Introduction
Methods
Study design and population
Dietary assessment
Kidney outcome assessments
Covariates
Statistical analysis
Results
Subject characteristics
Characteristics | All (n = 2968) | Tertiles of energy-adjusted total protein intake at age 1 year |
P valuea
| ||
---|---|---|---|---|---|
Tertile 1 (<37.5 g/day) (n = 989) | Tertile 2 (37.5–43.9 g/day) (n = 990) | Tertile 3 (>43.9 g/day) (n = 989) | |||
Maternal characteristics | |||||
Maternal age (year) | 31.5 (21.7–39.9) | 31.8 (22.5–41.4) | 31.9 (22.4–39.6) | 31.6 (20.6–39.4) | 0.01 |
Maternal body mass index at enrolment (kg/m2) | 23.4 (18.7–35.2) | 23.4 (18.8–34.7) | 23.6 (18.9–35.6) | 24.5 (18.5–37.1) | 0.50 |
Nulliparous (%) | 60.4 | 59.5 | 59.8 | 61.6 | 0.09 |
Education level (%) | 0.42 | ||||
Primary | 3.5 | 3.7 | 3.5 | 3.2 | |
Secondary | 33.9 | 33.2 | 32.8 | 35.6 | |
Higher | 62.7 | 63.1 | 63.7 | 61.2 | |
Folic acid supplement use (%) | 0.74 | ||||
Never | 15.8 | 17.0 | 14.8 | 15.4 | |
In the first 10 weeks of pregnancy | 30.2 | 28.5 | 30.9 | 31.3 | |
Periconceptional | 54.0 | 54.4 | 54.3 | 53.2 | |
Smoking during pregnancy (%) | 0.49 | ||||
Never | 78.1 | 78.7 | 78.6 | 77.0 | |
Until pregnancy was known | 10.0 | 9.2 | 9.4 | 11.5 | |
Continued | 11.8 | 12.1 | 11.9 | 11.5 | |
Child characteristics | |||||
Girls (%) | 50.9 | 51.6 | 52.6 | 48.5 | 0.17 |
Ethnicity (%) | 0.24 | ||||
Western | 76.9 | 75.5 | 78.1 | 77.0 | |
Cape Verdean | 2.0 | 1.8 | 1.8 | 2.3 | |
Moroccan | 3.2 | 2.8 | 2.8 | 4.1 | |
Netherlands Antillean | 1.7 | 2.3 | 1.9 | 1.1 | |
Turkish | 4.5 | 4.5 | 4.0 | 4.9 | |
Surinamese Creoles | 2.3 | 3.0 | 2.5 | 1.3 | |
Surinamese Hindustani | 2.2 | 2.6 | 1.9 | 2.2 | |
Other non-western | 7.1 | 7.5 | 6.9 | 7.0 | |
Gestational age at birth (weeks) | 40.0 (1.7) | 39.9 (1.9) | 39.9 (1.7) | 40.0 (1.6) | 0.79 |
Birth weight (g) | 3472 (551) | 3462 (562) | 3466 (557) | 3489 (532) | 0.51 |
Breastfeeding (%) | <0.01 | ||||
Exclusive ≥ 4 months | 29.5 | 34.8 | 26.9 | 27.2 | |
Partial ≥ 4 months | 62.5 | 58.1 | 65.5 | 63.7 | |
Never or ≤ 4 months | 8.0 | 7.1 | 7.5 | 9.1 | |
Child characteristics at dietary measurement | |||||
Age at FFQ (months) | 12.9 (12.2–18.9) | 12.8 (12.2–18.6) | 12.9 (12.2–18.7) | 13.0 (12.2–19.4) | <0.01 |
Total energy intake (kcal/ day) | 1266 (678–2212) | 1297 (619–2264) | 1238 (650–2093) | 1253 (765–2237) | 0.02 |
Protein intake (g/day)b
| |||||
Total protein | 41.2 (12.9) | 34.9 (10.8) | 39.7 (10.1) | 48.0 (12.1) | <0.01 |
Animal protein | 25.7 (10.3) | 20.8 (8.7) | 25.0 (8.1) | 33.1 (9.5) | <0.01 |
Vegetable protein | 14.9 (5.7) | 13.5 (5.4) | 14.8 (5.2) | 16.6 (5.9) | <0.01 |
Protein intake (E%) | |||||
Total protein | 12.9 (2.4) | 10.5 (1.1) | 12.9 (1.0) | 15.4 (1.7) | <0.01 |
Animal protein | 8.1 (2.4) | 6.2 (1.7) | 8.0 (1.6) | 10.2 (2.1) | <0.01 |
Vegetable protein | 4.6 (1.4) | 4.1 (1.3) | 4.7 (1.3) | 5.1 (1.3) | <0.01 |
Total fat intake (g/day)b
| 42.3 (17.5) | 43.1 (18.8) | 40.8 (16.0) | 42.7 (16.7) | <0.01 |
Sodium intake from foods (g/day)b
| 1.02 (0.35) | 0.88 (0.32) | 0.98 (0.30) | 1.17 (0.35) | <0.01 |
Television watching (h/day) | 0.9 (0.5) | 0.9 (0.5) | 0.9 (0.5) | 0.9 (0.5) | 0.19 |
Diet score | 4.2 (1.3) | 3.3 (1.1) | 4.1 (1.1) | 5.1 (1.2) | <0.01 |
Child characteristics at 6-year visit | |||||
Age (years) | 5.9 (5.6–6.6) | 5.9 (5.6–6.5) | 5.9 (5.6–6.6) | 5.9 (5.6–6.6) | 0.03 |
Height (cm) | 118.2 (5.2) | 117.8 (4.9) | 118.2 (5.4) | 118.5 (5.2) | 0.02 |
Weight (kg) | 22.4 (3.4) | 22.1 (3.1) | 22.4 (3.6) | 22.7 (3.5) | <0.01 |
Body mass index (kg/m2) | 16.0 (1.6) | 15.9 (1.5) | 16.0 (1.6) | 16.1 (1.7) | <0.01 |
Body surface area (kg/m2) | 0.86 (0.08) | 0.85 (0.07) | 0.86 (0.08) | 0.86 (0.08) | <0.01 |
Combined kidney volume (cm3) | 121 (21) | 119 (21) | 122 (23) | 122 (21) | <0.01 |
Creatinine (μmol/l) | 37.0 (5.2) | 37.2 (5.0) | 36.8 (5.4) | 36.8 (5.2) | 0.32 |
Cystatin C (mg/L) | 0.79 (0.08) | 0.79 (0.08) | 0.78 (0.08) | 0.78 (0.08) | 0.02 |
eGFRCreat (Schwartz) (mL/min per 1.73 m2) | 119 (16) | 118 (15) | 120 (17) | 120 (16) | 0.06 |
eGFRCysC (Zappitelli) (mL/min per 1.73 m2) | 102 (13) | 100 (13) | 102 (14) | 102 (13) | <0.01 |
Urinary albumin/creatinine ratio | 0.79 (0.20–5.70) | 0.83 (0.20–7.33) | 0.77 (0.190–5.56) | 0.77 (0.20–5.00) | 0.01 |
Microalbuminuria (%) | 7.1 | 7.6 | 7.5 | 6.3 | 0.49 |
Protein intake in early childhood and kidney outcomes at school age
Protein intake | Kidney volume (mm3) (n = 2755) | eGFRCreat (Schwartz 2009) (mL/min per 1.73 m2) (n = 2006) | eGFRCysC (Zappitelli 2006) (mL/min per 1.73 m2) (n = 2007) | ACR (% change)a (n = 2868) |
---|---|---|---|---|
Model 1b
| ||||
Tertile 1 | Reference | Reference | Reference | Reference |
Tertile 2 | 2.31 (0.61, 4.02)* | 1.90 (0.17, 3.63)* | 1.84 (0.44, 3.25)* | −6.8 (−14.6, 1.0) |
Tertile 3 | 1.16 (−0.54, 2.87) | 2.46 (0.73, 4.19)* | 1.75 (0.35, 3.15)* | −7.8 (−15.7, −0.1)* |
P
trend
c
| 0.17 | <0.01* | 0.01* | 0.04* |
Per 10 g | 0.29 (−0.67, 1.25) | 1.03 (0.04, 1.99)* | 0.66 (−0.12, 1.44) | −5.4 (−9.8, −1.1)* |
Model 2b
| ||||
Tertile 1 | Reference | Reference | Reference | Reference |
Tertile 2 | 2.33 (0.64, 4.03)* | 1.85 (0.12, 3.58)* | 1.84 (0.43, 3.25)* | −6.7 (−14.5, 1.1) |
Tertile 3 | 1.21 (−0.50, 2.91) | 2.28 (0.56, 4.00)* | 1.70 (0.30, 3.11)* | −6.9 (−14.8, 0.0)* |
P
trend
c
| 0.16 | <0.01* | 0.02* | 0.08 |
Per 10 g | 0.31 (−0.65, 1.27) | 0.91 (−0.05, 1.86) | 0.64 (−0.14, 1.43) | −4.9 (−9.3, −0.01)* |
Model 3b
| ||||
Tertile 1 | Reference | Reference | Reference | Reference |
Tertile 2 | 1.96 (0.10, 3.82)* | 1.21 (−0.69, 3.11) | 1.58 (−0.21, 3.33) | −3.1 (−11.7, 5.4) |
Tertile 3 | 0.36 (−1.91, 2.63) | 1.11 (−1.20, 3.42) | 1.60 (−0.28, 3.49) | −0.4 (−10.9, 10.0) |
P
trend
c
| 0.74 | 0.35 | 0.10 | 0.93 |
Per 10 g | −0.55 (−1.86, 0.76) | −0.17 (−1.49, 1.15) | 0.37 (−0.71, 1.45) | −2.0 (−8.0, 4.0) |