This nested case-control study measured molybdenum in plasma from pregnant women in a Beijing birth cohort in the first and third trimesters. Plasma molybdenum rose between trimesters, and women in the highest first-trimester quartile had about twice the odds of spontaneous preterm birth after adjustment. The authors call the finding preliminary and note that reference ranges for blood molybdenum in pregnancy are not defined in China.
Key numbers
All plasma values are ng/mL, median (IQR) (Table 2, p. 264).
- First trimester (7 to 9 weeks): all women 2.07 (1.53 to 2.58); cases 2.12 (1.56 to 2.69) vs controls 2.02 (1.46 to 2.50), P = 0.027.
- Third trimester (33 to 34 weeks): all women 2.59 (1.66 to 3.55); cases 2.66 (1.69 to 3.69) vs controls 2.54 (1.58 to 3.41), P = 0.147. Third-trimester levels were higher than first-trimester levels (P < 0.001).
- First trimester, highest quartile (2.584 ng/mL or more) vs lowest: adjusted OR 2.074 (95% CI 1.212 to 3.550), P = 0.008, P for trend 0.017 (Table 3, p. 264).
- Third trimester, highest quartile (3.554 ng/mL or more) vs lowest: adjusted OR 1.732 (95% CI 1.016 to 2.953), P = 0.044 (Table 3, p. 264).
- Limit of detection 0.04 ng/mL; all samples were above it (p. 262).
- Comparison values quoted from other cohorts: maternal plasma 1.9 µg/L at 10 to 13 weeks (n = 1,720) and serum 2.378 to 2.816 ng/mL in other Chinese studies (p. 264 to 265; secondary).
Methods (brief)
From 29,303 live singleton births, 236 spontaneous preterm births with blood samples from both trimesters were matched with 236 term controls. Fasting venous plasma was analyzed by ICP-MS (ELAN DRC II) with commercial plasma controls. Unconditional logistic regression adjusted for maternal age, ethnicity, pre-pregnancy body mass index, parity, delivery mode, education and income.
Evidence fitness
Provides measured plasma molybdenum levels in pregnant women and an observational association with preterm birth. It does not establish causation or identify dietary sources, and the authors did not record supplement or medication use.
Limitations
Single city and hospital. Associations are modest and partly driven by subgroups (overweight, obese or multiparous women). Molybdenum sources (diet, water, supplements) were not assessed. Statements on food sources and health effects in the discussion are secondary.
Related evidence
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