The role of maternal smoking as a causal factor for the incidence of childhood asthma is still not clearly established. It was investigated among 3- and 4-year-old-child incident cases confirmed by a 6-year follow-up (n = 294) and cases who no longer had symptoms after diagnosis (n = 110). The study took place in Montreal, Canada, between 1988 and 1997. Persistent and transient cases were compared with their respective controls from the original case-control study of incidence. The odds ratio for heavy maternal smoking adjusted for known risk factors for asthma was 3.84 (95% confidence interval: 1.68, 8.76) among persistent cases and close to one among transient cases. (+info)
Association of childhood cancer with factors related to pregnancy and birth.
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BACKGROUND: It has been hypothesized that risk factors of childhood cancers may already operate during the prenatal and neonatal period. Results of previous epidemiological studies have been inconsistent. METHODS: During 1992-1997 a large case-control study on childhood cancers and a variety of potential risk factors was conducted in Germany. Cases were ascertained by the German Childhood Cancer Registry. Each case was matched to a population-based control of the same age and gender, sampled from the district where the case lived at the date of diagnosis. For the analyses, 2358 cases and 2588 controls were available. RESULTS: Risk of childhood acute leukaemia increased with maternal age < or =20 years at time of delivery (odds ratio [OR] = 1.9, 95% CI: 1.1-3.2), lower (<2500 g: OR = 1.7, 95% CI: 1.1-2.8) and higher birthweight (>4000 g: OR = 1.4, 95% CI: 1.0-1.8, P < 0.05), and hormonal treatment because of infertility (OR = 1.6, 95% CI: 1.0-2.5, P < 0.05). No associations were seen for parental smoking habits, maternal alcohol consumption during pregnancy and fetal losses. Parity was associated only with subgroups of acute leukaemias. Regarding non-Hodgkin's lymphoma we observed an elevated OR for lower birthweight and heavy maternal smoking during pregnancy (>20 cigarettes/day) and a decreased OR for children with one or two siblings. Only a few significant findings were seen for the different groups of solid tumours. CONCLUSIONS: Overall, only weak associations were identified and the evaluated risk factors operating during the neonatal and prenatal period account at most for only a small proportion of childhood cancers. (+info)
Increased blood pressure in adolescents who were small for gestational age at birth: a cohort study in Brazil.
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BACKGROUND: This paper studies the relationship between birthweight for gestational age and blood pressure in adolescents aged 14-15 years in southern Brazil. METHODS: A sample of 1076 adolescents belonging to a cohort of over 6000 children born in 1982 in Pelotas, southern Brazil, was studied in 1997. All households in a sample of 25% of the city's census tracts were visited and all adolescents born in 1982 were interviewed, weighed, and their blood pressures were measured twice. Data from the adolescents were linked to the database through their names and dates of births. RESULTS: High diastolic and systolic pressure (defined as >95th percentile) were significantly more frequent among adolescents who were born below the 10th percentile of birthweight for gestational age. No association was found between high blood pressure and low birthweight or preterm births. In a multiple linear regression analysis, the association between birthweight for gestational age and blood pressure was not statistically significant after adjusting for age, sex, skin colour and family income. However, when the current body mass index and height were added to the model both diastolic and systolic pressure were significantly associated with birthweight for gestational age, and adolescents who were small for gestational age at birth presented a mean elevation of 3.08 mmHg for diastolic pressure and 2.89 mmHg for systolic pressure. CONCLUSIONS: There is an inverse association between birthweight for gestational age and blood pressure during adolescence. This association, however, is only disclosed when the negative confounding effect of the body mass index is controlled for. The same association is not found when the effects of birthweight and gestational age on blood pressure are analysed separately. It appears therefore that the elevation of blood pressure during adolescence only occurs when there was intra-uterine growth retardation. (+info)
Maternal infections in pregnancy and the development of asthma among offspring.
(12/1469)
BACKGROUND: Previous studies have suggested that asthma phenotype could probably be programmed before birth. The current study examined the impact of maternal vaginitis and febrile infections during pregnancy on the subsequent development of asthma among children. METHODS: The analyses were based on 8088 children from the northern Finland birth cohort, 1985-1986. RESULTS: The prevalence of asthma at age 7 was 3.5%. Children had a higher risk of asthma if their mothers experienced vaginitis and febrile infections during pregnancy, odds ratio (OR) = 1.41, (95% CI: 1.08-1.84) and 1.65 (95% CI: 1.25-2.18), respectively, after adjusting for other covariates. There was a clear time trend in risk of childhood asthma corresponding to the timing of maternal febrile infections in pregnancy. The adjusted OR for the first, second and third trimesters were 2.08 (95% CI: 1.13-3.82), 1.73 (95% CI: 1.09-2.75) and 1.44 (95% CI: 0.97-2.15), respectively. Maternal history of allergic diseases, birthweight <2500 g and male gender also seemed to be risk factors for childhood asthma. CONCLUSIONS: Our results suggest that further investigation of the relation of maternal infections during pregnancy to asthma among children seems warranted. (+info)
Respiratory tract inflammation during the induction of chronic bronchitis in rats: role of C-fibres.
(13/1469)
The hypothesis that chronic stimulation of C-fibres by inhaled irritants contributes to the inflammatory changes that occur during the development of chronic bronchitis was tested. The effect of neonatal capsaicin pretreatment on the development of respiratory tract inflammation was examined in a rat model of chronic bronchitis induced by SO2 exposure. Adult capsaicin- and vehicle-treated rats were exposed to SO2 (250 parts per million (ppm) 5 h x day(-1)) for one day, 2 weeks or 4 weeks. Nasal (NL), airway (AL) and bronchoalveolar (BAL) lavages were performed and the number and types of cells in the lavage fluids measured. SO2-induced changes in ventilation were also measured on day 1 of SO2 exposure and in the 3rd and 5th week of exposure. In the vehicle-treated rats, neutrophils became elevated in NL after just one day of SO2 exposure, in AL after 2 weeks, and in the BAL after 4 weeks. In comparison to vehicle animals, more neutrophils were recovered in the AL of capsaicin-treated rats after one day of SO2 (p=0.012), and in the BAL after 2 or 4 weeks (p=0.004 and p=0.01, respectively). On day 1, SO2 caused a transient increase in tidal volume and a sustained decrease in frequency that was not different in capsaicin- and vehicle-treated rats. With continued exposure, these ventilatory responses to SO2 were attenuated in both groups of rats. These data support the hypothesis that the presence of C-fibres limits or delays the inflammation that occurs during the development of chronic bronchitis induced by SO2 exposure. The protective effect of C-fibres is not the result of ventilatory responses to stimulation of these afferents. (+info)
Environmental tobacco smoke exposure and small-for-gestational-age birth.
(14/1469)
The aim of this analysis was to examine the effect of environmental tobacco smoke exposure on the risk of small-for-gestational-age (SGA) birth. The study population included 2,283 nonsmokers from a nested cohort study undertaken in southern Connecticut from 1988 to 1992. The duration and intensity of exposures incurred at multiple locations during the third trimester of pregnancy were measured by postpartum interview. The effect of exposure on birth weight and on incidence of SGA birth was assessed by multivariate logistic and linear regression. An estimated 26.5% of the women had been exposed to environmental tobacco smoke for at least 1 hour per week during the third trimester. The median duration of exposure among the exposed over all locations was 5 hours per week. The adjusted odds ratio for SGA birth in exposed mothers compared with unexposed mothers, using a dichotomous exposure variable, was 0.82 (95% confidence interval: 0.51, 1.33). The adjusted birth weight difference associated with exposure was -1.2 g (95% confidence interval: -43.3, 41.0). No effect of environmental tobacco smoke exposure on fetal growth was seen in this relatively homogeneous upper middle class group of women exposed at low levels. This is reassuring for women exposed at low levels, but it does not exclude the possibility of an effect in women exposed to higher levels of environmental tobacco smoke. (+info)
Anophthalmia in litters of female rats treated with the food-derived carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine.
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Anophthalmia in litters of pregnant rats treated with 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a food-derived carcinogen, was incidentally encountered in a risk-assessment study with 2-generation exposure to PhIP. Female Fischer 344 animals were given 200 ppm PhIP in the diet for 4 wk before mating with nontreated males and also during gestation and lactation periods. Mean numbers of newborn rats per litter in control and PhIP-treated groups were 7.9 +/- 2.9 and 7.1 +/- 1.6 in trial 1 and 8.3 +/- 1.9 and 6.1 +/- 2.4 in trial 2. Among 49 (trial 1) and 63 (trial 2) offspring from PhIP-treated dams, 9 (18.4%) and 32 (50.8%) demonstrated anophthalmia, and 1 (2.0%) and 8 (12.7%) demonstrated hydrocephaly. Five of 7 (71.4%) and 13 of 14 (92.9%) dams delivered pups with malformations in trials 1 and 2, respectively. Also, in a previous study that was carried out with the same protocol and that used the Sprague-Dawley strain of rats, anophthalmia and hydrocephaly were observed in 2 and 1 out of 175 pups, respectively, from 100 ppm PhIP-treated dams. No congenital malformations were found in control groups of the same size in either experiment. In addition to having been previously identified as a cause of carcinogenic activity, our findings suggest that PhIP is capable of causing anophthalmia in rats when administered during the gestational period. (+info)
Outdoor air pollution, low birth weight, and prematurity.
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This study tested the hypothesis, suggested by several recent reports, that air pollution may increase the risk of adverse birth outcomes. This study analyzed all singleton live births registered by the Czech national birth register in 1991 in 67 districts where at least one pollutant was monitored in 1990-1991 (n = 108,173). Maternal exposures to sulfur dioxide (SO(2)), total suspended particles (TSP), and nitrous oxides (NO(x)) in each trimester of pregnancy were estimated as the arithmetic means of all daily measurements taken by all monitors in the district of birth of each infant. Odds ratios of low birth weight (< 2,500 g), prematurity (< 37 weeks of gestation), and intrauterine growth retardation (IUGR; < 10th percentile of birth weight for gestational age and sex) were estimated by robust logistic regression. The median (and 25th and 75th percentile) trimester exposures were 32 (18, 56) microg/m(3) for SO(2); 72 (55, 87) microg/m(3) for TSP; and 38 (23, 59) microg/m(3) for NO(x). Low birth weight (prevalence 5.2%) and prematurity (prevalence 4.8%) were associated with SO(2) and somewhat less strongly with TSP. IUGR was not associated with any pollutant. The effects on low birth weight and prematurity were marginally stronger for exposures in the first trimester, and were not attenuated at all by adjustment for socioeconomic factors or the month of birth. Adjusted odds ratios of low birth weight were 1.20 [95% confidence interval (CI), 1.11-1.30] and 1.15 (CI, 1.07-1.24) for a 50 microg/m(3) increase in SO(2) and TSP, respectively, in the first trimester; adjusted odds ratios of prematurity were 1.27 (CI, 1.16-1.39) and 1.18 (CI, 1.05-1.31) for a 50 microg/m(3) increase in SO(2) and TSP, respectively, in the first trimester. Low gestational age accounted for the association between SO(2) and low birth weight. These findings provide further support for the hypothesis that air pollution can affect the outcome of pregnancy. (+info)