miscarriage is underestimated because patients could have miscarried before starting prenatal care or reaching the tertiary hospital where the study was conducted.