(445) Physical activity in pregnant persons with a prior preterm birth: impact of cervical insufficiency (CI)

We sought to determine the association between objectively quantified physical activity and GA at delivery among patients with a prior SPTB who did and did not develop CI in the current pregnancy.


Study Design: Primary analysis of a prospective observational cohort designed to identify factors associated with recurrent SPTB. Patients with singleton, non-anomalous gestations and ≥1 prior SPTB < 35 wks were recruited, 9-14 wks, 2017-2022. Participants were provided FitBit activity trackers for the remainder of pregnancy and instructed to maintain their usual activity. Those with ≥7 valid monitoring days (FitBit recorded heart rate for ≥80% of the day) were included. Patients with a mid-trimester CL < 25mm & US- or exam-indicated cerclage in the current pregnancy were considered to have CI. Daily steps and intensity were compared by those with and without CI.  The primary outcome was GA at delivery. Fixed-effects linear regression was used to examine whether activity parameters were associated with GA at delivery and to account for varying numbers of obs/subject.

Results:

99 patients met inclusion criteria; 31 (31%) had CI. Those with CI delivered at 35.4 ± 4.1 wks vs. 36.8 ± 3.1 wks (no CI), p=0.058. The cohort was racially (40% Black) and ethnically (16% Hispanic) diverse. There were 6847 Fitbit wear days (median 60 days/person). For those with CI, daily steps, light activity min/day, and fairly/very active min/day were higher in early pregnancy and decreased mid-pregnancy; these activity patterns differed significantly from those without CI (Figure). In separate regression models including all patients and controlling for the diagnosis of CI and a priori for other known PTB risk factors, median steps/day (β=0.10, 95% CI 0.09, 0.12), light activity min/day (β=0.002, 95% CI 0.001, 0.002), and fairly/very active min/day (β=0.006, 95% CI 0.003, 0.009) were associated with GA at delivery (all p< 0.001).


Conclusion: Patients with a prior SPTB < 35 wks and CI have different physical activity patterns compared to those without CI. Physical activity amount and intensity are associated with GA at delivery.