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J Fernández Alba

Publications and source records attributed to J Fernández Alba.

13 recordsLinked to original sources
PubMed1994

Changes in serial blood lead levels during pregnancy.

The first step in modeling lead kinetics during pregnancy includes a description of sequential maternal blood lead (PbB) during pregnancy and the factors controlling it. We analyzed PbB of 105 women living in the Valley of Mexico from week 12 to week 36 of pregnancy and again at parturition. We also used data from all women contributing blood at any stage of pregnancy to determine antecedents of PbB. Pregnancies were uneventful, and offspring were normal. Although geometric mean PbB level averaged around 7.0 micrograms/dl (0.34 mumol/l), with a range of 1.0-35.5 micrograms/dl throughout pregnancy, analysis of variance revealed a significant decrease in mean PbB from week 12 to week 20 (1.1 micrograms/dl) and various significant increases in mean PbB from week 20 to parturition (1.6 micrograms/dl). Regression analyses confirmed the positive linear PbB trend from 20 weeks to parturition and additional contributions of dietary calcium, reproductive history, lifetime residence of Mexico City, coffee drinking, and use of indigenous lead-glazed pottery. Although decreasing hematocrit has been suggested to explain first-half pregnancy PbB decrease, the time course of hematocrit decrease in the present study did not match the sequential changes in PbB. While hemodilution and organ growth in the first half of pregnancy may account for much of the PbB decrease seen between 12 and 20 weeks, the remaining hemodilution and accelerated organ growth of the last half of pregnancy do not predict the trend toward increasing maternal PbB concentration from 20 weeks to delivery. Mobilization of bone lead, increased gut absorption, and increased retention of lead may explain part of the upward PbB trend in the second half of pregnancy. Reduction of lifetime lead exposure may be required to decrease risk of fetal exposure.

Adult↗
PubMedDate not supplied

Maternal influences on cord blood lead levels.

We constructed models of umbilical cord blood lead (PbB), with and without the addition of maternal PbB at delivery and earlier in pregnancy, to determine which factors explaining cord PbB depended upon maternal PbB and which did not. We prospectively studied women of low-to-middle socioeconomic status who lived in the Valley of Mexico from 12 weeks of pregnancy to delivery. We measured maternal venous PbB during pregnancy and at delivery, and umbilical cord PbB (1-38 micrograms/dl, 0.05-1.83 mumol/l). We used multiple regression analyses to model cord PbB and a logit analysis to model the maternal-cord PbB relationship. Older mothers using lead-glazed pottery and canned foods delivered babies with increased cord PbB, while those with occasional alcohol use during pregnancy, high milk intake, and more spontaneous abortions delivered babies with lower cord PbB. Maternal PbB at 36 weeks of pregnancy and at delivery independently explained additional variance in cord PbB, but maternal PbB earlier in pregnancy did not. Some of the effects of lead-glazed pottery, maternal abortions, alcohol use, and canned food use on cord PbB were mediated through maternal PbB. The effects of maternal age and milk intake on cord PbB were independent of their influence on maternal PbB near delivery. Cord PbBs were higher than maternal PbBs at delivery in 33% of the cases, and were predominant in mothers over 30 and those drinking milk less than once per day. Measurable influence of maternal PbB on delivery cord PbB is limited to the four to eight weeks prior to delivery. Many factors suspected of influencing bone lead also control cord PbB, some of them independently of their effect on maternal delivery PbB. Minimizing fetal exposure near the end of pregnancy may require long-term control of maternal lead exposure and good management of pregnancy and diet.

Adolescent↗