Thyroid antagonists and thyroid indicators in U.S. pregnant women in the Vanguard Study of the National Children's Study.

The sodium iodide-symporter (NIS) mediates uptake of iodide into thyroid follicular cells. This key step in thyroid hormone synthesis is inhibited by perchlorate, thiocyanate (SCN) and nitrate (NO3) anions. When these exposures occur during pregnancy the resulting decreases in thyroid hormones may adversely affect neurodevelopment of the human fetus. Our objectives were to describe and examine the relationship of these anions to the serum thyroid indicators, thyroid stimulating hormone (TSH) and free thyroxine (FT4), in third trimester women from the initial Vanguard Study of the National Children's Study (NCS); and to compare urine perchlorate results with those in pregnant women from the National Health and Nutritional Examination Survey (NHANES). Urinary perchlorate, SCN, NO3, and iodine, serum TSH, FT4, and cotinine were measured and a food frequency questionnaire (FFQ) was administered to pregnant women enrolled in the initial Vanguard Study. We used multiple regression models of FT4 and TSH that included perchlorate equivalent concentration (PEC, which estimates combined inhibitory effects of the anions perchlorate, SCN, and NO3 on the NIS). We used multiple regression to model predictors of each urinary anion, using FFQ results, drinking water source, season of year, smoking status, and demographic characteristics. Descriptive statistics were calculated for pregnant women in NHANES 2001-2012. The geometric mean (GM) for urinary perchlorate was 4.04µg/L, for TSH 1.46mIU/L, and the arithmetic mean for FT4 1.11ng/dL in 359 NCS women. In 330 women with completed FFQs, consumption of leafy greens, winter season, and Hispanic ethnicity were significant predictors of higher urinary perchlorate, which differed significantly by study site and primary drinking water source, and bottled water was associated with higher urinary perchlorate compared to filtered tap water. Leafy greens consumption was associated with higher urinary NO3 and higher urinary SCN. There was no association between urinary perchlorate or PEC and TSH or FT4, even for women with urinary iodine <100µg/L. GM urinary perchlorate concentrations in the full sample (n=494) of third trimester NCS women (4.03µg/L) were similar to pregnant women in NHANES (3.58µg/L).

Success rates for consent and collection of prenatal biological specimens in an epidemiologic survey of child health.

BACKGROUND: The National Children's Study (NCS) Vanguard Study began enrollment in January 2009 as an initial pilot study for a planned large-scale, longitudinal U.S. cohort study of the effect of environmental influences on child health and development, with biological and environmental sample collection conducted in seven locations from April 2009 to October 2010. We sought to determine rates of consent for, and success of collection of, maternal and paternal biospecimens before and during pregnancy in the NCS Vanguard Study. METHODS: Samples of blood, saliva, vaginal swabs, urine, hair, and nails were collected before and during pregnancy. All specimens were sent to a central repository for processing, storage, and quality assessment. RESULTS: Of 780 pregnant women asked to consent to sample collection, 773 (>99%) agreed, and of 295 nonpregnant women, 292 (99%) agreed. Of 440 fathers asked to consent to sample collection, 435 (99%) agreed. Frequency of successful collection of biospecimens varied depending on sample and visit type. In descending order, the ranges over all visit types of the proportion of expected samples successfully collected from women were: urine, 92.5 to 95.7%; hair, 89.6 to 92.5%; vaginal swab, 84.2 to 88.5%; blood, 74.9 to 78.5%; 2-day saliva, 65.8 to 81.6%; and nails, 76.4 to 76.7%. For fathers, rates were highest for urine (94.9%) and lowest for hair (63.0%). CONCLUSION: High rates of consent for and collection of a wide variety of biospecimens can be achieved in prospective epidemiologic cohort studies of pregnant women. Ease of sample collection may be a primary factor influencing successful biospecimen collection.