Dataset Information

Pregnancy Loss and Iodine Status: The LIFE Prospective Cohort Study.

ABSTRACT: Iodine deficiency in pregnancy is a common problem in the United States and parts of Europe, but whether iodine deficiency is associated with increased pregnancy loss has not been well studied. The LIFE study provided an excellent opportunity to examine the relationship between iodine status and pregnancy loss because women were monitored prospectively to ensure excellent ascertainment of conceptions. The LIFE study, a population-based prospective cohort study, monitored 501 women who had discontinued contraception within two months to become pregnant; 329 became pregnant, had urinary iodine concentrations measured on samples collected at enrollment, and were followed up to determine pregnancy outcomes. Of the 329, 196 had live births (59.5%), 92 (28.0%) had losses, and 41 (12.5%) withdrew or were lost to follow up. Urinary iodine concentrations were in the deficiency range in 59.6% of the participants. The risk of loss, however, was not elevated in the mildly deficient group (hazard ratio 0.69, 95% confidence interval 0.34, 1.38), the moderately deficient group (hazard ratio 0.81, 95% confidence interval 0.43, 1.51), or the severely deficient group (hazard ratio 0.69, 95% confidence interval 0.32, 1.50). Iodine deficiency, even when moderate to severe, was not associated with increased rates of pregnancy loss. This study provides some reassurance that iodine deficiency at levels seen in many developed countries does not increase the risk of pregnancy loss.

SUBMITTER: Mills JL

PROVIDER: S-EPMC6471412 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Pregnancy Loss and Iodine Status: The LIFE Prospective Cohort Study.

Mills James L JL Ali Mehnaz M Buck Louis Germaine M GM Kannan Kurunthachalam K Weck Jennifer J Wan Yanjian Y Maisog Joe J Giannakou Andreas A Sundaram Rajeshwari R

Nutrients 20190301 3

Iodine deficiency in pregnancy is a common problem in the United States and parts of Europe, but whether iodine deficiency is associated with increased pregnancy loss has not been well studied. The LIFE study provided an excellent opportunity to examine the relationship between iodine status and pregnancy loss because women were monitored prospectively to ensure excellent ascertainment of conceptions. The LIFE study, a population-based prospective cohort study, monitored 501 women who had discon ...[more]

PMID: 30823683

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Project description:PurposePregnant women in Sweden are mildly iodine deficient. We investigated the effect of daily iodine supplementation on the iodine and thyroid status of pregnant women.MethodsIn this pilot, randomized, double-blind trial, 200 thyroid-healthy pregnant women were recruited at mean (standard deviation) pregnancy week 8.85 (1.62) and assigned (1:1) to daily intake of a multivitamin tablet with or without 150 μg of iodine. Urine and serum samples were collected at baseline and once during the second and third trimesters. Urinary iodine concentration (UIC), serum thyroglobulin (Tg), thyroid-stimulating hormone (TSH), free thyroxine (FT4), and thyroid peroxidase antibodies (TPOabs) were analyzed. Neonatal TSH data were collected. UIC and Tg were also analyzed in a group of 89 thyroid-healthy non-pregnant women of reproductive age (WRA).ResultsAt baseline, the intervention and the control groups had similar median UIC (interquartile range (IQR)): 110 μg/L (74-119) and 111 μg/L (66-168), respectively. The intervention group reached iodine sufficiency with median UIC (IQR) 139 μg/L (89-234) and 136 μg/L (91-211) in the second and third trimester, respectively, without significant difference from the lower limit of the recommended range, i.e. 150-250 μg/L (p = 0.42 and p = 0.87, respectively). The intervention group had higher median UIC and lower median Tg compared to the control group during the second (p < 0.001 and p = 0.019, respectively) and third trimester (p < 0.001 and p = 0.003, respectively), whereas thyroid hormones, serum TPOabs, and neonatal TSH were similar. The WRA group presented median UIC (IQR) 65 μg/L (30-98) and median Tg (IQR) 18 μg/L (13-27).ConclusionA daily supplement containing 150 μg of iodine to a group of pregnant women with mild iodine deficiency improved the iodine status from mild ID to iodine sufficiency. This improvement seems to have had a positive impact on maternal thyroglobulin. This study is now under extension to investigate the children's neuropsychological development.Trial registrationClinicalTrials.gov Identifier NCT02378246, May 3, 2015, retrospectively registered.

Project description:BACKGROUND:Vitamin D deficiency during pregnancy is associated with adverse pregnancy outcomes, although the association between preconception vitamin D concentrations and livebirth is unknown. We aimed to assess the association between preconception vitamin D and pregnancy outcomes among women with proven fecundity. METHODS:We did a secondary analysis of a prospective cohort from the block-randomised, double-blind, placebo-controlled EAGeR trial. Women aged 18-40 years with one to two previous pregnancy losses were recruited from June 15, 2007, to July 15, 2011, at four clinical sites in the USA and followed up for up to six menstrual cycles while attempting pregnancy and throughout pregnancy if they conceived. Serum 25-hydroxyvitamin D was measured at baseline (preconception) and 8 weeks of gestation. Outcomes of interest included clinical pregnancy, time to pregnancy, pregnancy loss, and livebirths. Risk ratios (RRs) and 95% CIs for livebirths, pregnancy, and pregnancy loss were estimated with weighted log-binomial regression. To assess time to pregnancy, we used discrete time Cox proportional hazards models to calculate fecundability odds ratios (FORs) with 95% CIs. EAGeR is registered with ClinicalTrials.gov, number NCT00467363. FINDINGS:1191 women had available data on preconception 25-hydroxyvitamin D concentrations. 555 (47%) women were classified as having sufficient concentrations (?75 nmol/L) and 636 (53%) as having insufficient concentrations (<75 nmol/L). Women with sufficient preconception 25-hydroxyvitamin D were more likely to achieve clinical pregnancy (adjusted RR 1·10 [1·01-1·20]) and livebirth (1·15 [95% CI 1·02-1·29]) than were women with insufficient concentrations. Among women who achieved pregnancy, sufficient preconception 25-hydroxyvitamin D, but not that at 8 weeks of gestation, was associated with reduced risk of pregnancy loss (preconception RR per 25 nmol/L 0·88 [95% CI 0·77-0·99]; 8 weeks of gestation 0·98 [0·95-1·01]). No association was observed with fecundability in women with sufficient versus those with insufficient preconception 25-hydroxyvitamin D concentrations (adjusted FOR 1·13 [95% CI 0·95-1·34]). INTERPRETATION:Sufficient preconception 25-hydroxyvitamin D (?75 nmol/L) was associated with increased likelihood of pregnancy and livebirth. Increased vitamin D concentrations before conception, but not in early pregnancy, were associated with reduced pregnancy loss. FUNDING:National Institutes of Health and Doris Duke Charitable Foundation.

Dataset Information

Pregnancy Loss and Iodine Status: The LIFE Prospective Cohort Study.

Publications

Pregnancy Loss and Iodine Status: The LIFE Prospective Cohort Study.

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