Skip to main content
. Author manuscript; available in PMC: 2019 May 1.
Published in final edited form as: Environ Int. 2019 Mar 7;126:533–542. doi: 10.1016/j.envint.2019.01.063

Table 2.

Adjusted parameter estimates for the change in placental growth measures (weight, efficiency, chorionic plate area and eccentricity) with each unit increase in term placental biopsy metal concentration (ng/g), stratified by infant sex and placental zinc and selenium concentrations.

Model Stratification Element Placenta weight (g) Placenta efficiency Chorionic disc area Eccentricity
β p-Value β p-Value β p-Value β p-Value
NONE As −2.80 (−9.35, 3.75) 0.4018 −0.0004 (−0.001, 0.001) 0.5183 1.83 (−1.39, 5.04) 0.2645 −0.0018 (−0.0081, 0.0045) 0.5755
(N=868) Cd −7.80 (−15.42, −2.48) 0.0009 −0.0012 (−0.0020, −0.0004) 0.0026 −1.94 (−4.21, 0.34) 0.0946 0.0023 (−0.0022, 0.0067) 0.3213
Hg −1.80 (−5.65, 2.20) 0.1495 −0.0002 (−0.0006, 0.0002) 0.2554 −0.25 (−1.45, 0.96) 0.6846 −0.0002 (−0.0026, 0.0022) 0.8683
Pb 2.49 (−1.74, 6.69) 0.1083 0.0005 (0.0000, 0.0010) 0.0498 0.28 (−1.21, 1.78) 0.7123 −0.0026 (−0.0055, 0.0004) 0.0865
Infant sex: As −8.68 (−19.20, 1.84) 0.1058 −0.0012 (−0.003, 0.000) 0.1633 −0.31 (−5.35, 4.72) 0.9023 −0.0004 (−0.0101, 0.0094) 0.9433
Female (N=495) Cd −8.95 (−15.42, −2.48) 0.0068 −0.0013 (−0.0023, −0.0003) 0.0140 −2.25 (−5.37, 0.86) 0.1560 0.0052 (−0.0007, 0.0112) 0.0861
Hg −1.73 (−5.65, 2.20) 0.3880 −0.0003 (−0.0009, 0.0003) 0.3103 −0.43 (−2.31, 1.45) 0.6527 −0.0005 (−0.0041, 0.0031) 0.7820
Pb 2.48 (−1.74, 6.69) 0.2486 0.0005 (−0.0002, 0.0011) 0.1706 −0.48 (−2.49, 1.53) 0.6401 −0.0024 (−0.0063, 0.0015) 0.2330
Male (N=498) As 2.43 (−5.78, 10.63) 0.5616 0.0003 (−0.001, 0.002) 0.7016 3.73 (−0.42, 7.88) 0.0780 −0.0023 (−0.0106, 0.0060) 0.5893
Cd −6.09 (−12.80, 0.06) 0.0751 −0.0009 (−0.0021, 0.0003) 0.1490 −2.20 (−5.61, 1.21) 0.2045 −0.0004 (0.0072, 0.0064) 0.9046
Hg −1.56 (−4.66, 1.43) 0.3212 −0.0001 (−0.0007, 0.0004) 0.6500 −0.12 (−1.69, 1.46) 0.8851 0.0003 (−0.0028, 0.0034) 0.8490
Pb 2.33 (−2.16, 6.83) 0.3075 0.0006 (−0.0002, 0.0014) 0.1519 1.47 (−0.81, 3.74) 0.2049 −0.0034 (−0.0079, 0.0012) 0.1474
Median Zn: As −0.97 (−10.18, 8.25) 0.8366 0.0001 (−0.001, 0.002) 0.8477 2.12 (−2.55, 6.75) 0.3701 0.0001 (−0.0092, 0.0095) 0.9777
Below (N=501) Cd −8.81 (−16.85, −0.76) 0.0320 −0.0017 (−0.0031, −0.0004) 0.0124 −0.15 (−4.23, 3.93) 0.9407 0.0057 (−0.0024, 0.0138) 0.1702
Hg −0.60 (−4.22, 3.03) 0.7460 0.0001 (−0.0005, 0.0007) 0.8171 −0.36 (−2.18, 1.46) 0.6983 −0.0003 (−0.0047, 0.0041) 0.2546
Pb 2.42 (−2.63, 7.47) 0.3468 0.0006 (−0.0002, 0.0014) 0.1581 0.55 (−2.00, 3.09) 0.6731 −0.0025 (−0.0066, 0.0015) 0.6502
Above (N=502) As −3.60 (−13.06, 5.86) 0.4545 −0.0008 (−0.002, 0.001) 0.3173 1.94 (−2.58, 6.47) 0.3987 −0.0022 (−0.0108, 0.0064) 0.6202
Cd −5.14 (−11.99, 1.71) 0.141 −0.0008 (−0.0019, 0.0002) 0.1336 −3.10 (−6.05, −0.15) 0.0398 0.0012 (−0.0044, 0.0069) 0.6755
Hg −3.06 (−6.43, 0.31) 0.0754 −0.0005 (−0.0011, 0.0001) 0.1046 −0.33 (−1.95, 1.29) 0.6870 −0.0003 (−0.0047, 0.0041) 0.4005
Pb 2.96 (−0.95, 6.86) 0.1375 0.0006 (−0.0001, 0.0012) 0.1064 0.10 (−1.78, 1.97) 0.9171 −0.0025 (−0.0066, 0.0015) 0.1529
Median Se: As −1.38 (−9.90, 7.14) 0.7507 0.0001 (−0.013, 0.001) 0.9228 1.54 (−2.82, 5.91) 0.4874 −0.0001 (−0.0091, 0.0088) 0.9763
Below (N=505) Cd −13.20 (−20.70, −5.70) 0.0006 −0.0022 (−0.0034, −0.0009) 0.0008 −1.00 (−4.89, 2.88) 0.6117 0.0008 (−0.0072, 0.0087) 0.8514
Hg −2.67 (−5.59, 0.25) 0.0726 −0.0003 (−0.0008, 0.0002) 0.2114 −0.25 (−1.75, 1.25) 0.7448 −0.0011 (−0.0042, 0.0020) 0.4854
Pb 0.32 (−3.48, 4.12) 0.8691 0.0001 (−0.0056, 0.0007) 0.8680 −0.33 (−2.27, 1.62) 0.7424 −0.0029 (−0.0069, 0.0011) 0.1602
Above (N=506) As −6.04 (−16.41, 4.34) 0.2533 −0.0012 (−0.003, 0.001) 0.2100 1.60 (−3.16, 6.37) 0.5083 −0.0039 (−0.0126, 0.0048) 0.3766
Cd −5.12 (−11.26, 1.03) 0.1023 −0.0008 (−0.0019, 0.0003) 0.1411 −1.67 (−4.51, 1.17) 0.1814 0.0025 (−0.0027, 0.0077) 0.3515
Hg −0.38 (−4.94, 4.17) 0.6880 −0.0002 (−0.0010, 0.0006) 0.6194 0.12 (−1.97, 2.21) 0.9104 0.0004 (−0.0034, 0.0042) 0.8321
Pb 6.50 (1.39, 11.60) 0.0127 0.0013 (0.0004, 0.0022) 0.0032 1.33 (−1.03, 3.68) 0.2689 −0.0017 (−0.0060, 0.0026) 0.4357

Models adjusted for maternal pre-pregnancy BMI (continuous), maternal education level (ordinal, with five categories listed in Table 1, assigned values of 1–5 respectively, gestational age (continuous), parity (continuous), maternal age at enrollment (continuous) and maternal exposure to cigarette smoke before or during pregnancy (ordinal, with three categories, where 0 is never exposed; 1 is exposed before pregnancy and 2 is continued to smoke during pregnancy) p<0.05 in bold type. Placental weight data was missing for 164 participants, and measures of maximum placental diameter were missing for 163 participants, measures of minimum and maximum placental diameter were missing for 166 participants and birthweight measures were missing for 21 participants