Maternal Hypothyroidism in Early Pregnancy and Infant Structural Congenital Malformations

Abstract

Background. The question is debated on whether maternal hypothyroidism or use of thyroxin in early pregnancy affects the risk for infant congenital malformations. Objectives. To expand the previously published study on maternal thyroxin use in early pregnancy and the risk for congenital malformations. Methods. Data from the Swedish Medical Birth Register were used for the years 1996–2011 and infant malformations were identified from national health registers. Women with preexisting diabetes or reporting the use of thyreostatics, anticonvulsants, or antihypertensives were excluded from analysis. Risk estimates were made as odds ratios (ORs) or risk ratios (RRs) after adjustment for year of delivery, maternal age, parity, smoking, and body mass index. Results. Among 23 259 infants whose mothers in early pregnancy used thyroxin, 730 had a major malformation; among all 1 567 736 infants, 48012 had such malformations. The adjusted OR was 1.06 (95% CI 0.98–1.14). For anal atresia the RR was 1.85 (95% CI 1.00–1.85) and for choanal atresia 3.14 (95% CI 1.26–6.47). The risk of some other malformations was also increased but statistical significance was not reached. Conclusions. Treated maternal hypothyroidism may be a weak risk factor for infant congenital malformations but an association with a few rare conditions is possible.

<p>The chance of a live birth after assisted reproduction in women with thyroid disorders</p>

“…A possible association between hyperthyroidism and hypothyroidism during pregnancy and the risk of different CMs in the offspring has been described earlier,30,60–62 either as a consequence of hormonal imbalances or as a teratogenic effect of anti-thyroid medication in mature pregnancy. Nevertheless, no previous studies have examined if an association between hyperthyroidism and hypothyroidism and CMs persists in women undergoing ART treatment.…”

“…The outcome was biochemical pregnancy, clinical pregnancy, and live birth. An association between female thyroid disorders and the risk of congenital malformation (CM) in the offspring has been described earlier, either as a consequence of the underlying maternal thyroid dysfunction or a teratogenic effect 4,30–32. No previous studies have examined if this is also the case if the pregnancy is ART induced, and we therefore aimed to estimate the risk of any CM in the live-born offspring.…”

Craniosynostosis and risk factors related to thyroid dysfunction

“…Supportive observational epidemiologic data are limited, with the NBDPS offering the largest set of detailed observational data to date that can be used to address this question. Several other epidemiologic studies have examined the association of maternal thyroid disease with birth defects, but sample sizes have been quite limited [Momotani et al, 1984; Khoury et al, 1989; Wing et al, 1994; Chen et al, 2011; Yoshihara et al, 2012; Andersen et al, 2013; Kallen and Norstedt Wikner, 2014]. A large study of Texas births reported lower thyroxine levels in newborn screening bloodspots among infants with craniosynostosis [Hashmi et al, 2012], a finding that could be expected if the mothers were hyperthyroid during pregnancy.…”

Associations between Hypothyroidism in Pregnancy and Adverse Maternal and Neonatal Outcomes: A cohort study

“…12,14,17,18 Some studies have revealed associations with compromised fetal neuropsychological development, a heightened susceptibility to congenital malformations, and increased perinatal mortality. [19][20][21] To date, no previous studies have been conducted in Oman to investigate the implications of hypothyroidism during pregnancy on maternal and neonatal outcomes. Additionally, there is a lack of research originating from other countries in the Middle Eastern region, where population size and pregnancy rates differ considerably compared to Western populations.…”