Table 2.

Outcome parameters comparing uncomplicated and difficult fetal extraction

	outcome parameters mean ± SD / n (%)	group 1: uncomplicated (n = 492)	group 2: difficult (n = 137)	p-value
obstetrical	operation time (in min)	32.2 ± 11.1	42.2 ± 17.7	< 0.001*
	incision-delivery time (in min)	4.6 ± 2.0	6.9 ± 2.9	< 0.001*
	uterotomy-delivery time (in min)	1.3 ± 0.8	2.8 ± 1.5	< 0.001*
	additional instrumental delivery	3 (0.6)	7 (5.1%)	0.003*
maternal	blood loss (in ml)	556 ± 229.9	652.2 ± 322.9	< 0.001*
	delta haemoglobin pre−/postpartum (in g/l)	21.4 ± 11.6	25.8 ± 12.2	< 0.001*
	extensions of the uterine incision	68 (13.8)	34 (24.8)	0.004*
	T-incisions	0	7 (5.1)	< 0.001*
neonatal	umbilical arterial pH < 7.15	10 (2.0)	12 (8.8)	< 0.001*
	Apgar score at five minutes < 7	5 (1.0)	3 (2.2)	0.381
	admissions to the neonatal unit	1 (0.2)	3 (2.2)	0.01
	death	0	1 (0.7)	0.22

SD standard deviation, n (%) number (per cent), BMI body mass index, *significant statistical difference between the groups (p < 0.01)