Birth Defects in Singleton versus Multiple ART Births in Japan (2004–2008)

Table 3

Crude percentage of birth defects in ART live-born babies according to plurality.

Year	Singletons	Multiples	RR (95% CI)	Total
2004	0.54 (69/12,851)^a	0.51 (27/5,317)^a	0.95 (0.61–1.47)^a	0.52 (96/18,168)
	0.55 (69/12,562^)b	0.48 (27/5,606)^b	0.88 (0.56–1.37)^b
2005	0.67 (91/13,601)^a	0.60 (33/5,511)^a	0.90 (0.60–1.33)^a	0.65 (124/19,112)
	0.68 (91/13,324)^b	0.57 (33/5,788)^b	0.83 (0.56–1.24)^b
2006	0.94 (140/14,876)^a	1.04 (49/4,711)^a	1.11 (0.80–1.53)^a	0.96 (190/19,587)
	0.96 (140/14,649)^b	0.99 (49/4,938)^b	1.04 (0.75–1.44)^b
2007	1.28 (200/15,681)	1.43 (56/3,914)	1.12 (0.84–1.51)	1.32 (258/19,595)
2008	1.39 (264/19,034)	1.69 (45/2,670)	1.22 (0.89–1.66)	1.43 (310/21,704)
Total	1.00 (764/76,043)^a	0.95 (210/22,123)^a	0.94 (0.81–1.10)^a	0.99 (978/98,166)^c
	1.02 (764/75,250)^b	0.92 (210/22,916)^b	0.90 (0.78–1.05)^b

Numbers of ART live births according to plurality from 2004 to 2006 were estimated by the present author using JSOG annual report.
Numbers of ART live births according to plurality from 2007 to 2008 were presented in the JSOG annual report.
^aMinimum estimation of numbers of multiples.
^bMaximum estimation of numbers of multiples.
^cTotal number includes four subjects with unknown plurality.