. Author manuscript; available in PMC: 2019 Aug 13.

Published in final edited form as: Lancet Child Adolesc Health. 2019 Apr 5;3(6):408–417. doi: 10.1016/S2352-4642(19)30108-7

Table 3.

Interactions between gestational age at birth and sex in relation to all-cause mortality at ages 0–45 years.

	Gestational age at birth						HRs (95% CI) for early term vs. full-term within sex strata^b	HRs (95% CI) for preterm vs. full-term within sex strata^b
	Full-term (39–41 wks)		Early term (37–38 wks)		Preterm (<37 wks)

	Rate^a	HR (95% CI)^b	Rate^a	HR (95% CI)^b	Rate^a	HR (95% CI)^b
Sex
Female	24·82	Reference	33·73	1·40 (1·34, 1·46)	153·31	6·13 (5·88, 6·40)	1·40 (1·34, 1·46)	6·13 (5·88, 6·40)
Male	41·79	1·68 (1·64, 1·73)	53·69	2·18 (2·10, 2·27)	188·78	7·49 (7·22, 7·77)	1·30 (1·25, 1·34)	4·45 (4·30, 4·60)

HRs (95% CI) for male vs. female within gestational age strata^b		1·68 (1·64, 1·73)		1·56 (1·49, 1·64)		1·22 (1·17, 1·28)
Interaction on additive scale: RERI (95% CI)			0·10 (0·01, 0·19); P=0·03		0·67 (0·36, 0·98); P<0·001
Interaction on multiplicative scale: HR ratio (95% CI)			0·93 (0·88, 0·98); P=0·008		0·73 (0·69, 0·76); P<0·001

Mortality rate per 100,000 person-years.

Adjusted for birth year, birth order, maternal age, maternal education, and maternal smoking. All HRs had P<0·001.

HR = hazard ratio, RERI = relative excess risk due to interaction