A systematic review of cardiac time intervals utilising non-invasive fetal electrocardiogram in normal fetuses

Table 2 Cardiac Time intervals as per the WHO classification

Study	N	Early pre– term (≤ 32 weeks)						Late pre– term (32–37 weeks)						Term (≥ 37 weeks)
(ms)		QT	CI	QRS	CI	PR	CI	QT	CI	QRS	CI	PR	CI	QT	CI	QRS	CI	PR	CI
Abboud et al. (1990) [20]	21							264	224–302	46.3	44–49	103	88–117	245	225–265	46.4	43–50	115.8	91–141
Taylor et al. (2003) [24]	199	251	289–304	47	61–65	102	110–114							259	306–321	55	70–75	105	133–142
Chia et al. (2005) [22]	374	228.4	219–239	49.4	45–54	105.6	99–118	235	230–240	51	48–52	110	107–113	243	239–245	63	51–55	110	108–112
Taylor et al. (2005) [25]	15	255		62		92.5								256		56		103.8
Hayashi R et al. (2009) [23]	48									57						52
Arya et al. (2015) [21]	13			96		132.8				85		128				76		135
Yilmaz et al. (2015)	64	235.5		54	47–57	97.5	91–105	233		56	49–63	109	89–110
Wacker Gussmann et al. (2017) [26]	117							253	247–259	50.3	49–51	107.3	103–110	250	246–254	53	52–54	108	104–112