Table 3 Parameters of twins for the whole group and according to type of conception (spontaneous, ART).

Parameters		Whole group		ART
				No		Yes
		Number	%	Number	%	Number	%
IUGR: intrauterine growth restriction; ART: assisted reproductive technology
I twin presentation	head	268	62.2	122	28.31	146	33.87
	pelvis	142	32.9	66	15.31	76	17.63
	other	21	4.9	10	2.32	11	2.55
II twin presentation	head	222	51.5	97	22.51	125	29.00
	pelvis	107	24.8	52	12.06	55	12.76
	other	102	23.7	49	11.37	53	12.30
I twin gender	male	226	52.4	105	24.36	121	28.07
	female	205	47.6	93	21.58	112	25.99
II twin gender	male	203	47.1	95	22.04	108	25.06
	female	228	52.9	103	23.90	125	29.00
Twins comorbidities	none	360	83.5	163	37.82	197	45.71
	malformations	16	3.7	9	2.09	7	1.62
	IUGR	3	0.7	2	0.46	1	0.23
	asphyxiation	13	3.0	6	1.39	7	1.62
	multiple	11	2.6	4	0.93	7	1.62
	other	28	6.5	14	3.25	14	3.25
Maturation	no	345	80.0	157	36.43	188	43.62
	yes	86	20.0	41	9.51	45	10.44
Chorionicity	dichorionic	404	93.7	190	44.08	214	49.65
	monochorionic	27	6.3	8	1.86	19	4.41
Outcome	excellent	208	25.1	99	22.97	109	25.29
	intermediate	157	19.0	64	14.85	93	21.58
	bad	66	8.0	35	8.12	31	7.19