Fetal heart rate variability in growth-restricted fetuses. Substudy of NTR 7132 'Fetal myocardial deformation throughout pregnancy'.

Women, pregnant from a growth restricted fetus, will be asked for a fetal electrocardiography measurement on a weekly base from the moment of diagnosis until birth. Pregnant women, pregnant from a singleton, will be asked for one-time fetal electrocardiography. Inclusions from the control group will be matched for gestational age with the FGR group.

FECG measurements will take 40 minutes. Women are lying in a semi recumbent position. The abdominal skin is prepared with abrasive paper before application of the electrode patch. During the measurement, a short fetal positioning ultrasound is performed every 15 minutes. Data is analyzed offline. We want to study the differences in fetal heart rate variability between healthy and growth restricted fetuses.

FGR induced cardiac remodeling also affects fetal heart rate variability (fHRV). Chronic hypoxia in growth-restricted fetuses due to placental dysfunction can interfere with maturation of the autonomic nerve system, leading to a decrease in fHRV. This can be measured wit fetal electrocardiography.

Pregnant women, pregnant from a singleton, will be asked for a one-time only fetal electrocardiographic measurement. Inclusions for the control group are matched for gestational age with FGR inclusions. Women, pregnant from a growth restricted fetus, will be measured on a weekly base from the moment of diagnosis until birth.

The non-invasive fetal electrocardiogram is a non-invasive, transabdominal recording method. It uses multiple electrodes on the maternal abdomen to determine the fetal and maternal heart rhythm and some parts of the heart’s electrical conduction system and it registers the contractions. Women will be lying down in a semi recumbent position during the measurement. The electrode patch will be applied by trained staff, to make sure application and connection will be done in the correct way and avoid unnecessary technical problems. Before applying the electrode patch on the abdomen, the abdominal skin will be cleaned with water and soap. Next, the abdominal skin will be prepared with abrading paper to remove dead skin cells, as this is essential for proper guidance of the electrical currents and to optimize the impedance. This is a one-time action as the adhesive properties of the patch ensure that it will remain on the same location throughout the delivery. The measurement will last 40 minutes. During the measurement, short ultrasound measurements will be made (at the start of the measurements and approximately every 15 minutes) to determine the position of the fetus. Information concerning the fetal position is necessary for the analysis of the fECG waveforms. Data will be stored and analyzed offline.