Early pregnancy blood lead and spontaneous abortion.

Although evidence tends to suggest that high levels of lead exposure increase the risk of spontaneous abortion, we do not yet know whether moderate- to low-level exposure elevates risk. Among 351 women (aged 16 to 35 years, with single pregnancies) who were registered for a longitudinal study, 15 (4.3%) women experienced spontaneous abortion after the 12th week of gestation and before the 20th week. We collected participants' blood samples during the first trimester of pregnancy (8-12 weeks) for lead measurement by inductively coupled plasma-mass spectrometry. Mean ± standard deviation of blood lead was 3.8 ± 2.0 µg/dl (range 1.0-20.5 µg/dl) with a geometric mean of 3.5 µg/dl. Mean blood lead concentrations did not differ significantly between spontaneous abortion cases and ongoing pregnancies (3.51 ± 1.42 and 3.83 ± 1.99 µg/dl, respectively). The findings suggest that in apparently healthy women, low blood lead levels (mean < 5 µg/dl) measured in early pregnancy may not be a risk factor for spontaneous abortion.

Early pregnancy blood lead levels and the risk of premature rupture of the membranes.

To clarify the effects of lead on fetal premature rupture of the membranes (PROM), blood lead concentrations were measured using inductively coupled plasma-mass spectrometry in 332 women, aged 16-35 years, during their early pregnancy period (8-12 weeks). Blood lead concentrations were significantly higher in the 36 PROM deliveries than in the 296 non-PROM deliveries (mean ± SD, 4.61 ± 2.37 and 3.69 ± 1.85 µg/dl, respectively; p<0.05). The logistic regression analysis revealed that a 1-unit increase in the logarithm of the blood lead level led to a several-fold increase in the risk of PROM (unit risk=17.98, 95% CI 1.6-198.6). Thus, it is suggested that lead can increase the risk of PROM in pregnant women with mean blood lead less than 5 µg/dl.