Dataset Information

Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence.

ABSTRACT:

Objectives

To evaluate the association between thyroid autoantibodies and miscarriage and preterm birth in women with normal thyroid function. To assess the effect of treatment with levothyroxine on pregnancy outcomes in this group of women.

Design

Systematic review and meta-analysis.

Data sources

Medline, Embase, Cochrane Library, and SCISEARCH (inception-2011) without any language restrictions. We used a combination of key words to generate two subsets of citations, one indexing thyroid autoantibodies and the other indexing the outcomes of miscarriage and preterm birth.

Study selection

Studies that evaluated the association between thyroid autoantibodies and pregnancy outcomes were selected in a two stage process. Two reviewers selected studies that met the predefined and explicit criteria regarding population, tests, and outcomes.

Data synthesis

Odds ratios from individual studies were pooled separately for cohort and case-control studies with the random effects model.

Results

30 articles with 31 studies (19 cohort and 12 case-control) involving 12,126 women assessed the association between thyroid autoantibodies and miscarriage. Five studies with 12,566 women evaluated the association with preterm birth. Of the 31 studies evaluating miscarriage, 28 showed a positive association between thyroid autoantibodies and miscarriage. Meta-analysis of the cohort studies showed more than tripling in the odds of miscarriage with the presence of thyroid autoantibodies (odds ratio 3.90, 95% confidence interval 2.48 to 6.12; P < 0.001). For case-control studies the odds ratio for miscarriage was 1.80, 1.25 to 2.60; P = 0.002). There was a significant doubling in the odds of preterm birth with the presence of thyroid autoantibodies (2.07, 1.17 to 3.68; P = 0.01). Two randomised studies evaluated the effect of treatment with levothyroxine on miscarriage. Both showed a fall in miscarriage rates, and meta-analysis showed a significant 52% relative risk reduction in miscarriages with levothyroxine (relative risk 0.48, 0.25 to 0.92; P=0.03). One study reported on the effect of levothyroxine on the rate of preterm birth, and noted a 69% relative risk reduction (0.31, 0.11 to 0.90).

Conclusion

The presence of maternal thyroid autoantibodies is strongly associated with miscarriage and preterm delivery. There is evidence that treatment with levothyroxine can attenuate the risks.

SUBMITTER: Thangaratinam S

PROVIDER: S-EPMC3089879 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence.

Thangaratinam Shakila S Tan Alex A Knox Ellen E Kilby Mark D MD Franklyn Jayne J Coomarasamy Arri A

BMJ (Clinical research ed.) 20110509

<h4>Objectives</h4>To evaluate the association between thyroid autoantibodies and miscarriage and preterm birth in women with normal thyroid function. To assess the effect of treatment with levothyroxine on pregnancy outcomes in this group of women.<h4>Design</h4>Systematic review and meta-analysis.<h4>Data sources</h4>Medline, Embase, Cochrane Library, and SCISEARCH (inception-2011) without any language restrictions. We used a combination of key words to generate two subsets of citations, one i ...[more]

PMID: 21558126

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Project description:ImportanceMaternal hypothyroidism and hyperthyroidism are risk factors for preterm birth. Milder thyroid function test abnormalities and thyroid autoimmunity are more prevalent, but it remains controversial if these are associated with preterm birth.ObjectiveTo study if maternal thyroid function test abnormalities and thyroid autoimmunity are risk factors for preterm birth.Data sources and study selectionStudies were identified through a search of the Ovid MEDLINE, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials, and Google Scholar databases from inception to March 18, 2018, and by publishing open invitations in relevant journals. Data sets from published and unpublished prospective cohort studies with data on thyroid function tests (thyrotropin [often referred to as thyroid-stimulating hormone or TSH] and free thyroxine [FT4] concentrations) or thyroid peroxidase (TPO) antibody measurements and gestational age at birth were screened for eligibility by 2 independent reviewers. Studies in which participants received treatment based on abnormal thyroid function tests were excluded.Data extraction and synthesisThe primary authors provided individual participant data that were analyzed using mixed-effects models.Main outcomes and measuresThe primary outcome was preterm birth (<37 weeks' gestational age).ResultsFrom 2526 published reports, 35 cohorts were invited to participate. After the addition of 5 unpublished data sets, a total of 19 cohorts were included. The study population included 47 045 pregnant women (mean age, 29 years; median gestational age at blood sampling, 12.9 weeks), of whom 1234 (3.1%) had subclinical hypothyroidism (increased thyrotropin concentration with normal FT4 concentration), 904 (2.2%) had isolated hypothyroxinemia (decreased FT4 concentration with normal thyrotropin concentration), and 3043 (7.5%) were TPO antibody positive; 2357 (5.0%) had a preterm birth. The risk of preterm birth was higher for women with subclinical hypothyroidism than euthyroid women (6.1% vs 5.0%, respectively; absolute risk difference, 1.4% [95% CI, 0%-3.2%]; odds ratio [OR], 1.29 [95% CI, 1.01-1.64]). Among women with isolated hypothyroxinemia, the risk of preterm birth was 7.1% vs 5.0% in euthyroid women (absolute risk difference, 2.3% [95% CI, 0.6%-4.5%]; OR, 1.46 [95% CI, 1.12-1.90]). In continuous analyses, each 1-SD higher maternal thyrotropin concentration was associated with a higher risk of preterm birth (absolute risk difference, 0.2% [95% CI, 0%-0.4%] per 1 SD; OR, 1.04 [95% CI, 1.00-1.09] per 1 SD). Thyroid peroxidase antibody-positive women had a higher risk of preterm birth vs TPO antibody-negative women (6.6% vs 4.9%, respectively; absolute risk difference, 1.6% [95% CI, 0.7%-2.8%]; OR, 1.33 [95% CI, 1.15-1.56]).Conclusions and relevanceAmong pregnant women without overt thyroid disease, subclinical hypothyroidism, isolated hypothyroxinemia, and TPO antibody positivity were significantly associated with higher risk of preterm birth. These results provide insights toward optimizing clinical decision-making strategies that should consider the potential harms and benefits of screening programs and levothyroxine treatment during pregnancy.

Project description:BackgroundAnemia in pregnancy has been associated with a number of adverse birth outcomes, such as low birth weight (LBW) or preterm birth (PTB). However, the evidence from primary studies on anemia in pregnancy with LBW and PTB is contentious. Moreover, a systematic review and meta-analysis to summarize these findings have not been conducted for Ethiopia. This study aimed to synthesize the best available evidence and quantify the strength and direction of the association of anemia in Ethiopia.MethodsThis review examined women with singleton pregnancies with low birth weight (LBW) and preterm birth (PTB). We retrieved studies from PubMed, Wiley, Cochrane databases, and Google Scholar from inception to February 2, 2024. The World Health Organization (WHO) defines anemia in pregnancy as a low blood haemoglobin (Hgb) concentration below 11 g/dl or a hematocrit level of < 33%. When the newborn's weight was below 2500 g, LBW was considered. Preterm birth refers to the birth of a baby before 37 completed weeks of gestation. Meta-analysis was conducted using fixed and random effects models. The degree of heterogeneity, publication bias, and quality of the evidence of studies was assessed.ResultsThere were 35 and 8 studies, with 14,319 and 3,265 respondents included in the meta-analysis for LBW and PTB, respectively. Neonates born to women who had normal Hgb levels were less likely to be LBW [pooled odds ratio (POR) = 0.22, 95% CI: (0.17, 0.28); I2 = 80%] (low-quality evidence). Neonates born to women with normal Hgb levels had a lower risk of PTB [POR = 0.22, 95% CI: 0.18, 0.28; I2 = 19%] (very low-quality evidence). The effect size estimate remained significant after sub-group analysis based on study design and province, except in two retrospective cohort studies for LBW.ConclusionThe findings suggest major implications for strengthening the implementation of nutrition policies to prevent anemia during pregnancy in Ethiopia. Further research is warranted to assess interventions that are effective in combating maternal anemia to reduce rates of LBW and PTB.

Project description:BackgroundLiterature surrounding the association between antidepressant use during pregnancy and miscarriage is conflicting. We aimed to conduct a systematic review and meta-analysis of studies among pregnant women regarding the association between exposure to antidepressants during pregnancy and the risk of miscarriage, compared with pregnant women not exposed to antidepressants.DesignWe conducted a systematic review and meta-analysis of non-randomised studies.Data sourcesWe searched Medline, Embase and PsychINFO up to 6 August 2023.Eligibility criteria and outcomesCase-control, cohort and cross-sectional study designs were selected if they compared individuals exposed to any antidepressant class during pregnancy to comparator groups of either no antidepressant use or an alternate antidepressant.Data extraction and synthesisEffect estimates were extracted from selected studies and pooled using a random-effects meta-analysis. Risk of bias (RoB) was assessed using the Risk of Bias in Non-Randomised Studies of Interventions (ROBINS-I) tool, and heterogeneity assessed using the I2 statistic. Subgroup analyses were used to explore antidepressant classes and the impact of confounding by indication.Results1800 records were identified from the search, of which 29 were included in the systematic review and meta-analysis. The total sample included 5 671 135 individuals. Antidepressant users initially appeared to have a higher risk of miscarriage compared with unexposed individuals from the general population (summary effect estimate: 1.24, 95% CI 1.18 to 1.31, I2=69.2%; number of studies (n)=29). However, the summary estimate decreased when comparing against unexposed individuals with maternal depression (1.16, 1.04 to 1.31; I2=58.6%; n=6), suggesting confounding by indication may be driving the association. 22 studies suffered from serious RoB, and only two of the 29 studies were deemed at moderate RoB.ConclusionsAfter accounting for maternal depression, there is little evidence of any association between antidepressant use during pregnancy and miscarriage. Instead, the results indicate the biasing impact of confounding by indication.

Project description:BackgroundThe effect of being born late preterm (34-36 weeks gestation) on cardiometabolic outcomes across the life course is unclear.ObjectivesTo systematically review the association between being born late preterm (spontaneous or indicated), compared to the term and cardiometabolic outcomes in children and adults.Data sourcesEMBASE(Ovid), MEDLINE(Ovid), CINAHL.Study selection and data extractionObservational studies up to July 2021 were included. Study characteristics, gestational age, cardiometabolic outcomes, risk ratios (RRs), odds ratios (ORs), hazard ratios (HRs), mean differences and 95% confidence intervals (CIs) were extracted.SynthesisWe pooled converted RRs using random-effects meta-analyses for diabetes, hypertension, ischemic heart disease (IHD) and body mass index (BMI) with subgroups for children and adults. The risk of bias was assessed using the Newcastle-Ottawa scale and certainty of the evidence was assessed using the grading of recommendations, assessment, development and evaluation (GRADE) approach.ResultsForty-one studies were included (41,203,468 total participants; median: 5.0% late preterm). Late preterm birth was associated with increased diabetes (RR 1.24, 95% CI 1.17, 1.32; nine studies; n = 6,056,511; incidence 0.9%; I2 51%; low certainty) and hypertension (RR 1.21, 95% CI 1.13, 1.30; 11 studies; n = 3,983,141; incidence 3.4%; I2 64%; low certainty) in children and adults combined. Late preterm birth was associated with decreased BMI z-scores in children (standard mean difference -0.38; 95% CI -0.67, -0.09; five studies; n = 32,602; proportion late preterm 8.3%; I2 96%; very low certainty). There was insufficient evidence that late preterm birth was associated with increased IHD risk in adults (HR 1.20, 95% CI 0.89, 1.62; four studies; n = 2,706,806; incidence 0.3%; I2 87%; very low certainty).ConclusionsLate preterm birth was associated with an increased risk of diabetes and hypertension. The certainty of the evidence was low or very low. Inconsistencies in late preterm and term definitions, confounding variables and outcome age limited the comparability of studies.

Project description:BackgroundHistologic examination of the placenta is often performed after preterm birth. Although placental examination cannot change the index pregnancy outcome, it may inform the risk of adverse outcomes in a subsequent pregnancy. Previous research has examined the association between individual histologic lesions and pregnancy outcomes without consistent results.ObjectiveThis study aimed to determine the independent contributions of the major placental pathology histologic types to recurrent preterm birth.Study designThis was a retrospective cohort study of deliveries at a tertiary care center from January 2009 to March 2018. Individuals with ≥2 births, an index birth of <37 weeks of gestation, and a placental pathology report from the index pregnancy were included. The presence of maternal vascular malperfusion, fetal vascular malperfusion, acute inflammation, and chronic inflammation was extracted from the pathology reports for each index placenta and classified as none, low grade, or high grade. A log-binomial model incorporating all 4 placental pathology histologic types, index gestational age, race, and maternal age was used to estimate the associations between each placental histologic type and risk of recurrent preterm birth. Moreover, 2-way interaction terms were studied among placental histologic types. In addition, 2 stratified analyses were completed on the basis of characteristics of the index preterm birth: (1) by late preterm (gestational age of 34-36 weeks) vs early-to-moderate preterm birth (<34 weeks) and (2) a subgroup analysis of those with spontaneous preterm birth.ResultsA total of 924 pregnancy pairs met the inclusion criteria. Only high-grade chronic inflammation was independently associated with an increased risk of recurrent preterm birth (adjusted risk ratio, 1.37; 95% confidence interval, 1.03-1.81). Stratified analysis by gestational age group demonstrated maternal vascular malperfusion was associated with recurrent preterm birth only among those with early preterm birth (adjusted risk ratio, 1.40; 95% confidence interval, 1.01-1.93). Among participants with spontaneous preterm labor, no association was found between pathology histologic types and risk of preterm birth.ConclusionAmong index preterm pregnancies, high-grade chronic placental inflammation was associated with recurrent preterm birth. Low-grade maternal vascular malperfusion was associated with recurrent preterm birth only among those with an early or moderate index preterm birth (<34 weeks of gestation). These findings may be useful in determining the risk profile for individual patients and may generate hypotheses as to the pathogenesis of recurrent preterm birth.

Dataset Information

Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence.

Objectives

Design

Data sources

Study selection

Data synthesis

Results

Conclusion

Publications

Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence.

Similar Datasets

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