Akhtar, M. A., Agrawal, R., Brown, J., Sajjad, Y., & Craciunas, L. (2019). Thyroxine replacement for subfertile women with euthyroid autoimmune thyroid disease or subclinical hypothyroidism. The Cochrane Database of Systematic Reviews, 6(6), CD011009. https://doi.org/10.1002/14651858.CD011009.pub2
Akhtar MA, Agrawal R, Brown J, Sajjad Y, Craciunas L. Thyroxine replacement for subfertile women with euthyroid autoimmune thyroid disease or subclinical hypothyroidism. Cochrane Database Syst Rev. 2019;6(6):CD011009. doi:10.1002/14651858.CD011009.pub2
Akhtar, M. Ahsan, et al. "Thyroxine replacement for subfertile women with euthyroid autoimmune thyroid disease or subclinical hypothyroidism." The Cochrane Database of Systematic Reviews, vol. 6, no. 6, 2019, pp. CD011009.
Thyroxine may give similar IVF births with thyroid antibodies alone
Thyroxine may give similar live birth rates in antibody-positive women with normal thyroid function, a Cochrane review of randomized IVF or ICSI trials found. Across two trials of 686 women, evidence suggested live birth in 31 out of 100 without thyroxine and 26 to 40 out of 100 with it. One small trial in subclinical hypothyroidism suggested a possible gain.
Key Findings
Live birth rates in two trials of 686 women with thyroid autoimmunity and normal thyroid function may have been similar with and without thyroxine (risk ratio 1.04, 95% CI 0.83 to 1.29).
In those women, evidence suggested live birth chances of 31% without thyroxine and 26% to 40% with it; miscarriage may have been similar (risk ratio 0.83, 95% CI 0.47 to 1.46).
One trial of 64 women with subclinical hypothyroidism, with or without thyroid antibodies, suggested thyroxine may have improved live birth (risk ratio 2.13, 95% CI 1.07 to 4.21; low-quality evidence).
In that trial, evidence suggested live birth chances of 25% without thyroxine and 27% to 100% with it; miscarriage may have been similar (risk ratio 0.11, 95% CI 0.01 to 1.98).
Preterm births, thyroxine versus control: 0 of 32 versus 1 of 32 in subclinical hypothyroidism, and 21 of 300 versus 19 of 300 with thyroid antibodies (one trial each).
Interpretation
This Cochrane systematic review combines randomized controlled trials. The four trials enrolled women having IVF or ICSI, and the review did not assess natural conception. The trials had low risk of bias overall. The authors still rated the evidence very low to low quality because each finding came from one or two small trials with wide confidence intervals. They drew no clear conclusions. The review used data from three trials and pooled only two, as populations and thyroxine regimens differed. In the subclinical hypothyroidism trial, control-group women who developed hypothyroidism received thyroxine, which the authors note might have skewed results. No trial reported other adverse outcomes.
RRM Context
Restorative reproductive medicine asks why conception has not happened. The trials sat inside IVF and ICSI cycles, which proceed without answering that question. The review's background associates thyroid antibodies with miscarriage, including after spontaneous conception. The British Thyroid Association suggests thyroid tests for women seeking fertility treatment, the review reports. The review describes TABLET, a trial of 952 women with thyroid antibodies and recurrent miscarriage or infertility. Its authors concluded that thyroxine did not result in a higher live birth rate than placebo among those with normal thyroid function.
Our editorial summary of this paper, not the article's abstract.
Abstract
Background
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.
Objectives
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.
Search Methods
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.
Selection Criteria
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.
Data Collection and Analysis
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.
Main Results
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' Conclusions
We could draw no clear conclusions in this systematic review due to the very low to low quality of the evidence reported.
