University of Oulu

Suvi Turunen, Marja Vääräsmäki, Tuija Männistö, Anna-Liisa Hartikainen, Anna-Maria Lahesmaa-Korpinen, Mika Gissler, and Eila Suvanto. Thyroid. Jan 2019.135-141.

Pregnancy and perinatal outcome among hypothyroid mothers : a population-based cohort study

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Author: Turunen, Suvi1; Vääräsmäki, Marja1; Männistö, Tuija2;
Organizations: 1Department of Obstetrics and Gynecology, PEDEGO Research Unit, Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland
2Northern Finland Laboratory Centre Nordlab, Oulu, Finland
3National Institute of Health and Welfare, Information Services Department, Helsinki, Finland
4Karolinska Institute, Department of Neurobiology, Care Sciences and Society, Stockholm, Sweden
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.2 MB)
Persistent link:
Language: English
Published: Mary Ann Liebert, 2019
Publish Date: 2021-10-29


Background: Maternal hypothyroidism has been associated with adverse pregnancy outcomes. A large nationwide register-based cohort with data on medication purchases was established to study the associations between maternal hypothyroidism, levothyroxine (LT4) use, and pregnancy and perinatal complications.

Methods: The data included all singleton births between 2004 and 2013 (N = 571,785) in Finland. Hypothyroid mothers (n = 16,364) were identified in the Finnish Medical Birth Register. Of these women, 95.8% used LT4 medication, and 37.5% had consistent LT4 use during pregnancy. Hypothyroid mothers were compared to mothers without thyroid disease (N = 550,860) using logistic regression. The main outcome measures were pregnancy and perinatal complications.

Results: Maternal hypothyroidism was associated with several pregnancy and perinatal complications, including gestational diabetes mellitus (odds ratio [OR] = 1.19 [confidence interval (CI) 1.13–1.25]), gestational hypertension (OR = 1.20 [CI 1.10–1.30]), severe preeclampsia (OR = 1.38 [CI 1.15–1.65]), cesarean section (OR = 1.22 [CI 1.17–1.27]), preterm births (OR = 1.25 [CI 1.16–1.34]), large-for-gestational age newborns (OR = 1.30 [CI 1.19–1.42]), major congenital anomalies (OR = 1.14 [CI 1.06–1.22]), and neonatal intensive care unit admission (OR = 1.23 [CI 1.17–1.29]). However, among mothers with consistent LT4 purchases, only the associations between gestational diabetes mellitus (OR = 1.12 [CI 1.03–1.22]), cesarean section (OR = 1.13 [CI 1.06–1.21]), neonatal intensive care unit admission (OR = 1.09 [CI 1.01–1.29]), and large-for-gestational age newborns (OR = 1.26 [CI 1.10–1.45]) and maternal hypothyroidism remained.

Conclusions: Maternal hypothyroidism is associated with several pregnancy and perinatal complications, but consistent LT4 use may reduce many of the risks.

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Series: Thyroid
ISSN: 1050-7256
ISSN-E: 1557-9077
ISSN-L: 1050-7256
Volume: 29
Issue: 1
Pages: 135 - 141
DOI: 10.1089/thy.2018.0311
Type of Publication: A1 Journal article – refereed
Field of Science: 3123 Gynaecology and paediatrics
Funding: This work was supported in part by the Northern Ostrobothnia Hospital District (ST) and the Drugs and Pregnancy project by the THL (National Institute for Health and Welfare), FIMEA (Finnish Medicines Agency and KELA (Social Insurance Institution of Finland) (MG and A-ML-K).
Copyright information: © 2019 Mary Ann Liebert, Inc., publishers. All rights reserved, USA and worldwide. Final publication is available from Mary Ann Liebert, Inc., publishers