Table 2.
The individual and combined effect of maternal folate concentrations and prepregnancy BMI categories on child BMI z-score and overweight or obesity at age 2–9 years (n=1517) in the Boston Birth Cohort (BBC)a
| Maternal | N | Child BMI z-score
|
Child overweight or obesity
|
|||
|---|---|---|---|---|---|---|
| BMI | Folate | Mean (SD) | β (95%CI) | Case, n(%) | OR (95%CI) | |
| Quartileb | ||||||
| Q4 | 379 | 0.61 (1.13) | ref | 132(34.8) | 1.00 | |
| Q3 | 380 | 0.57 (1.33) | −0.10 (−0.27 to 0.07) | 147(38.7) | 1.11 (0.82 to 1.52) | |
| Q2 | 379 | 0.57 (1.27) | −0.07 (−0.24 to 0.09) | 135(35.6) | 0.99 (0.72 to 1.35) | |
| Q1 | 379 | 0.89 (1.30) | 0.21 (0.04 to 0.38) | 176(46.4) | 1.50 (1.10 to 2.04) | |
| Folate per quartile decrease | 0.06 (0.01 to 0.12) | 1.12 (1.01 to 1.23) | ||||
| Binaryb | ||||||
| Q2–Q4 | 1138 | 0.58 (1.24) | ref | 414(36.4) | 1.00 | |
| Q1 | 379 | 0.89 (1.30) | 0.27 (0.13 to 0.41) | 176(46.4) | 1.45 (1.13 to 1.87) | |
| NL | 693 | 0.41 (1.25) | ref | 212(30.6) | 1.00 | |
| OWc | 443 | 0.71 (1.20) | 0.23 (0.09 to 0.37) | 185(41.8) | 1.49 (1.15 to 1.93) | |
| OBc | 381 | 1.06 (1.26) | 0.54 (0.39 to 0.70) | 193(50.7) | 2.03 (1.53 to 2.68) | |
| P for trend | <0.001 | <0.001 | ||||
| Combined effect | ||||||
| NL | Q2–Q4 | 527 | 0.35 (1.22) | ref | 151(28.7) | 1.00 |
| Q1 | 166 | 0.59 (1.31) | 0.20 (−0.01 to 0.41) | 61(36.7) | 1.35 (0.91 to 1.98) | |
| OW | Q2–Q4 | 333 | 0.65 (1.17) | 0.22 (0.06 to 0.38) | 131(39.3) | 1.45 (1.07 to 1.96) |
| Q1 | 110 | 0.90 (1.27) | 0.46 (0.21 to 0.70) | 54(49.1) | 2.13 (1.37 to 3.30) | |
| OB | Q2–Q4 | 278 | 0.95 (1.27) | 0.48 (0.30 to 0.65) | 132(47.5) | 1.90 (1.38 to 2.62) |
| Q1 | 103 | 1.37 (1.19) | 0.89 (0.63 to 1.15) | 61(59.2) | 3.05 (1.91 to 4.86) | |
| Stratified by BMI categories | ||||||
| NL | Q1 | 166 | 0.59 (1.31) | ref | 61(36.8) | 1.00 |
| Q2–Q4 | 527 | 0.35 (1.22) | −0.17 (−0.39 to 0.05) | 151(28.7) | 0.79 (0.53 to 1.19) | |
| OW | Q1 | 110 | 0.90 (1.27) | ref | 54(49.1) | 1.00 |
| Q2–Q4 | 333 | 0.65 (1.17) | −0.23 (−0.48 to 0.01) | 131(39.3) | 0.69 (0.43 to 1.09) | |
| OB | Q1 | 103 | 1.37 (1.19) | ref | 61(59.2) | 1.00 |
| Q2–Q4 | 278 | 0.95 (1.27) | −0.48 (−0.75 to −0.21) | 132(47.5) | 0.57 (0.34 to 0.95) | |
Abbreviation: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); NL, normal weight; OW, overweight; OB, obesity.
SI conversion factor: To convert folate to ng/mL, divided by 2.266.
The BBC uses a rolling enrollment; the study sample consists of children enrolled from 1998–2012 who have been followed from birth up to the last visit recorded by electronic medical record. Q2–Q4 folate concentration range: 20.37–185.51nmol/L, Q1 folate concentration range: 6.64–20.36 nmol/L. Maternal prepregnancy BMI was categorized into three groups: NL: BMI 18.5–24.9 kg/m2, OW: 25–29.9kg/m2, and OB: ≥30kg/m2.
Adjusted for maternal age, race, education, smoking, parity, perceived stress during pregnancy, diabetes, plasma vitamin B12 concentration during pregnancy, infant’s gestational age category, birthweight, and breastfeeding. There was no significant interaction between maternal folate status and prepregnancy obesity (p>0.05).
Also adjusted for maternal prepregnancy BMI category.
Additional adjustment for plasma folate concentration