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Table 3 Relative risk ratios (RRR) from multinomial logistic regression and 95% confidence intervals (CI) of ASD and Non-TD (versus TD) in relation to phthalate metabolite concentrations (μg/L) during mid- to late pregnancy

From: Prenatal exposure to phthalates and autism spectrum disorder in the MARBLES study

  ASD versus TD Non-TD versus TD
RRR a 95% CI RRR a 95% CI
Average exposure during the 2nd and 3rd trimesters (n = 201; TD = 100, ASD = 46, Non-TD = 55)
MEP 1.23 (0.81, 1.85) 1.38 (1.01, 1.90)*
MiBP 0.64 (0.37, 1.12) 1.18 (0.72, 1.94)
MHiBP 0.64 (0.35, 1.19) 1.10 (0.64, 1.90)
MBP 0.87 (0.45, 1.69) 1.48 (0.86, 2.53)
MHBP 0.91 (0.44, 1.89) 1.35 (0.77, 2.37)
MBzP 0.83 (0.53, 1.31) 1.31 (0.90, 1.90)
MCPP 0.71 (0.47, 1.06) 1.43 (0.95, 2.14)#
MCOP 0.76 (0.53, 1.11) 1.29 (0.89, 1.87)
MCNP 0.92 (0.61, 1.39) 1.38 (0.96, 1.97)#
ΣDEHP b 0.75 (0.43, 1.32) 1.36 (0.88, 2.08)
Analysis restricted to samples collected during the 2nd trimester (n = 134; TD = 66, ASD = 29, Non-TD = 39)
MEP 0.95 (0.61, 1.47) 1.34 (0.85, 2.10)
MiBP 0.53 (0.23, 1.19) 0.81 (0.40, 1.60)
MHiBP 0.56 (0.25, 1.21) 0.72 (0.33, 1.53)
MBP 0.48 (0.19, 1.16) 0.81 (0.42, 1.56)
MHBP 0.54 (0.24, 1.21) 0.82 (0.42, 1.59)
MBzP 0.75 (0.42, 1.32) 1.31 (0.79, 2.15)
MCPP 0.53 (0.32, 0.87)* 1.31 (0.83, 2.07)
MCOP 0.68 (0.46, 1.00) 1.21 (0.77, 1.87)
MCNP 0.79 (0.49, 1.25) 1.24 (0.80, 1.91)
ΣDEHP b 0.81 (0.45, 1.42) 1.14 (0.71, 1.82)
Analysis restricted to samples collected during the 3rd trimester (n = 190; TD = 97, ASD = 43, Non-TD = 50)
MEP 1.30 (0.84, 1.98) 1.27 (0.92, 1.72)
MiBP 0.60 (0.33, 1.08) 1.21 (0.73, 1.98)
MHiBP 0.60 (0.32, 1.10) 1.10 (0.63, 1.92)
MBP 1.11 (0.55, 2.21) 1.54 (0.93, 2.55)
MHBP 1.32 (0.67, 2.59) 1.52 (0.88, 2.60)
MBzP 0.94 (0.61, 1.43) 1.33 (0.92, 1.92)
MCPP 0.86 (0.58, 1.28) 1.17 (0.80, 1.69)
MCOP 0.85 (0.59, 1.20) 1.01 (0.71, 1.42)
MCNP 0.90 (0.59, 1.35) 1.19 (0.82, 1.70)
ΣDEHP b 0.83 (0.44, 1.54) 1.28 (0.83, 1.94)
  1. aAdjusted for pre-pregnancy BMI, year of birth (linear and squared terms), and homeownership
  2. For a binary outcome, odds ratios would correspond to relative risk ratios (RRRs). In either case, ratios of relative risks are being described, with the relative risk being equal to the probability of having the stated level of the outcome divided by the probability of having the reference level of the outcome. The metabolites were measured in μg/L and were then natural log-transformed. Hence, the RRR corresponds to how much the relative risk changes (relatively) for a 2.72-fold increase in the metabolite concentration
  3. bBecause correlations among DEHP metabolites were high (r = 0.84–0.99), the molar sum of DEHP metabolites was only examined (ΣDEHP, μmol/L)
  4. *p-value < 0.05, # p-value < 0.10
  5. Note: MNP was excluded from this table because approximately 50% of samples had detectable concentrations. See Table 2 for abbreviations