A parsimonious explanation for intersecting perinatal mortality curves: understanding the effect of plurality and of parity

Table 1 Numbers and rates of live births, stillbirths and early neonatal deaths among singletons births, Canada (excluding Ontario), 1991 to 1997.

Gestational age	Stillbirths	Live births	Early neonatal deaths	Stillbirth rate (1)†	Early neonatal death rate (1)†	Perinatal mortality rate (1)†	Fetuses at risk	Stillbirth rate (2)†	Early neonatal death rate (2)†	Perinatal mortality rate (2)†
32	288	4,287	125	63.0	29.2	90.3	1,593,933	0.2	0.1	0.3
33	314	5,758	118	51.7	20.5	71.1	1,589,358	0.2	0.1	0.3
34	329	10,661	144	29.9	13.5	43.0	1,583,286	0.2	0.1	0.3
35	318	18,128	138	17.2	7.6	24.7	1,572,296	0.2	0.1	0.3
36	439	41,962	194	10.4	4.6	14.9	1,553,850	0.3	0.1	0.4
37	451	87,566	186	5.1	2.1	7.2	1,511,449	0.3	0.1	0.4
38	552	232,039	252	2.4	1.1	3.5	1,423,432	0.4	0.2	0.6
39	522	356,922	235	1.5	0.7	2.1	1,190,841	0.4	0.2	0.6
40	601	536,302	331	1.1	0.6	1.7	833,397	0.7	0.4	1.1
41	304	245,665	152	1.2	0.6	1.9	296,494	1.0	0.5	1.5
≥42	92	50,433	58	1.8	1.2	3.0	50,525	1.8	1.2	3.0
Total‡	8,694	1,614,531	4,589	5.4	2.8	8.2	1,623,225	5.4	2.8	8.2

† Total births at each gestational week served as the denominator for stillbirth and perinatal mortality rates (1), while live births at each gestational week constituted the denominator for early neonatal death rates (1). Stillbirth, early neonatal death and perinatal mortality rates (2) were calculated using fetuses-at-risk as the denominator (see text). All rates are expressed per 1,000. ‡ All gestational ages, including those <32 weeks and those with missing gestational age.

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