Prevalence of Thyroid Dysfunction in Women in Early Pregnancy


Objective Recent studies report high rates of thyroid disorders in pregnant women. However, the need for universal thyroid screening remains controversial. Our aim was to estimate the prevalence of thyroid dysfunction (TD) during pregnancy and to analyse the association with maternal age.

Design and methods We conducted a cross-sectional study in a referral centre in collaboration with the primary care units from April 2010 to March 2011. The study included 2509 consecutive pregnant women resident in an iodine-sufficient area, mean age 32 years (range 16–47) who were universally screened for TD in their first trimester (median gestation 8 weeks, range 4–13 weeks). Thyroid-stimulating hormone (TSH) and free T4 (FT4) were analysed during the first antenatal visit. We applied first trimester-specific population-based TSH and FT4 reference ranges.

Results We identified 416 women with positive TD screening [16·6%, 95% confidence interval (95% CI) 15·1–18·0]. Of these, 47 had overt hypothyroidism (1·9%), 90 subclinical hypothyroidism (3·6%), 23 overt hyperthyroidism (0·9%), 20 subclinical hyperthyroidism (0·8%) and 236 had isolated hypothyroxinaemia (9·4%). Applying a logistic regression model, age ≥30 years was not associated with a higher risk of TD [odds ratio (OR) 0·85, 95% CI 0·67–1·08] or hypothyroidism (OR 0·72, 95% CI 0·50–1·06).

Conclusions TD affects one in six pregnant women in an iodine-sufficient population. Maternal age ≥30 years do not increase the risk of TD.


6 Replies

  • One in 6!!!!!!! They have to screen. And remember the links btwn thyroid and autism...

    thanks for the post. We have to screen our daughters.

  • Aspmama, I think women should be screened when they are planning conception and as soon as pregnancy is confirmed.

  • I agree. But until the nhs does it, we have to spread the word ourselves, esp among female close relatives.

  • Pregnancy was when my problems started. You don't often see it listed as a cause though. If you do, they only mention temporary thyroiditis.

  • Winegum, puberty, pregnancy and menopause are common triggers.

  • Yes I know, although not particularly recognised the medical profession. One of my daughter's friends, aged 13, has just been off school for 2 months. She went from hyper to hypo. They diagnosed her with Graves then Hashish, then thyroiditis.

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