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. Author manuscript; available in PMC: 2021 Jul 1.
Published in final edited form as: Stat Methods Med Res. 2019 Sep 23;29(7):1769–1786. doi: 10.1177/0962280219876963

Table 6:

The gestational-age-specific mortality risk and 95% confidence interval for girls born preterm (22 to 29 weeks) with normal birthweight (BW) and head circumference (HC) are shown in bold font. The other rows show the mortality relative risk (as compared to infants with normal BW and HC) and 95% confidence interval for infants with either one or both anthropometric measurements below the univariate 10th percentile. The sample size is denoted by N.

BW HC N Risk Lower Upper
(21, 23] weeks
Normal Normal 4,655 0.52 0.51 0.54
Normal < 10th 322 1.23 1.13 1.34
< 10th Normal 306 1.36 1.26 1.47
< 10th < 10th 213 1.50 1.39 1.61
(23, 25] weeks
Normal Normal 14,979 0.19 0.19 0.20
Normal < 10th 650 1.45 1.27 1.65
< 10th Normal 736 1.85 1.67 2.05
< 10th < 10th 1,033 2.69 2.51 2.88
(25, 27] weeks
Normal Normal 19,571 0.06 0.06 0.07
Normal < 10th 649 1.84 1.47 2.30
< 10th Normal 860 2.12 1.77 2.54
< 10th < 10th 1,368 4.19 3.77 4.65
(27, 29] weeks
Normal Normal 24,318 0.02 0.02 0.03
Normal < 10th 995 1.15 0.79 1.69
< 10th Normal 1,253 1.70 1.28 2.25
< 10th < 10th 1,531 3.83 3.21 4.58