Inflammatory and Infectious Risk Factors Are Associated with the Response to Tocolysis in Patients with Preterm Labor

Objective: Inflammation/infection is the most frequent conditions leading to preterm delivery (PTD). A few studies have assessed the clinical efficacy of long-term tocolysis with ritodrine hydrochloride. In this study, the relationship among inflammatory/infective risk factors of PTD, the response to long-term tocolysis, and timing of delivery were evaluated in women with preterm labor.

Methods: On the basis of different responses to long-term tocolysis, defined as ≥ 7 days tocolysis, the cohort were classified as: (i) patients delivering at term (Group A) and (ii) patients delivering preterm (group B). Group B was subclassified as: (i) delivery before 48 h (group B1); (ii) delivery between 48 h and 7 days (Group B2), and (iii) delivery after 7 days (Group B3). Group B is divided in early preterm (<32 weeks) (Group B early) and late PTD (32-36 weeks) (Group B late).

Results: Group A delivered at term and Group B preterm. Group B showed significantly higher (p < 0.0001) rate of CRP, bacterial vaginosis, and chorioamnionitis at placental histological examination than Group A. The same parameters were statistically higher (p < 0.0001) in group B1 than in B3. CRP, chorioamnionitis at placental histological examination was statistically higher (p < 0.0001) in Group B early than in Group B late.

Conclusions: This retrospective study suggested that in women affected by preterm labor, the long-term tocolysis with intravenous ritodrine is able to prolong gestation beyond 7 days, in absence of inflammatory/infective risk factors of PTD.