Marisa Rebagliato

Maternal vitamin D status in pregnancy and risk of lower respiratory tract infections, wheezing, and asthma in offspring.

Background: Adequate vitamin D status in mothers during pregnancy may influence the health status of the child later in life. We assessed whether maternal circulating 25-hydroxyvitamin D (25[OH]D) concentrations in pregnancy are associated with risk of lower respiratory tract infections, wheezing, and asthma in the offspring. Methods: Data were obtained from 1724 children of the INfancia y Medio Ambiente (INMA) Project, a population-based birth cohort study. Maternal circulating 25(OH)D concentrations were measured in pregnancy (mean gestational age = 12.6 [SD = 2.5] weeks). When the child was age 1 year, parents were asked if their child had a physician-confirmed history of lower respiratory tract infections or a history of wheezing. The questions about wheezing were repeated annually thereafter. Asthma was defined as parental report of doctor diagnosis of asthma or receiving treatment at the age of 4–6 years or wheezing since the age of 4 years. Results: The median maternal circulating 25(OH)D concentration in pregnancy was 29.5 ng/mL (interquartile range, 22.5–37.1 ng/mL). After multivariable adjustment, there was a trend for an independent association between higher levels of maternal circulating 25(OH)D levels in pregnancy and decreased odds of lower respiratory tract infections in offspring (for cohort- and season-specific quartile Q4 vs. Q1, odds ratio = 0.67 [95% confidence interval = 0.50–0.90]; test for trend, P = 0.016). We found no association between 25(OH)D levels in pregnancy and risk of wheezing at age 1 year or 4 years, or asthma at age 4–6 years. Conclusions: Higher maternal circulating 25(OH)D concentrations in pregnancy were independently associated with lower risk of lower respiratory tract infections in offspring in the first year of life but not with wheezing or asthma in childhood.

Air pollution exposure during pregnancy and reduced birth size: a prospective birth cohort study in Valencia, Spain

BackgroundMaternal exposure to air pollution has been related to fetal growth in a number of recent scientific studies. The objective of this study was to assess the association between exposure to air pollution during pregnancy and anthropometric measures at birth in a cohort in Valencia, Spain.MethodsSeven hundred and eighty-five pregnant women and their singleton newborns participated in the study. Exposure to ambient nitrogen dioxide (NO2) was estimated by means of land use regression. NO2 spatial estimations were adjusted to correspond to relevant pregnancy periods (whole pregnancy and trimesters) for each woman. Outcome variables were birth weight, length, and head circumference (HC), along with being small for gestational age (SGA). The association between exposure to residential outdoor NO2 and outcomes was assessed controlling for potential confounders and examining the shape of the relationship using generalized additive models (GAM).ResultsFor continuous anthropometric measures, GAM indicated a change in slope at NO2 concentrations of around 40 μg/m3. NO2 exposure >40 μg/m3 during the first trimester was associated with a change in birth length of -0.27 cm (95% CI: -0.51 to -0.03) and with a change in birth weight of -40.3 grams (-96.3 to 15.6); the same exposure throughout the whole pregnancy was associated with a change in birth HC of -0.17 cm (-0.34 to -0.003). The shape of the relation was seen to be roughly linear for the risk of being SGA. A 10 μg/m3 increase in NO2 during the second trimester was associated with being SGA-weight, odds ratio (OR): 1.37 (1.01-1.85). For SGA-length the estimate for the same comparison was OR: 1.42 (0.89-2.25).ConclusionsPrenatal exposure to traffic-related air pollution may reduce fetal growth. Findings from this study provide further evidence of the need for developing strategies to reduce air pollution in order to prevent risks to fetal health and development.

Reproducibility and validity of a food frequency questionnaire among pregnant women in a Mediterranean area

BackgroundStudies exploring the role of diet during pregnancy are still scarce, in part due to the complexity of measuring diet and to the lack of valid instruments. The aim of this study was to examine the reproducibility and validity (against biochemical biomarkers) of a semi-quantitative food frequency questionnaire (FFQ) in pregnant women.MethodsParticipants were 740 pregnant women from a population-based birth cohort study in Valencia (INMA Study). We compared nutrient and food intakes from FFQs estimated for two periods of pregnancy (reproducibility), and compared energy-adjusted intake of several carotenoids, folate, vitamin B12, vitamin C and α-tocopherol of the FFQ in the first trimester with their concentration in blood specimens (validity).ResultsSignificant correlations for reproducibility were found for major food groups and nutrients but not for lycopene (r=0.06); the average correlation coefficients for daily intake were 0.51 for food groups and 0.61 for nutrients. For validity, statistically significant correlations were observed for vitamin C (0.18), α-carotene (0.32), β-carotene (0.22), lutein-zeaxantin (0.29) and β-cryptoxantin(0.26); non-significant correlations were observed for retinol, lycopene, α-tocopherol, vitamin B12 and folate (r≤0.12). When dietary supplement use was considered, correlations were substantially improved for folate (0.53) and to a lesser extent for vitamin B12 (0.12) and vitamin C (0.20).ConclusionThis study supports that the FFQ has a good reproducibility for nutrient and food intake, and can provide a valid estimate of several important nutrients during pregnancy.

Thyroxine levels during pregnancy in healthy women and early child neurodevelopment.

Background: The fetus depends on maternal thyroid hormones during pregnancy for normal brain development. Little is known about the effects of subclinical hypothyroidism and mild hypothyroxinemia during pregnancy on neurodevelopment of the child. Methods: We evaluated a population-based birth cohort in Spain. A total of 1761 children and their mothers were included in the main analyses. Serum levels of free thyroxine and thyrotropin were measured in pregnant women. Mental and psychomotor development of their children was assessed using the Bayley Scales of Infant Development during the second year of life. Results: Low free thyroxine levels (<5th percentile) and self-reported prepregnancy thyroid disorder without medical treatment were associated with a decrease of mental scores (Beta = −3.4 [95% confidence interval= −6.7 to −0.2]) and −5.5 [−8.9 to −2.0], respectively). No association between thyrotropin levels and mental scores or psychomotor scores was observed. Conclusions: Low free thyroxine levels in healthy pregnant women are related to a moderate delay in child neurodevelopment. The impairment is similar in magnitude to that observed in mothers with untreated prepregnancy thyroid disorder. The value of screening pregnant women for thyroid function requires further assessment, particularly in mildly iodine-deficient areas.

Fish consumption during pregnancy, prenatal mercury exposure, and anthropometric measures at birth in a prospective mother-infant cohort study in Spain

BACKGROUND Birth size has been shown to be related to maternal fish intake, although the results are inconsistent. OBJECTIVE The objective was to assess the association of consumption of different types of fish and prenatal mercury exposure with birth weight, birth length, and classification as small for gestational age (SGA) in newborns. DESIGN Cord blood total mercury was measured in 554 newborns in a population-based cohort born from 2004 to 2006. Fish consumption was classified in 4 frequency categories (<1 portion/mo, 1-3 portions/mo, 1 portion/wk, and > or =2 portions/wk). RESULTS When multivariate models were adjusted, newborns in the higher quartile of total mercury weighed 143.7 g less (95% CI: -251.8, -35.6; P for trend = 0.02) and had higher odds of being SGA for length (odds ratio: 5.3; 95% CI: 1.2, 23.9; P from likelihood ratio test = 0.03) without a linear relation (P for trend = 0.13) compared with those in the lowest quartile. Mothers consuming >/=2 portions/wk of canned tuna had newborns who weighed more than those who consumed <1 portion/mo (P for trend = 0.03) and a lower risk of having infants who were SGA for weight (P for trend = 0.01). Consumption of > or =2 portions/wk of large oily fish was associated with a higher risk of being SGA for weight and consumption of lean fish with a lower risk of being SGA for length compared with the consumption of <1 portion/mo, but in neither case was there a linear relation (P for trend >0.05). CONCLUSIONS The role of fish in fetal growth depends on the amount and type of fish consumed. The findings for mercury warrant further investigation in other settings.

Preterm birth and exposure to air pollutants during pregnancy

BACKGROUND Research has shown that prenatal exposure to air pollutants may have a detrimental effect on fetal development, with the strength of the relationship depending on the effect being studied. The evidence to date, however, is insufficient to establish a direct causal link between such exposure and preterm delivery. This study evaluates the specific effect of prenatal exposure to NO(2) and benzene on preterm births. METHODS The population under study comprised 785 pregnant women who formed part of the INMA cohort in Valencia, Spain (2003-2005). Multiple regression models were used for mapping outdoor nitrogen dioxide (NO(2)) and benzene levels throughout the area. Individual exposure was assigned as the estimated outdoor levels at each womans home measured during each trimester as well as throughout the entire pregnancy. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated in order to assess the association between preterm birth and exposure to NO(2) and benzene. The shape of the exposure-response curve between air pollution and the risk of preterm birth was analyzed with a flexible approach, introducing a natural cubic spline for air pollution levels into the model. RESULTS Pregnant women exposed to NO(2) and benzene have an increased risk of preterm birth. This risk was shown to be significant when women were exposed to NO(2) levels >46.2 μg/m(3) during the second and third trimesters as well as throughout the entire pregnancy and to benzene levels >2.7 μg/m(3) throughout the entire pregnancy. CONCLUSION These results suggest that maternal exposure to traffic-related air pollution is associated with preterm birth.

Effect of Iodine Supplementation During Pregnancy on Infant Neurodevelopment at 1 Year of Age

Iodine is the main constituent of thyroid hormones, which in turn are required for fetal brain development. However, the relation between iodine intake during pregnancy, thyroid function, and child neurodevelopment needs further evaluation. The authors assessed the association of maternal iodine intake from diet and supplements during pregnancy and of maternal and neonatal thyroid function with infant neurodevelopment. The Mental Development Index and Psychomotor Development Index (PDI) for 691 children were obtained between 2005 and 2007 using the Bayley Scales of Infant Development at age 1 year in a prebirth cohort in Valencia, Spain. In multivariate analyses, a maternal thyrotropin level >4 μU/mL was associated with an increased risk of a PDI <85 (odds ratio = 3.5, P = 0.02). Maternal intake of ≥150 μg/day, compared with <100 μg/day, of iodine from supplements was associated with a 5.2-point decrease in PDI (95% confidence interval: -8.1, -2.2) and a 1.8-fold increase in the odds of a PDI <85 (95% confidence interval: 1.0, 3.3). When analyses were stratified by sex, this association was intensified for girls but was not observed for boys. Further evidence on the safety and effectiveness of iodine supplementation during pregnancy is needed before it is systematically recommended in iodine-sufficient or mildly deficient areas.

Iodine Intake and Maternal Thyroid Function During Pregnancy

Background: An adequate iodine intake during pregnancy is essential for the synthesis of maternal thyroid hormones and normal brain development in the fetus. Scant evidence is available on the effects and safety of iodine supplementation during pregnancy in areas with adequate or mildly deficient iodine intake. We examined the association of maternal iodine intake and supplementation with thyroid function before 24 weeks of gestation in population-based samples from 3 different areas in Spain. Methods: A cross-sectional study of 1844 pregnant women (gestational age range 8–23 weeks) was carried out in 3 areas in Spain (Guipúzcoa, Sabadell, Valencia), during the period 2004–2008. We measured levels of free thyroxine and thyroid-stimulating hormone (TSH) in serum, iodine in a spot urine sample, and questionnaire estimates of iodine intake from diet, iodized salt and supplements. Adjusted associations were assessed by multiple linear regression and logistic regression analyses. Results: There was an increased risk of TSH above 3 &mgr;U/mL in women who consumed 200 &mgr;g or more of iodine supplements daily compared with those who consumed less than 100 &mgr;g/day (adjusted odds ratio = 2.5 [95% confidence interval = 1.2 to 5.4]). We observed no association between urinary iodine and TSH levels. Pregnant women from the area with the highest median urinary iodine (168 &mgr;g/L) and highest supplement coverage (93%) showed the lowest values of serum free thyroxine. (geometric mean = 10.09 pmol/L [9.98 to 10.19]). Conclusions: Iodine supplement intake in the first half of pregnancy may lead to maternal thyroid dysfunction in iodine-sufficient or mildly iodine-deficient populations.

Prenatal Exposure to Mercury and Infant Neurodevelopment in a Multicenter Cohort in Spain: Study of Potential Modifiers

Vulnerability of the central nervous system to mercury is increased during early development. This study aimed to evaluate whether cord blood total mercury levels may have a negative effect on both mental and psychomotor development in a maternal-birth cohort from moderate-high fish consumption areas. Study subjects were 1,683 child participants in the INMA (Environment and Childhood) Project from 4 areas of Spain between 2003 and 2010. Cord blood total mercury levels were analyzed by atomic absorption spectrometry. Infant neurodevelopment was assessed around age 14 months by the Bayley Scales of Infant Development. Sociodemographic, lifestyle, and dietary information was obtained by questionnaire during pregnancy. The geometric mean of total mercury levels was 8.4 μg/L (95% confidence interval (CI): 8.1, 8.7). In multivariate analysis, a doubling in total mercury levels did not show an association with mental (β = 0.1, 95% CI: -0.68, 0.88) or psychomotor (β = -0.05, 95% CI: -0.79, 0.68) developmental delay; however, stratified findings by sex suggest a negative association between prenatal exposure to total mercury and psychomotor development among female infants (β = -1.09, 95% CI: -2.21, 0.03), although follow-up is required to confirm these results.

Diet quality in early pregnancy and its effects on fetal growth outcomes: the Infancia y Medio Ambiente (Childhood and Environment) Mother and Child Cohort Study in Spain

BACKGROUND Maternal diet has been associated with fetal growth outcomes; however, evidence is scarce on the role of dietary quality. OBJECTIVE The objective was to assess the effect of diet quality during the first trimester of pregnancy, as measured by the Alternate Healthy Eating Index (AHEI) adapted for pregnancy, on fetal growth. DESIGN We studied 787 women and their newborns from a Spanish cohort study. Diet quality was assessed by using a modification of the AHEI. Adjusted birth weight, birth length, and head circumference were used as continuous outcomes. We used a customized model to define fetal growth restriction in weight, length, and head circumference. RESULTS After adjustment of multivariate models, a positive association was observed between diet quality and adjusted birth weight and adjusted birth length. The greatest differences were found between the fourth and first quintiles of the AHEI. Newborns of women in the fourth quintile were on average 126.3 g (95% CI: 38.5, 213.9 g) heavier and 0.47 cm (95% CI: 0.08, 0.86 cm) longer than those in the lowest quintile (P for trend = 0.009 and 0.013, respectively). Women with the highest AHEI scores had a significantly lower risk of delivering a fetal growth-restricted infant for weight (odds ratio: 0.24; 95% CI: 0.10, 0.55; P for trend = 0.001) than did women in the lowest quintile, but this was not the case for fetal growth restriction in length (P for trend = 0.538) or head circumference (P for trend = 0.070). CONCLUSION A high-quality diet in the first trimester of pregnancy is associated with birth size and the risk of fetal growth restriction.