OBJECTIVE: To estimate the possible association between spontaneous early preterm delivery and maternal thyroid dysfunction in early pregnancy.
METHODS: Maternal serum concentrations of thyroid-stimulating hormone (TSH), free thyroxine, antithyroperoxidase, and antithyroglobulin antibodies at 11–13 weeks of gestation were compared in 102 singleton pregnancies, resulting in spontaneous delivery before 34 weeks and 4,318 normal pregnancies delivering after this gestation.
RESULTS: In the preterm delivery group, compared with the normal outcome group, there was no significant difference in antithyroid antibody positivity (16.7% compared with 16.8%). In the antithyroid antibody-negative pregnancies in the preterm delivery group, compared with the normal outcome group, the median free thyroxine multiple of the median was reduced (0.94 compared with 0.99 multiple of the median, P<.001), but the median TSH multiple of the median was not significantly different (0.99 compared with 1.01 multiple of the median, P=.331).
CONCLUSION: In pregnancies resulting in spontaneous early preterm delivery, there is no evidence of increased prevalence of antithyroid antibody positivity or maternal thyroid dysfunction at 11–13 weeks.
LEVEL OF EVIDENCE: II
Spontaneous early preterm delivery is not associated with maternal thyroid dysfunction in early pregnancy.
From the Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK; the Department of Fetal Medicine, University College Hospital, London, UK; and Unidad Medicina Fetal, Centro Sanitario Virgen del Pilar, San Sebastián, Spain.
See related article on page 287.
Supported by a grant from The Fetal Medicine Foundation (UK Charity No. 1037116). The assays were sponsored by PerkinElmer, Inc, Wallac Oy, Turku, Finland.
The authors thank Ms. Tracy Dew at the Department of Clinical Biochemistry at King's College Hospital, London, for performing the assays.
Corresponding author: Kypros H. Nicolaides, MD, Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, Denmark Hill, London SE5 9RS, UK; e-mail: firstname.lastname@example.org.
Financial Disclosure The authors did not report any potential conflicts of interest.