Results

In total, 23 maternal-fetal pairs were enrolled: 18 in the birth defect group and five in the control group. Birth defects included cardiac and brain abnormalities. There were no significant differences in the demographic variables of age, body mass index, gravidity, parity, or gestational age between the group with a known birth defect and the controls (Table 1).

Birth defect | n (%) | Variable | Mean | SD | Minimum | Maximum
No | 5 (22) | Age | 27.4 | 6.1 | 23 | 37
BMI | 31.2 | 4.6 | 25 | 37
Gravida | 3.8 | 1.3 | 3 | 6
Parity | 2.6 | 0.9 | 2 | 4
Gestational age | 38.2 | 1.1 | 37 | 39.2
Yes | 18 (78) | Age | 26.9 | 4.4 | 21 | 39
BMI | 31.9 | 7.3 | 20 | 47
Gravida | 3.1 | 1.3 | 1 | 6
Parity | 1.6 | 1.0 | 0 | 4
Gestational age | 37.4 | 2.3 | 30 | 39.2

The birth defect group was more likely to have private, VA, or other insurance listed, but the majority of both groups had Medicaid/Medicare as their payer source (Table 2).

Insurance type | Birth defect
No | Yes | Total
Private | 1 | 4 | 5
Medicaid/Medicare | 4 | 11 | 15
Veteran affairs | 0 | 2 | 2
Other | 0 | 1 | 1
Total | 5 | 18 | 23

Regarding race, 3 (60%) patients in the control group and 11 (61%) patients in the birth defect group were Black (Table 3).

Race | Birth defect
No | Yes | Total
Black | 3 | 11 | 14
White | 1 | 7 | 8
Other | 1 | 0 | 1
Total | 5 | 18 | 23

For each of the essential elements we reviewed, we calculated both maternal and fetal levels (via cord blood). From this data, copper and zinc levels were higher in both maternal groups versus fetal levels (Figure 1). Copper levels were also found to be lower than expected, and zinc levels were higher than expected.

Figure 1: Copper, selenium, and zinc levels.BD = birth defect

Manganese levels were higher in fetal samples compared to non-anomalous infants and those with birth defects (Figure 2).

Figure 2: Calcium, manganese, and strontium levels.BD = birth defect

No associations between birth defects and toxic element levels were demonstrated in the study (Figure 3).

Figure 3: Toxic element levels.BD = birth defect

Overall, 80% of the controls were mothers who lived in an urban location, while 61% of the birth defect group lived in rural areas (Table 4). This finding was expected as most patients were referrals for tertiary care.

Fetal BD | Urban, n (%) | Rural, n (%) | P-value
Yes | 7 (38.9) | 11 (61.1) | 1.0
No | 4 (80) | 1 (20)

On secondary analysis, there was a significant difference in levels of copper and magnesium based on geographic location. Higher levels of copper were found in the maternal serum of mothers who lived in an urban location, while magnesium levels were found to be higher in mothers living in rural locations (Table 5).

Metal | Urban | Rural | P-value
Arsenic | 0.8 | 0.5 | 0.22
Barium | 1.31 | 3.15 | 0.42
Cadmium | 0.31 | 0.26 | 0.36
Calcium | 6.46 | 6.78 | 0.28
Cobalt | 0.35 | 0.39 | 0.36
Copper | 163.5 | 138.3 | 0.03
Lead | 0.45 | 0.33 | 0.10
Lithium | 0.58 | 1.21 | 0.28
Magnesium | 2.72 | 3.66 | <0.01
Manganese | 15.4 | 14.5 | 0.80
Mercury | 0.66 | 0.36 | 0.16
Molybdenum | 0.9 | 0.71 | 0.42
Nickel | 1.5 | 1.66 | 0.44
Platinum | 0.05 | 0.05 | 1.0
Selenium | 163.7 | 166.5 | 0.71
Strontium | 19.3 | 22.38 | 0.84
Thallium | 0.05 | 0.02 | 1.0
Uranium | 0.02 | 0.02 | 1.0
Zinc | 497.4 | 563.6 | 0.21