Thyroid autoantibodies, specifically thyroid peroxidase antibodies, have been associated with miscarriage and pre-term birth in women with a normal thyroid function. Small randomised controlled trials have found that treatment with levothyroxine may reduce such adverse outcomes in pregnancy. The Thyroid AntiBodies and LEvoThyroxine (TABLET) trial was conducted to explore the effects of levothyroxine in euthyroid women with thyroid peroxidase antibodies. This was a randomised, double-blind, placebo-controlled, multicentre study conducted in 49 hospitals across the UK between 2011 and 2016. Euthyroid women who tested positive for thyroid peroxidase antibodies, were aged between 16 and 41 years and were trying to conceive either naturally or through assisted conception were eligible. Participants were randomised to levothyroxine at a dose of 50 mcg daily or placebo. The primary outcome was live birth at >= 34 completed weeks of gestation. Of the 19,556 women screened, 1420 were eligible and 952 were randomised. The live birth rate was 37% in the levothyroxine group and 38% in the placebo group (relative risk 0.97, 95% CI 0.83 to 1.14; p = 0.74). Levothyroxine therapy in a dose of 50 mcg per day does not improve live birth rate in euthyroid women with thyroid peroxidase antibodies.
PMID 31617987 31617987 DOI 10.3310/eme06110 10.3310/eme06110 Dhillon-Smith et al. 2019, Dhillon-Smith 2019
Cite this article
Dhillon-Smith, R. K., Middleton, L. J., Sunner, K. K., Cheed, V., Baker, K., Farrell-Carver, S., Bender-Atik, R., Agrawal, R., Bhatia, K., Edi-Osagie, E., Ghobara, T., Gupta, P., Jurkovic, D., Khalaf, Y., MacLean, M., McCabe, C., Mulbagal, K., Nunes, N., Overton, C., . . . Coomarasamy, A. (2019). Levothyroxine to increase live births in euthyroid women with thyroid antibodies trying to conceive: the TABLET RCT. Efficacy and Mechanism Evaluation, 6(11), 1-72. https://doi.org/10.3310/eme06110
Dhillon-Smith RK, Middleton LJ, Sunner KK, Cheed V, Baker K, Farrell-Carver S, et al. Levothyroxine to increase live births in euthyroid women with thyroid antibodies trying to conceive: the TABLET RCT. Efficacy Mech Eval. 2019;6(11):1-72. doi:10.3310/eme06110
Dhillon-Smith, R. K., et al. "Levothyroxine to increase live births in euthyroid women with thyroid antibodies trying to conceive: the TABLET RCT." Efficacy and Mechanism Evaluation, vol. 6, no. 11, 2019, pp. 1-72.
This narrative review examines the evidence for medical optimization of inflammatory conditions, vitamin deficiencies, endocrine disorders, immune dysregulation, oligo-ovulation, and luteal phase factors to improve fertility outcomes in women attempting to conceive through natural or timed intercourse. Overall, there is a paucity of data with respect to these categories among patients pursuing timed intercourse, precluding our ability to draw strong recommendations. However, there is strong evidence supporting treatment of endocrine disorders, specifically overt thyroid dysfunction and hyperprolactinemia, as well as oligo-ovulation. Conversely, treatment of subclinical hypothyroidism is not recommended. The current data are insufficient to support empiric use of antiinflammatory medications, corticosteroids, thyroid hormones, or vitamins or supplements to improve chances of pregnancy in a general infertility population.
Metabolic and Endocrine Agents · Thyroid Replacement
Akhtar MA et al., 2019·Cochrane Database Syst Rev·
Thyroid disease is the second most common endocrine disorder affecting women of reproductive age. Subclinical hypothyroidism is diagnosed by an elevated thyroid-stimulating hormone concentration with a normal concentration of free thyroxine hormone. Autoimmune thyroid disease (ATD) is diagnosed by the presence of thyroid autoantibodies, regardless of thyroid hormone levels. Thyroxine may be a useful treatment for subfertile women with these two specific types of thyroid disease for improving pregnancy outcomes during assisted reproduction. To evaluate the efficacy and harms of levothyroxine replacement in subfertile women with subclinical hypothyroidism or with normal thyroid function and thyroid autoimmunity (euthyroid autoimmune thyroid disease, or euthyroid ATD) undergoing assisted reproduction. We searched the Cochrane Gynaecology and Fertility (CGF) Group specialised register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL and two trials registers together with reference checking and contact with study authors and experts in the field to identify studies. We searched for all published and unpublished randomised controlled trials (RCTs) comparing thyroxine with no treatment or placebo, without language restrictions, from inception to 8 April 2019, and in consultation with the Cochrane CGF Information Specialist. We included women undergoing assisted reproduction treatment, meaning both in vitro fertilisation and intracytoplasmic sperm injection, with a history of subfertility and with subclinical hypothyroidism or with euthyroid ATD. We excluded women with a previously known clinical hypothyroidism or already taking thyroxine or tri-iodothyronine. RCTs compared thyroxine (levothyroxine) with either placebo or no treatment. We used standard methodological procedures expected by Cochrane. Our primary review outcomes were live birth and adverse events of thyroxine; our secondary outcomes were clinical pregnancy, multiple pregnancy and miscarriage. The review included four studies with 820 women. The included studies were of overall low risk of bias. Using GRADE methodology, we assessed the quality of evidence for the primary outcomes of this review to be very low- to low-quality evidence. Evidence was downgraded for imprecision as it was based on single, small trials with wide confidence intervals (CI). We were able to include data from three of the four included studies.In one study of women with both subclinical hypothyroidism and positive or negative anti-TPO antibodies (autoimmune disease), the evidence suggested that thyroxine replacement may have improved live birth rate (RR 2.13, 95% CI 1.07 to 4.21; 1 RCT, n = 64; low-quality evidence) and it may have led to similar miscarriage rates (RR 0.11, 95% CI 0.01 to 1.98; 1 RCT, n = 64; low-quality evidence). The evidence suggested that women with both subclinical hypothyroidism and positive or negative anti-TPO antibodies would have a 25% chance of a live birth with placebo or no treatment, and that the chance of a live birth in these women using thyroxine would be between 27% and 100%.In women with normal thyroid function and thyroid autoimmunity (euthyroid ATD), treatment with thyroxine replacement compared with placebo or no treatment may have led to similar live birth rates (risk ratio (RR) 1.04, 95% CI 0.83 to 1.29; 2 RCTs, number of participants (n) = 686; I(2) = 46%; low-quality evidence) and miscarriage rates (RR 0.83, 95% CI 0.47 to 1.46, 2 RCTs, n = 686, I(2) = 0%; low-quality evidence). The evidence suggested that women with normal thyroid function and thyroid autoimmunity would have a 31% chance of a live birth with placebo or no treatment, and that the chance of a live birth in these women using thyroxine would be between 26% and 40%.Adverse events were rarely reported. One RCT reported 0/32 in the thyroxine replacement group and 1/32 preterm births in the control group in women diagnosed with subclinical hypothyroidism and positive or negative anti-TPO antibodies. One RCT reported 21/300 preterm births in the thyroxine replacement group and 19/300 preterm births in the control group in women diagnosed with positive anti-TPO antibodies. None of the RCTs reported on other maternal pregnancy complications, foetal complications or adverse effects of thyroxine. AUTHORS' We could draw no clear conclusions in this systematic review due to the very low to low quality of the evidence reported.
Metabolic and Endocrine Agents · Thyroid Replacement
Thyroid disease in general, and hypothyroidism in particular, are very common in women. In the USA, the most common cause of primary thyroid deficiency is on an autoimmune basis due to lymphocytic (Hashimoto) thyroiditis. Because there are thyroid hormone receptors in virtually every tissue of the body, the manifestations of hypothyroidism are varied, but problems with abnormal menses, conception, fertility, and pregnancy can be especially troubling in young women. The single most important diagnostic test is measurement of serum thyrotropin (TSH). The overwhelming majority of patients with hypothyroidism are treated with a single daily dose of synthetic levothyroxine with the goal of therapy being restoration of a normal metabolic state with return of the TSH level down to the range of 0.5 to 1.5 mlU/L. "Subclinical" hypothyroidism refers to those patients with early or mild thyroid hypofunction manifested as slight elevations of thyrotropin (approximately 4-10 mlU/L) although serum thyroxine (T4) and triiodothyronine (T3) levels are within their reference ranges. The entity is somewhat controversial in regard to its consequences if left untreated, and whether or not we should be screening patients, at least susceptible populations, for the condition. Reports indicate an association between subclinical hypothyroidism and poor outcomes of pregnancy, as well as dyslipidemias, atherogenesis, and increased mortality in the long term. We believe these consequences are sufficiently compelling to warrant screening and treatment with levothyroxine when found to halt progression to overt hypothyroidism, and improve symptoms, pregnancy outcomes, lipid abnormalities, and cardiovascular function. Obstetricians & Gynecologists, Family Physicians. After completion of this article, the reader should be able to recall that hypothyroidism is a common disease in women, has many protean manifestations, and can be successfully diagnosed and treated; explain that the condition of subclinical hypothyroidism can be diagnosed and if treated can prevent many untoward complications; and state that there should be heightened awareness of the disease so that proper screening tests can be performed.
Identifying how specific nutrients can impact fertility, pregnancy, and neonatal outcomes will yield important insights into the biological mechanisms linking diet and reproductive health. Our study investigates how dietary vitamin C intake affects various fertility parameters and pregnancy and neonatal outcomes in the guinea pig, a natural model of vitamin C dependency. Dunkin Hartley guinea pigs were fed an optimal (900 mg/kg feed) or low (100 mg/kg feed) vitamin C diet ad libitum for at least three weeks prior to mating and throughout pregnancy. We found that animals receiving the low vitamin C diet had an increased number of unsuccessful matings, a higher incidence of foetal reabsorption, and, among pregnancies resulting in delivery at term, produced fewer offspring. Neonates from mothers on the low vitamin C diet had significantly decreased plasma vitamin C concentrations at birth and exhibited mild growth impairments in a sex-dependent manner. We conclude that a diet low of vitamin C induces a state of subfertility, reduces overall fecundity, and adversely impacts both pregnancy outcomes and growth in the offspring. Our study provides an essential foundation for future investigations to determine whether these findings translate to humans. If so, they could have important clinical implications for assisted reproductive technologies and nutritional recommendations for couples trying to conceive, pregnant women, and breastfeeding mothers.