Fetal Tachycardia in the Setting of Maternal Intrapartum Fever and Perinatal Morbidity

Abstract

Objective The fetal consequences of intrapartum fetal tachycardia with maternal fever or clinical chorioamnionitis are not well studied. We evaluated the association between perinatal morbidity and fetal tachycardia in the setting of intrapartum fever.

Study Design Secondary analysis of a multicenter randomized control trial that enrolled 5,341 healthy laboring nulliparous women ≥36 weeks' gestation. Women with intrapartum fever ≥ 38.0°C (including those meeting criteria for clinical chorioamnionitis) after randomization were included in this analysis. Isolated fetal tachycardia was defined as fetal heart rate (FHR) ≥160 beats per minute for at least 10 minutes in the absence of other FHR abnormalities. FHR abnormalities other than tachycardia were excluded from the analysis. The primary outcome was a perinatal composite (5-minute Apgar's score ≤3, intubation, chest compressions, or mortality). Secondary outcomes included low arterial cord pH (pH < 7.20), base deficit ≥12, and cesarean delivery.

Results A total of 986 (18.5%) of women in the trial developed intrapartum fever, and 728 (13.7%) met criteria to be analyzed; of these, 728 women 336 (46.2%) had maternal-fetal medicine (MFM) reviewer-defined fetal tachycardia, and 349 of the 550 (63.5%) women during the final hour of labor had validated software (PeriCALM) defined fetal tachycardia. After adjusting for confounders, isolated fetal tachycardia was not associated with a significant difference in the composite perinatal outcome (adjusted odds ratio [aOR] = 3.15 [0.82–12.03]) compared with absence of tachycardia. Fetal tachycardia was associated with higher odds of arterial cord pH <7.2, aOR = 1.48 (1.01–2.17) and of infants with a base deficit ≥ 12, aOR = 2.42 (1.02–5.77), but no significant difference in the odds of cesarean delivery, aOR = 1.33 (0.97–1.82).

Conclusion Fetal tachycardia in the setting of intrapartum fever or chorioamnionitis is associated with significantly increased fetal acidemia defined as a pH <7.2 and base excess ≥12 but not with a composite perinatal morbidity.

Key Points

• The perinatal outcomes associated with fetal tachycardia in the setting of maternal fever are undefined.

• Fetal tachycardia was not significantly associated with perinatal morbidity although the sample size was limited.

• Fetal tachycardia was associated with an arterial cord pH <7.2 and base deficit of 12 or greater.

Keywords

intrapartum fever - fever - intrapartum - fetal tachycardia - neonatal morbidity - fetal heart rate monitoring - umbilical artery pH - acidemia - fetal acidemia - base deficit

• References

• 1 Alexander JM, McIntire DM, Leveno KJ. Chorioamnionitis and the prognosis for term infants. Obstet Gynecol 1999; 94 (02) 274-278
• 2 Higgins RD, Saade G, Polin RA. et al; Chorioamnionitis Workshop Participants. Evaluation and management of women and newborns with a maternal diagnosis of chorioamnionitis: summary of a workshop. Obstet Gynecol 2016; 127 (03) 426-436
• 3 Soper DE, Mayhall CG, Dalton HP. Risk factors for intraamniotic infection: a prospective epidemiologic study. Am J Obstet Gynecol 1989; 161 (03) 562-566 , discussion 566–568
• 4 Gibbs RS, Duff P. Progress in pathogenesis and management of clinical intraamniotic infection. Am J Obstet Gynecol 1991; 164 (5, pt. 1): 1317-1326
• 5 Macones GA, Hankins GD, Spong CY, Hauth J, Moore T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. Obstet Gynecol 2008; 112 (03) 661-666
• 6 Rouse DJ, Landon M, Leveno KJ. et al; National Institute of Child Health And Human Development, Maternal-Fetal Medicine Units Network. The Maternal-Fetal Medicine Units cesarean registry: chorioamnionitis at term and its duration-relationship to outcomes. Am J Obstet Gynecol 2004; 191 (01) 211-216
• 7 Honjo S, Yamaguchi M. Umbilical artery blood acid-base analysis and fetal heart rate baseline in the second stage of labor. J Obstet Gynaecol Res 2001; 27 (05) 249-254
• 8 Strachan BK, Sahota DS, van Wijngaarden WJ, James DK, Chang AM. Computerised analysis of the fetal heart rate and relation to acidaemia at delivery. BJOG 2001; 108 (08) 848-852
• 9 Asakura H. Fetal and neonatal thermoregulation. J Nippon Med Sch 2004; 71 (06) 360-370
• 10 Bloom SL, Spong CY, Thom E. et al; National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Fetal pulse oximetry and cesarean delivery. N Engl J Med 2006; 355 (21) 2195-2202
• 11 Neonatal Encephalopathy and Neurologic Outcome. Second EditionReport of the American College of Obstetricians and Gynecologists' Task Force on neonatal encephalopathy. Pediatrics 2014; 133 (05) e1482-e1488
• 12 Edwards RK, Cantu J, Cliver S, Biggio Jr. JR, Owen J, Tita ATN. The association of maternal obesity with fetal pH and base deficit at cesarean delivery. Obstet Gynecol 2013; 122 (2, pt. 1): 262-267
• 13 Weiner S. 753: Independent validation of a fetal heart rate pattern recognition software. Am J Obstet Gynecol 2013; 208 (01) S316-S317
• 14 Malin GL, Morris RK, Khan KS. Strength of association between umbilical cord pH and perinatal and long term outcomes: systematic review and meta-analysis. BMJ 2010; 340: c1471
• 15 Sherer DM, Onyeije CI, Binder D, Bernstein PS, Divon MY. Uncomplicated baseline fetal tachycardia or bradycardia in postterm pregnancies and perinatal outcome. Am J Perinatol 1998; 15 (05) 335-338
• 16 Beard RW, Filshie GM, Knight CA, Roberts GM. The significance of the changes in the continuous fetal heart rate in the first stage of labour. J Obstet Gynaecol Br Commonw 1971; 78 (10) 865-881
• 17 Gilstrap III LC, Hauth JC, Hankins GD, Beck AW. Second-stage fetal heart rate abnormalities and type of neonatal acidemia. Obstet Gynecol 1987; 70 (02) 191-195
• 18 Liu L, Tuuli MG, Roehl KA, Odibo AO, Macones GA, Cahill AG. Electronic fetal monitoring patterns associated with respiratory morbidity in term neonates. Am J Obstet Gynecol 2015; 213 (05) 681.e1-681.e6