Association of total lifetime breastfeeding duration with midlife handgrip strength: findings from Project Viva

BMC Women's Health

Table 2 Associations of lifetime breastfeeding duration (BFD) with dominant and nondominant handgrip strength, kg

	Model 1 β (95% CI)	Model 2 β (95% CI)	Model 3 β (95% CI)	Model 4 β (95% CI)
Dominant hand
Exposure
Lifetime BFD, per 3 months	0.09 (0.01, 0.16)	0.09 (0.02, 0.17)	0.10 (0.02, 0.18)	0.15 (0.03, 0.28)
Lifetime BFD, Quartiles
Q1	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Q2	0.23 (− 1.10, 1.57)	− 0.34 (− 1.78, 1.09)	− 0.33 (− 1.76, 1.10)	0.17 (− 1.86, 2.19)
Q3	1.28 (− 0.05, 2.61)	0.98 (− 0.45, 2.41)	0.96 (− 0.47, 2.38)	1.18 (− 0.99, 3.35)
Q4	1.31 (− 0.03, 2.64)	1.34 (− 0.10, 2.78)	1.41 (− 0.03, 2.84)	2.33 (0.10, 4.56)
Trend-p*	0.021	0.021	0.017	0.027
Average BFD per live birth, per 3 months	0.08 (− 0.09, 0.25)	0.13 (− 0.06, 0.31)	0.15 (− 0.03, 0.34)	0.16 (− 0.12, 0.43)
Nondominant hand
Exposure
Lifetime BFD, per 3 months	0.09 (0.02, 0.16)	0.10 (0.03, 0.17)	0.10 (0.03, 0.18)	0.15 (0.03, 0.26)
Lifetime BFD, Quartiles
Q1	0.0 (ref)	0.0 (ref)	0.0 (ref)	0.0 (ref)
Q2	0.47 (− 0.77, 1.71)	0.05 (− 1.28, 1.37)	0.06 (− 1.26, 1.39)	− 0.21 (− 2.08, 1.66)
Q3	1.37 (0.13, 2.61)	1.22 (− 0.11, 2.54)	1.19 (− 0.13, 2.51)	0.94 (− 1.07, 2.94)
Q4	1.58 (0.33, 2.82)	1.75 (0.41, 3.08)	1.81 (0.48, 3.14)	2.50 (0.43, 4.56)
Trend-p*	0.005	0.003	0.002	0.010
Average BFD per live birth, per 3 months	0.13 (− 0.03, 0.29)	0.18 (0.01, 0.35)	0.20 (0.03, 0.37)	0.23 (− 0.03, 0.49)

^*Trend p values across quartiles with quartiles coded as 1–2–3–4
Median, interquartile range (IQR) and range (min–max) of quartiles: Q1: 2 months (IQR: 0–5 months, range: 0–7 months), Q2: 12 months (IQR: 9.8–13 months, range 8–17 months), Q3: 24 months (IQR: 20–26 months, range 18–30 months), Q4: 42 months (IQR: 36–57 months, range 31–100 months)
Model 1. Unadjusted
Model 2. Adjusted for race/ethnicity, education, marital status, ever smoking, household income at enrollment, and age at 1st pregnancy
Model 3. Model 2 + age at handgrip strength measurement (precision variable)
Model 4. Model 3 + 1st trimester AHEI-P (continuous, units) and pre-pregnancy total PA (continuous, hours/week) (Restricted to women who were nulliparous at index pregnancy, N = 304, see Additional file 3: Table S2 for βs for Model 1–3 for nulliparious women only)
Bold indicates statistical significance
A participant's average lifetime BFD per live birth was calculated by taking their total lifetime BFD in months and dividing by their number of live births

ISSN: 1472-6874