A parsimonious explanation for intersecting perinatal mortality curves: understanding the effects of race and of maternal smoking

Table 2 Numbers and Rates of Live Births, Stillbirths and Neonatal Deaths among Singletons Births, Blacks, United States, 1997.

Gestational age	Stillbirths	Live births	Neonatal deaths	Stillbirth rate (1)*	Perinatal mortality rate (1)*	Neonatal mortality rate (1)*	Fetuses-at-risk	Stillbirth rate (2)*	Perinatal mortality rate (2)*	Neonatal mortality rate (2)*
32	222	5,354	55	39.8	47.2	10.3	558,038	0.40	0.47	0.10
33	179	7,552	69	23.2	28.6	9.1	552,462	0.32	0.40	0.12
34	251	11,994	61	20.5	24.3	5.1	544,731	0.46	0.55	0.11
35	211	18,277	53	11.4	13.3	2.9	532,486	0.40	0.46	0.10
36	233	28,729	93	8.0	10.2	3.2	513,998	0.45	0.57	0.18
37	251	50,631	101	4.9	6.1	2.0	485,036	0.52	0.64	0.21
38	233	90,553	126	2.6	3.4	1.4	434,154	0.54	0.72	0.29
39	241	126,796	142	1.9	2.6	1.1	343,368	0.70	0.95	0.41
40	172	113,151	104	1.5	2.1	0.9	216,331	0.80	1.09	0.48
41	85	58,386	65	1.5	2.1	1.1	103,008	0.83	1.18	0.63
≥42†	85	44,452	58	1.9	2.6	1.3	44,537	1.91	2.65	1.30
Total ‡	4,760	579,956	2,725	8.1	11.5	4.7	584,716	8.14	11.5	4.66

* 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 neonatal mortality rates (1). Stillbirth, perinatal (stillbirths plus early neonatal deaths) and neonatal mortality rates (2) were calculated using fetuses-at-risk as the denominator (see text). All rates are expressed per 1,000. † This period of risk exceeds 1 week and partly explains the large increase in the perinatal mortality (2). ‡ All gestational ages, including those <32 weeks and those with missing gestational age.

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