Prevalence of Postpartum Thyroid Dysfunction: A Quantitative Review

Estimates of the prevalence of postpartum thyroid dysfunction (PPTD) vary widely because of variations in study design, populations, and duration of screening. Our objective was to estimate the prevalence of PPTD among general and high-risk women, across geographical regions and in women with antithyroid peroxidase antibodies (TPOAbs). We conducted a systematic review and pooled analysis of the published literature (1975-2004), simultaneously accounting for sample size, study quality, percentage follow-up, and duration of screening. Data sources were MEDLINE and the bibliography of candidate studies. Two reviewers independently extracted data. Of 587 studies identified, 21 articles (8081 subjects) met the study criteria. The pooled prevalence of PPTD, defined as an abnormal thyroid-stimulating hormone (TSH) level, for the general population was 8.1% (95% confidence interval CI 6.6%-10.0%). The risk ratios for the development of PPTD among women with TPOAbs compared to women without TPOAbs ranged between 4 and 97 with a pooled risk ratio of 5.7 (95% CI: 5.3-6.1). Global prevalence varied from 4.4% in Asia to 5.7% in the United States. Prevalence among women with type 1 diabetes mellitus was 19.6% (95% CI 19.5%-19.7%). PPTD occurs in 1 of 12 women in the general population worldwide, 1 of 17 women in the United States and is 5.7 times more likely to occur in women with TPOAbs. The high prevalence may warrant routine screening TPOAbs, but the benefits, cost, and risks related to subsequent therapy must be weighed.