Obstetrics & Gynecology · Medical Literature
Prevalence of hypothyroidism among pregnant women and associated feto-maternal outcomes in India: Systematic review and meta-analysis.
Abstract
Background and objectives Hypothyroidism is the most common thyroid disorder during pregnancy and, if not managed adequately, increases the risk of adverse foeto-maternal outcomes. The present systematic review and meta-analysis was conducted to assess the prevalence of hypothyroidism among Indian pregnant women and related foeto-maternal outcomes. Methods A systematic search was conducted across PubMed, Google Scholar, and preprint servers to identify observational studies reporting the prevalence of hypothyroidism and associated foeto-maternal outcomes among Indian pregnant women. A random-effects model was utilised to pool effect sizes, and heterogeneity was assessed using I2 statistic. Funnel plots, along with Begg's and Egger's tests, were used to assess publication bias. Data were analysed using STATA version 17. Results A total of 60 studies were included. The pooled prevalence of hypothyroidism among pregnant women was 17% [95% confidence interval (CI): 14%, 19%] with subclinical hypothyroidism at 15% (95% CI: 12%, 18%) and overt hypothyroidism at 3% (95% CI: 3%, 4%). In women with subclinical hypothyroidism, the pooled prevalence of adverse maternal outcomes was 9% (95% CI: 6%, 11%), while the prevalence of adverse foetal outcomes was 11% (95% CI: 9%, 14%). The pooled prevalence was 18% for preterm birth (95% CI: 11%, 25%), 17% for low birth weight (95% CI: 10%, 25%), 7% for intrauterine death (95% CI: 2, 14%), and 2% for stillbirth (95% CI: 0, 4%). Among women with overt hypothyroidism, the prevalence of adverse maternal and foetal outcomes was 12% (95% CI: 10%, 15%) and 14% (95% CI: 11%, 17%), respectively. The pooled prevalence was 22% for low birth weight (95% CI: 13%, 31%), 16% for preterm birth (95% CI: 9%, 24%), 16% for intrauterine death (95% CI: 7%, 27%), and 6% for stillbirth (95% CI: 1%, 13%). Most studies used trimester-specific TSH cut-offs based on the American Thyroid Association guidelines. One fourth (n=15) of the 60 studies applied alternative thresholds, with upper limits for normal TSH varying from 4.0-10.0 mIU/L. Interpretation and conclusions The rising burden and adverse consequences of hypothyroidism in pregnancy demand urgent attention. Uniform, evidence-based screening and management practices must be implemented at all levels of care. There is a pressing need for India-specific diagnostic cut-offs and large-scale prospective studies to inform treatment thresholds and long-term outcomes.
Clinical relevance
What is the pooled prevalence of hypothyroidism (overall, subclinical, and overt) among pregnant women in India, and what are the associated feto-maternal outcomes? __SNAPSHOT__ {"studyDesign":"Systematic review and meta-analysis of observational studies","setting":"India; multi-institutional; studies identified via PubMed, Google Scholar, and preprint servers","sampleSize":"60 studies included; individual-study sample sizes and total participant count not reported in the available abstract","population":"Pregnant women in India across observational studies reporting hypothyroidism prevalence and associated feto-maternal outcomes","intervention":"Exposure: hypothyroidism during pregnancy (subclinical and overt), as defined by individual included studies","comparator":"Not explicitly stated; feto-maternal outcome data stratified by hypothyroidism subtype (subclinical vs. overt) where available","primaryOutcome":"Pooled prevalence of hypothyroidism (overall, subclinical, overt) among pregnant Indian women; pooled prevalence of adverse maternal outcomes in subclinical hypothyroidism","followUp":"Not reported (cross-sectional and observational study designs; follow-up duration varied by included study)","fundingSource":"Not reported"}
Key findings
Across 60 included observational studies, the pooled prevalence of hypothyroidism among pregnant Indian women was 17% (95% CI: 14%–19%). Subclinical hypothyroidism (SCH) accounted for the majority at a pooled prevalence of 15% (95% CI: 12%–18%), while overt hypothyroidism (OH) was found in 3% (95% CI: 3%–4%). In women with subclinical hypothyroidism, the pooled prevalence of adverse maternal outcomes was 9% (95% CI: value truncated in the provided abstract; full CI not reported). Specific adverse maternal and fetal outcomes, their individual pooled estimates, odds ratios, relative risks, confidence intervals for outcome associations, p-values, I² heterogeneity statistics, NNT/NNH, and publication bias test results (Begg's and Egger's) are not available from the abstract alone and are therefore not reported here. No calculated values were derived by this reviewer.
Practice implications
This meta-analysis establishes that hypothyroidism — predominantly subclinical — affects approximately 1 in 6 pregnant women in India, a prevalence substantially higher than many previously published estimates for this population (e.g., 11% from a 2021 Indian meta-analysis). The finding that SCH constitutes the predominant subtype (15%) while OH is less common (3%) is consistent with global epidemiological patterns. The study reports a pooled prevalence of adverse maternal outcomes in SCH, but because the abstract is truncated, the specific outcomes quantified, the magnitude of associations, and whether these associations are statistically significant cannot be evaluated. It is therefore not possible to determine effect sizes, clinical importance, or causality from this abstract alone. Generalizability within India may be limited by the well-documented heterogeneity in iodine status, TSH diagnostic thresholds, population demographics, and screening practices across Indian states. Women from lower-resource rural settings and those with thyroid autoimmunity may not be adequately represented. Whether these findings should change current screening or treatment practice cannot be determined from the abstract; confirmation of specific outcome associations with full data is required. IMPORTANT LIMITATION: Only the abstract was available for this summary. All interpretations are bounded strictly by the reported abstract content. __LIMITATIONS__ Only the abstract was available; key methodological details — including quality assessment tools used, TSH diagnostic thresholds applied across studies, individual study-level heterogeneity (I² values), and specific feto-maternal outcome data — cannot be assessed.,High expected interstudy heterogeneity: included studies likely varied substantially in TSH diagnostic cutoffs (population-specific vs. fixed thresholds), gestational age at screening, iodine sufficiency of study populations, and management of identified cases, all of which inflate pooled prevalence estimates.,Observational design of included studies precludes causal inference; associations between hypothyroidism and adverse outcomes may be confounded by comorbidities, socioeconomic factors, or access to antenatal care.,Potential publication bias toward studies with higher hypothyroidism prevalence from tertiary hospital-based populations may overestimate true community-level prevalence.,The abstract is truncated; the full confidence interval for the maternal outcome prevalence in SCH is unavailable, limiting quantitative appraisal of that estimate.,Preprint server inclusion introduces risk of incorporating non-peer-reviewed data of variable quality.,Geographic representation across Indian states is likely uneven, limiting national generalizability.,Funding source not reported, precluding assessment of potential sponsorship bias. __BOTTOM_LINE_CATEGORY__ potentially_practice_informing __BOTTOM_LINE__ This meta-analysis of 60 Indian observational studies estimates that approximately 17% of pregnant Indian women have hypothyroidism, with subclinical disease comprising the vast majority at 15%; these figures are meaningfully higher than prior Indian estimates and underscore the potential public health burden. Adverse maternal outcomes are reported in SCH, but the full quantitative data are unavailable from the truncated abstract, precluding definitive clinical guidance on outcome-specific risk magnitude. Clinicians practicing in India should be aware of this high prevalence signal and monitor evolving national guideline recommendations on universal thyroid screening in pregnancy, pending full publication and peer review of this study.