Fetal Heart Rate Analysis in Pregnancies Complicated by Gestational Diabetes Mellitus: A Prospective Multicentre Observational Study

Objective

Establish whether pregnancies complicated by gestational diabetes mellitus (GDM) are associated with a fetal cardiac phenotype that predisposes to arrhythmia; utilising measurements derived from non-invasive abdominal fetal ECG.

Design

Prospective observational study.

Setting

Three tertiary obstetric units, United Kingdom.

Population

Women aged ≥ 16 years with either GDM or uncomplicated pregnancy (control) who were > 20 weeks gestational age.

Methods

The MonicaAN24 non-invasive abdominal fetal ECG monitor was fitted for overnight recording.

Main Outcome Measure

Calculation of the fetal heart rate (FHR) and fetal heart rate variability (HRV) time domain metrics standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD) and the PR, QRS, QT intervals was performed. Groups were compared using linear regression models (stratified by sleep state) and adjusted for fetal sex and ethnicity.

Results

Ninety-six participants were included. For HRV in sleep state 1F, SDNN was higher for GDM than control participants 12.56 (10.45–16.62)ms versus 8.58 (5.83–9.73)ms [p = 0.01] [median (IQR)]. There were no differences in SDNN in sleep state 2F. No differences were identified in RMSSD in either sleep states or in the cardiac time intervals. We observed a negative correlation between HRV and body mass index/HbA1c and a positive correlation between FHR and body mass index/HbA1c in sleep states 1F/2F.

Conclusions

Alterations of HRV and FHR rate may be associated with a diagnosis of GDM, likely secondary to altered autonomic function in utero.