Dependency of magnetocardiographically determined fetal cardiac time intervals on gestational age, gender and postnatal biometrics in healthy pregnancies

Table 1 CTI dependency on gestational age. Dependency of fetal cardiac time intervals on gestational age (in weeks): coefficients of determination (r ²), y-intercepts, slopes and the p-value of the slopes (values < .05 in bold type). Linear regression parameters are given for each disjunct interval (upper rows) and each composite interval (lower rows). Non-linear regression parameters are also given for those intervals in which an improved model fit was found (quadratic: PQ and PR interval, double logarithmic: QRS complex).

	regression type	N	r ²	y-intercept (ms)	slope (ms/week)	p	slope (ms/week²)	p
P wave	linear	228	0.67	14.0	1.37	<0.001
PQ interval	linear	228	0.07	67.7	-0.49	<0.001
PQ interval	non-linear	228	0.13	14.2	3.38	0.021	-0.07	0.008
QRS complex	linear	230	0.62	19.3	0.92	<0.001
ln (QRS)	non-linear	230	0.66	1.8	0.60*	<0.001
ST segment	linear	217	0.01	60.4	0.32	0.169
T wave	linear	216	0.00	126.0	0.00	1.000
PR interval	linear	228	0.16	81.7	0.88	<0.001
PR interval	non-linear	228	0.21	20.0	5.35	<0.001	-0.08	0.002
QT interval	linear	216	0.07	205.8	1.24	<0.001
QTc interval	linear	216	0.06	326.6	1.65	<0.001

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