Changes in fetal and neonatal mortality during 40 years by offspring sex: a national registry-based study in Norway

Table 2 Absolute change (per 1000) and relative change in mortality from pregnancy week 23 to 1 month after birth by sex of child for non-immigrants in Norway, 1967–2005

	Absolute change				Relative change
	Coefficient	95% CI	Coefficient	95% CI	Coefficient	95% CI
Boy	24.094	23.567, 24.622	19.647	19.272, 20.002	1.245	1.191, 1.301
Girl	19.406	18.863, 19.949	15.958	15.583, 16.334	1.000
Boy * (Year - 1967)	−1.116	−1.183, -1.048	−0.466	−0.483,−0.449	0.956	0.954, 0.957
Girl * (Year-1967)	−0.867	−0.936, −0.798	−0.370	−0.387, −0.353	0.958	0.956, 0.960
Boy * (Year - 1967)²	0.017	0.015, 0.019
Girl * (Year - 1967)²	0.013	0.011, 0.015
Test for equal average trends for boys and girls:			p < 0.001		p = 0.132
N				1,974,811

Linear probability and logistic regression analyses. Pregnancies with gestational length >22.

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