Table 1 In- and exclusion criteria

Pregnant with a singleton pregnancy.

Pre-existing maternal disease that might influence fetal development (e.g. diabetes mellitus, pre-existent hypertensive disease or chronic medication use for maternal illness).

Uncomplicated pregnancy at the time of inclusion.

Abnormalities found at any ultrasound scan that might influence fetal cardiac function (e.g. fetal cardiac arrhythmias or congenital cardiac abnormalities).

GA <16+0 weeks

Contra-indications to abdominal patch placement of the NFMS (e.g. dermatologic diseases of the abdomen precluding preparation of the abdomen with abrasive paper, or external or implanted electrical stimulator).

Oral and written consent is obtained.

Insufficient ability in understanding Dutch or English language.

Maternal age ≥ 18 years.