Table 2.

Type of twinning according to mode of conception. Values are numbers (percentages) unless stated otherwise

	Natural conception group (n=2915)	Subfertility treatment group (n=1453)	P value
Monozygotic:	1347 (46.2)	70 (4.8)	<0.001
Monochorionic	885 (65.7)	56 (80.0)
Dichorionic	462 (34.3)	14 (20.0)
Dizygotic:	1568 (53.8)	1383 (95.2)	<0.001
Unlike sex*	776 (49.5)	688 (49.7)	0.9
Same sex, male	410 (26.1)	351 (25.4)
Same sex, female	382 (24.4)	344 (24.9)

^*Male-female or female-male twin pairs regardless of birth order.