Objective: This study was undertaken to determine whether women with recurrent spontaneous preterm births (rSPBs) have different clinical characteristics or systemic markers than those with isolated preterm (iSPBs) or recurrent term births (rTBs), when assessed remote from delivery.
Study design: We compared clinical characteristics and findings (including cervical ultrasound, bacterial vaginosis, fetal fibronectin), maternal plasma markers obtained at 22 to 24 weeks' gestation (inflammatory cytokines, cortisol, and corticotrophin-releasing hormone), between women with rSPBs (2 or 3 consecutive SPBs and no TBs), iSPBs (1 SPB and 1 or 2 TBs), and rTBs (2 or 3 consecutive TBs and no SPBs).
Results: A total of 1257 women met our inclusion criteria; 47 rSPBs, 241 iSPBs (80 current and 161 prior iSPBs), and 969 rTBs. Before pregnancy, women with rSPBs had lower weights (P < .0001) and body mass indexes (BMIs) (P < .001), and were more likely to be less than 100 lbs (P = .008) or less than 19.8 kg/m2 BMI (P = .001). At 22 to 24 weeks those with rSPBs remained lighter and leaner, and had more advanced Bishop scores than iSPBs and rTBs. Ultrasound demonstrated progressive decrease in cervical length for those with rTBs, prior iSPBs, current iSPBs, and rSPBs, and also progressively more frequent short cervixes with worsening history (P < .001). Cervical length was shorter for women of lower pregravid weight and BMI, but not with shorter height. At 22 to 24 weeks, women with rSPBs had more common uterine contractions and tocolytic agents, but not more infections or antibiotic therapy. Those with an SPB in the current gestation had higher fetal fibronectin levels and more frequent vaginal bleeding, regardless of prior outcome. Maternal cortisol and corticotrophin-releasing hormone were higher in women with iSPBs and rSPBs than in rTB controls, (P = .001 and .0027), a finding more apparent with SPB in the current pregnancy. However, maternal cytokines were not increased with either iSPBs or rSPBs.
Conclusion: Women with rSPBs are leaner, contract more, have shorter cervixes, and have more advanced Bishop scores than women with iSPBs or rTBs.