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Thrombotic microangiopathy

Pregnancy outcomes in aHUS

“pregnancies in women with aHUS are frequently successful”

As life-threatening episodes of thrombotic microangiopathy (TMA) can be triggered by pregnancy, many women with atypical haemolytic uraemic syndrome (aHUS) decide not to have children. However, a new study reports that pregnancy outcomes in patients with aHUS are much better than is commonly appreciated.

The researchers found that only seven of 27 (26%) pregnancies in 14 women with aHUS were complicated by episodes of TMA. These episodes occurred post-partum in four women (three of whom had additional triggers for TMA) and following an initial diagnosis of pre-eclampsia or HELLP syndrome in three women. Episodes of TMA were more common in 18 retrospectively analysed pregnancies that were managed without preventative therapy (33%) than in nine pregnancies that were prospectively followed in a specialized unit, most of which were managed with infusions of fresh frozen plasma (11%). Although 71% of the women had mutations in genes that encode complement proteins or regulators, no associations were found between these mutations and pregnancy outcomes.

Overall, 21 pregnancies (78%) resulted in a live birth, of which 19 were full term. Four pregnancies resulted in early spontaneous abortions and two preterm infants were stillborn. Among the pregnancies that were complicated by TMA, four resulted in live births (two of which were full term), one resulted in a preterm stillbirth and two resulted in early, spontaneous abortions.

The long-term renal outcomes of the women with aHUS were poor, but whether renal prognosis was influenced by pregnancy could not be determined. At study end, only two women had normal kidney function, four had chronic kidney disease stage 1–4 and eight had progressed to end-stage renal disease.

The researchers conclude that pregnancies in women with aHUS are frequently successful and fetal outcomes are excellent in those who do not experience antenatal episodes of TMA. They comment that close monitoring of pregnancies in women with aHUS is essential and recommend follow-up in specialized units.


  1. 1

    Gaggl, M. et al. Maternal and fetal outcomes of pregnancies in women with atypical hemolytic uremic syndrome. J. Am. Soc. Nephrol. (2017)

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Carney, E. Pregnancy outcomes in aHUS. Nat Rev Nephrol 14, 143 (2018).

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