The Relationship between Nifedipine and Postpartum Blood Loss in Patients with Preterm Labor

Background: The purpose of the study, to determine whether exposure to nifedipine before delivery is associated with an increased risk of postpartum blood loss in patients with preterm labor. Methods: This was a retrospective study screening a total of 486 patients who were admitted due to preterm labor from 2012 to 2019. Patients who were given nifedipine for tocolysis before delivery were considered as the study group (n: 240), and the patients who gave birth without getting tocolysis were considered as the control group (n: 246). The dose of nifedipine used during the last 24 hours, 72 hours and 1 week before delivery, the total dose of nifedipine given and the duration from the last dose to the delivery were recorded separately. Hemoglobin and hematocrit and platelet values measured before and 6 hours after delivery were recorded and postpartum bleeding amount was calculated. Results: No significant difference is observed in terms of mean difference between pre/postpartum hemoglobin and hematocrit levels between control group and nifedipine group (p > 0.05). But when subgroups that are created according to the time of use of nifedipine before delivery, a positive correlation was observed between difference in hemoglobin and hematocrit levels between prepartum and postpartum and nifedipine dosage for the last 24 hours (r = 0.176, p = 0.006), (r = 0.139, p = 0.030), but not for 72 hours or one week. Conclusions: The use of nifedipine in patients with preterm labor for tocolysis may be associated with increase in postpartum blood loss in the last 24 hours before delivery.