GSTM1 and pulmonary arterial hypertension: Finally, Table 3, which shows the multivariate logistic regression analysis carried out with the total number of patients in the study and the evaluation of the differences between the study groups (i-PPH and non-i-PPH), shows that parity was significantly associated with the absence of described PPH; in contrast, antepartum Hb and C-section were significantly associated with the identification of PPH.