Table 3.
Adjusteda models of maternal perfluoroalkyl substance serum concentrations (ng/mL) and absolute gestational weight gain, stratified by pre-pregnancy BMI, in the Avon Longitudinal Study of Parents and Children sub-study population (N = 905).
| Model | Coefficientb | 95% CI | Hetero- geneity p-value |
I2 statisticc | |
|---|---|---|---|---|---|
| PFOA | Underweight | 0.06 | −0.14, 0.26 | 0.32 | 0.0% |
| Normal weight | −0.01 | 0.49 | 0.0% | ||
| Overweight | −0.03 | −0.33, 0.26 | 0.69 | 0.0% | |
| Obese | −0.29 | −0.65, 0.08 | 0.40 | 0.0% | |
| PFOS | Underweight | 0.02 | −0.24, 0.28 | 0.78 | 0.0% |
| Normal weight | −0.03 | −0.13, 0.06 | 0.89 | 0.0% | |
| Overweight | −0.04 | −0.29, 0.21 | 0.10 | 62.4% | |
| Obese | −0.07 | −0.36, 0.22 | 0.29 | 12.1% | |
| PFHxS | Underweight | 0.01 | −0.12, 0.13 | 0.42 | 0.0% |
| Normal weight | 0.01 | −0.05, 0.07 | 0.34 | 0.0% | |
| Overweight | 0.11 | −0.03, 0.25 | 0.96 | 0.0% | |
| Obese | 0.02 | −0.15, 0.19 | 0.38 | 0.0% | |
| PFNA | Underweight | 0.24 | 0.00, 0.48 | 0.80 | 0.0% |
| Normal weight | 0.07 | 0.00, 0.15 | 0.04 | 76.0% | |
| Overweight | −0.07 | −0.28, 0.13 | 0.17 | 48.1% | |
| Obese | −0.34 | −0.99, 0.30 | 0.60 | 0.0% |
Abbreviations: N, number; CI, confidence interval.
Adjusted for maternal education, prenatal smoking, maternal age at delivery, parity, pre-pregnancy BMI, gestational age at delivery, and gestational age at sample.
Coefficient representing a 10% increase in the PFAS of interest.
The I2 statistic indicates the percentage of variance in a meta-analysis that is attributable to study heterogeneity rather than chance. It is calculated using 100% × (Q − df)/Q where Q is the Cochran’s heterogeneity statistic, which is chi-square distributed [45].