Time to pregnancy among women occupationally exposed to lead.

A retrospective time-to-pregnancy study was conducted among women biologically monitored for exposure to lead. The women were participants of a previous study on spontaneous abortion. They were classified into exposure categories on the basis of questionnaire information, and individual blood lead (B-Pb) measurements. The adjusted incidence density ratios (IDR) of clinically recognized pregnancies were .93 (95% confidence interval [CI] .56 to 1.57) for very low (B-Pb < .5 mumol/L), .84 (CI .48 to 1.45) for low (B-Pb .5 to .9 mumol/L), and .80 (CI 0.42 to 1.54) for higher (B-Pb > or = 1.0 mumol/L) exposure compared with no exposure, in the discrete proportional hazards analysis. Exposure to inorganic lead was not associated with fecundability at current, low-exposure levels. The suggestive finding among the eight most heavily exposed women (B-Pb 1.4 to 2.4 mumol/L, IDR .53; CI .19 to 1.52) should be confirmed or refuted in a larger study.