. 2016 Dec 2;11(12):e0166952. doi: 10.1371/journal.pone.0166952

Table 3. Mean difference (95% confidence interval) in offspring BMI at various ages, if the father began smoking before 11 years old.

	All ages, adjusted	Offspring 12–19	Offspring 20–27	Offspring 28–35	Offspring 36–76
Sons and daughters
N_raw	221 / 46,831	44 / 12,418	63 / 13,281	66 / 11,950	48 / 9,182
N_sw	112.5 / 25,469	35 / 9,473	46 / 10,157	43 / 8,927	33 / 6,568
MD (95% CI)	0.58 (-0.11, 1.26)	0.76 (-0.40, 1.92)	0.26 (-0.81, 1.33)	0.48 (-0.68, 1.63)	1.73 (0.38, 3.08)
P	0.098	0.199	0.633	0.417	0.012
P_interaction	0.427	0.230	0.007	0.592	0.130
Sons
N_raw	113 / 23,758	23 / 6,201	31 / 6,489	31 / 6,107	28 / 4,961
N_sw	77 / 17,165	19 / 5,469	29 / 5,601	24 / 5,247	22 / 4,079
MD (95% CI)	0.22 (-0.53, 0.97)	-0.18 (-1.75, 1.39)	-1.23 (-2.44, -0.02)	0.12 (-1.22, 1.46)	2.00 (0.54, 3.47)
P	0.570	0.820	0.046	0.864	0.007
Daughters
N_raw	108 / 23,073	21 / 6,217	32 / 6,792	35 / 5,843	20 / 4,221
N_sw	73.5 / 16,765	21 / 5,386	24 / 5,915	28 / 5,025	17 / 3,560
MD (95% CI)	0.97 (0.06, 1.87)	1.50 (0.00, 3.00)	1.45 (-0.14, 3.05)	0.74 (-0.84, 2.32)	0.15 (-1.93, 2.23)
P	0.036	0.050	0.074	0.358	0.886

Linear regressions were adjusted for eldest offspring status, mother's and father's education level and father's employment type. Observations in all analyses were weighted by the reciprocal of the number of siblings (of the specified sex and age) used in that analysis, and N_sw is the sum of weights for those whose fathers began smoking before 11 years old, followed by the total sum of weights. N_raw are the unweighted sample sizes. One father of two daughters reported different onset ages in the first HUNT wave following each birth, giving rise to the non-integer N_sw among cases. The analysis of all offspring ages was additionally adjusted for a cubic spline of offspring age. P_interaction tests whether the MD differs between sons and daughters.