Table 1.
Characteristics of Participants in the Early Determinants of Mammographic Density Study From Prepregnancy in Mothers to Midlife in Offspring, 1959–2008
| Characteristic | Daughter's BMIa in Midlife (Age 40 Years) | Sibling Study | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| BMI <25 (n = 486) | BMI ≥25 (n = 622) | P Valueb | Lighter Adult Sibling (n = 246) | Heavier Adult Sibling (n = 246) | rc | P Value | |||||
| Median (IQR) | % | Median (IQR) | % | Median (IQR) | % | Median (IQR) | % | ||||
| Maternal factors | |||||||||||
| Prepregnancy BMI | 21.75 (3.32) | 23.02 (4.92) | <0.001 | 22.13 (3.63) | 21.95 (3.77) | 0.90 | 0.15 | ||||
| Gestational weight gain, kg | 9.07 (4.54) | 9.53 (4.54) | 0.02 | 8.57 (4.15) | 9.19 (4.00) | 0.48 | 0.01 | ||||
| Smoking during pregnancy | 39 | 42 | 0.26 | 41 | 44 | 0.71 | 0.40 | ||||
| Infant characteristics | |||||||||||
| Gestational age, weeks | 40 (2) | 40 (2) | 0.63 | 40 (2) | 40 (2) | 0.22 | 0.17 | ||||
| Birth weight, g | 3,430 (766) | 3,459 (822) | 0.39 | 3.29 (0.57) | 3.26 (0.57) | 0.48 | 0.29 | ||||
| Birth length, cm | 51.00 (3.81) | 51.00 (3.81) | 0.79 | 50.80 (2.54) | 50.80 (3.07) | 0.29 | 0.90 | ||||
| Childhood growth | |||||||||||
| Weight, g | |||||||||||
| At age 4 months | 6,413 (999) | 6,430 (1,070) | 0.23 | 6,268 (988) | 6,190 (913) | 0.49 | 0.09 | ||||
| At age 1 year | 9,531 (1,536) | 9,752 (1,620) | <0.01 | 9,503 (1,598) | 9,429 (1,559) | 0.47 | 0.67 | ||||
| At age 4 years | 15,884 (2,556) | 16,830 (2,839) | <0.0001 | 15,843 (2,576) | 16,278 (2,669) | 0.58 | 0.09 | ||||
| Height, m | |||||||||||
| At age 4 months | 62.39 (3.37) | 62.38 (3.51) | 0.68 | 61.78 (3.28) | 61.63 (2.96) | 0.38 | 0.71 | ||||
| At age 1 year | 73.60 (3.58) | 74.19 (4.22) | 0.01 | 73.51 (3.85) | 73.81 (3.46) | 0.44 | 0.81 | ||||
| At age 4 years | 99.58 (6.57) | 101.00 (6.00) | <0.001 | 100.06 (6.31) | 99.67 (6.90) | 0.66 | 0.65 | ||||
| Demographic characteristics | |||||||||||
| Race/ethnicity (black or other) | 12 | 21 | <0.001 | ||||||||
| Maternal education (less than high school) | 20 | 29 | <0.001 | ||||||||
| Geographic site (Boston, Massachusetts) | 50 | 50 | 0.81 | ||||||||
| Midlife characteristics | |||||||||||
| Age at follow-up, years | 44 (2.7) | 44.2 (2.5) | 0.28 | 44 (2.8) | 43.9 (2.9) | 0.16 | 0.71 | ||||
| Mean BMI at follow-up | 22.1 (3.0) | 29.6 (7.0) | <0.001 | 23.6 (5.8) | 28.8 (8.6) | 0.67 | <0.001 | ||||
| Daughter's education (high school diploma or less) | 14 | 23 | <0.001 | 16 | 15 | 0.27 | 0.68 | ||||
| Daughter's parity (parous) | 86 | 88 | 0.31 | 88 | 85 | 0.15 | 0.12 | ||||
Abbreviations: BMI, body mass index; IQR, interquartile range.
a Weight (kg)/height (m)2.
b Midlife BMI groups were compared using the Kruskal-Wallis test.
c Pearson correlation coefficient, except for ranked variables, for which the Spearman correlation coefficient is presented.