Article summary Article focus Early antiviral treatment might decrease the mortality of the pregnant women with severe p(H1N1) infection. Being in the third trimester is a risk factor associated with death of the severe p(H1N1)-infected pregnant women. Corticosteroid therapy appeared to have no effect on preventing the severe p(H1N1)-infected pregnant women from death. Key messages The results showed that the pregnant women with severe p(H1N1) infection who took earlier antiviral treatment would more likely reduce the possibility of death. Most of the pregnant women who died of the pandemic H1N1 infection were in their third trimester. Whether to be given corticosteroids therapy showed no significant influence on the prognosis of the pregnant women with severe p(H1N1) infection. Strengths and limitations of this study All the severe cases with p(H1N1) infection were confirmed carefully by a panel consisting of the experts from hospitals, CDCs on the basis of laboratory detection so the confirmation of the cases was credible. However, our estimates may not be generalised to the rest of the severe pregnant cases infected by pandemic H1N1 as the relatively small sample and lack of the cases' underlying medical conditions limited the ability of extrapolation.