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. 2016 Oct 12;18:102. doi: 10.1186/s13058-016-0751-z

Table 2.

Mutually adjusted associations of MRI percent water in daughters with maternal characteristics and markers of in utero exposures estimated using the complete and imputed data

Relative change in MRI percent water, geometric mean (95 % CI)
Complete dataa Imputed datab
Maternal characteristicsc n = 303 n = 490
 At participant’s birth only
  Mother’s age at menarche (per 1 SD 1.5 years) 0.98 (0.96–1.01) 1.00 (0.98–1.01)
  Age mother first used OC (per 1 SD 3.1 years) 1.00 (0.98–1.02) 1.00 (0.98–1.02)
  Mother’s height (per 1 SD 6.5 cm) 1.02 (1.00–1.04) 1.03 (1.01–1.05)
  Mother’s age at first birth (per 1 SD 4.7 years) 0.99 (0.96–1.03) 0.98 (0.96–1.01)
  Mother’s age at participant’s birth (per 1 SD 4.5 years) 1.00 (0.96–1.03) 1.01 (0.98–1.03)
  Mother’s pre-pregnancy BMI (per 1 SD 3.0 kg/m2) 1.01 (0.99–1.03) 1.01 (0.99–1.03)
 Mother’s parity at participant’s birth
  0 1 (ref) 1 (ref)
  1 1.04 (0.99–1.10) 1.02 (0.98–1.06)
  2+ 1.00 (0.93–1.08) 1.00 (0.95–1.06)
 Mother had a history of breast cancer
  No 1 (ref) 1 (ref)
  Yes 1.01 (0.95–1.08) 1.01 (0.96–1.07)
Maternal characteristics at participant’s birth and at mammographyd
 Mother’s MPD (per 1 SD 13.4 %) 1.06 (1.01–1.10)
In utero exposurese n = 107 n = 490
 Placental weight (per 1 SD 133.5 g) 1.03 (0.99–1.07) 1.03 (0.99–1.07)
 Absolute GWG, week 0 to delivery (per 1 SD 3.9 kg) 0.97 (0.93–1.01) 1.00 (0.98–1.02)
 Mother drank alcohol during pregnancy (%)
  No 1 (ref) 1 (ref)
  Yes 1.01 (0.91–1.11) 1.00 (0.95–1.06)
 Mother smoked during pregnancy (%)
  No 1 (ref) 1 (ref)
  Yes 0.95 (0.89–1.03) 0.99 (0.96–1.04)

Abbreviations: MRI Magnetic resonance imaging, BMI Body mass index, GWG Gestational weight gain, OC Oral contraceptives, MPD Mammographic percent density ref Reference category

MRI breast measurements were log-transformed, and exponentiated estimated regression parameters, with 95 % CIs calculated by exponentiating the original 95 % CIs, are presented. Bold indicates 95 % CI do not cross the null (1.00)

aAnalysis restricted to those with non-missing data for all variables included in the models

bSee Statistical methods section in main text

cMaternal and confounding factors (age, BMI and menstrual phase/hormonal contraceptive use at MRI) were included in the model simultaneously

dAnalysis restricted to the subset of participants for whose mothers it was possible to retrieve a mammogram (n = 116). Model includes all the maternal characteristics at the participant’s birth listed in the table as well as maternal MPD in later life (mean age at mammography 52.8 years; Table 1), adjusting for the daughters’ age, BMI and menstrual phase at the time of MRI and for the mothers’ age and BMI at the time of mammography

eIn utero and confounding factors (age, BMI and menstrual phase/hormonal contraceptive use at the time of MRI) were included in the model simultaneously