(983) Longitudinal change in short-term variation with intraamniotic infection after PPROM: a historical cohort study

Friday, January 31, 2025

4:00 PM – 6:00 PM

Submitting Author and Presenting Author(s)

Brynhildur T. Birgisdottir, MD (she/her/hers)

Specialist in Obstetrics and Gynecology
Karolinska University Hospital
Stockholm, Stockholms Lan, Sweden

Coauthor(s)

TA

Tomas Andersson, BSc

Institute of Environmental Medicine, Karolinska Institutet
Stockholm, Stockholms Lan, Sweden
IH

Ingela Hulthén Varli, MD, PhD

Department of Women’s and Children’s Health, Karolinska Institute
Stockholm, Stockholms Lan, Sweden
SS

Sissel Saltvedt, MD, PhD

Department of Women’s and Children’s Health, Karolinska Institute
Stockholm, Stockholms Lan, Sweden
KL

Ke Lu, PhD

Department of Electrical Engineering, Chalmers University of Technology
Gothenburg, Vastra Gotaland, Sweden
FA

Farhad Abtahi, PhD

Department of Clinical Science, Intervention and Technology, Karolinska Institutet
Stockholm, Stockholms Lan, Sweden
U�

Ulrika Åden, MD, PhD

Department of Women’s and Children’s Health, Karolinska Institutet
Stockholm, Stockholms Lan, Sweden
MH

Malin Holzmann, MD, PhD

Department of Women’s and Children’s Health, Karolinska Institutet
Stockholm, Stockholms Lan, Sweden

Objective: Currently used diagnostic tools have been shown to have poor diagnostic performance for intraamniotic infection (IAI). In search of better diagnostic tools we have studied short-term variation (STV) in fetal heart rate in pregnancies with preterm prelabor rupture of membranes (PPROM). We have previously shown that in IAI exposed pregnancies, STV was > 20% lower in the last cardiotocography trace before start of labor, as compared to those not exposed. The current study was aimed at further examining this association by examining the longitudinal change in STV in association with IAI after PPROM.

Study Design: We performed a historical cohort study on 628 singleton pregnancies with PPROM, delivering between 24 + 0 to 33 + 6 gestational weeks. The studied exposure was IAI, using early onset neonatal sepsis as a proxy as no easily available method exists for confirming IAI antepartum, and IAI and early onset neonatal sepsis are strongly associated. The main outcome was STV in fetal heart rate. At least two available cardiotocography traces per fetus were required. A total of 9 690 cardiotocography traces were analyzed.

Results: Fetuses exposed to IAI had a 26.5% steeper decline in their STV during the last 24 hours before the start of labor when compared to fetuses not exposed (95% CI -32.9% to -19.4%; P < 0.001). After adjustment for antenatal corticosteroids, the decline remained significant. The decline became less prominent but remained significant when also adjusting for the baseline frequency (-12.7% [95% CI -19.3% to -5.5%], P < 0.001). In the IAI-exposed group, the baseline frequency increased by 11.1 bpm during the last 12 hours before the start of labor, beyond those who were not exposed (95% CI 8.3 bpm to 13.8 bpm; P < 0.001).

Conclusion: In pregnancies affected by IAI the STV has a steeper decline in the last 24 hours before start of labor as compared to pregnancies not affected by IAI, even after adjustment for increasing baseline frequency. The association of STV in relation to IAI needs to be further studied in order to evaluate and establish STVs usefulness in monitoring patients for IAI.