(1033) Variation in Fetal Heart Rate Tracing and Adverse Outcomes among Pregnancies Complicated by Hypertensive Disorder

To compare the fetal heart rate tracing (FHRT) and adverse outcomes among hypertensive and non-hypertensive women who delivered at term (> 37 wks).

Study Design:

The inclusion criteria of the retrospective study were consecutive individuals with non-anomalous singletons who delivered at > 37 wks over 15 months. The groups were stratified by the presence or absence of hypertensive disorder of pregnancy (HDP), defined as gestational and chronic hypertension.   Using the ACOG guidelines, clinicians—blinded to maternal characteristics, BP status, and outcomes—interpreted the FHRT for the last 60 mins of labor. Composite neonatal and maternal adverse outcomes (CNAO, CMAO) were compared between the groups. Chi-square test was used to compare groups. Odds Ratios (OR) and adjusted OR were calculated using a multivariate binomial logistic regression model with permuted omnibus tests to identify confounding factors.

Results: Of the 5,160 deliveries during the study period, 3,166 (61%) met the inclusion criteria and among them 1,062 (33%) had HDP. Pregnancies complicated by HDP were significantly more likely to have minimal variability (p< 0.01). Decelerations occurred at similar rate. The rate of category I, II and III tracings were similar (Table 1). Cesarean delivery was  comparable among the two groups after adjustment. CNAO of newborns of individuals with HDP (2.5%) was significantly higher than newborn of normotensive individuals (1.0%; aOR 2.32 95%CI 1.21 – 4.49). CMAO was significantly higher in the HDP (9.9%) than normotensive group (6.8%; aOR 1.56 95% CI 1.17 – 2.07); Table 2).  Apgar score < 7 at 5 min and neonatal seizure were the only components of the CNAO that differed significantly.

Conclusion: Minimal variability was the only fetal heart rate characteristic which differed significantly among hypertensive vs. normotensive individuals.  Neonatal and maternal adverse outcomes were significantly higher in the hypertensive group. Intervention trials mitigating the increased likelihood of adverse outcomes among term individuals with hypertensive disorder are warranted.