High thyrotrophin levels at end term increase the risk of breech presentation

Abstract

Summary Objective To study the relationship between maternal thyrotrophin (TSH) and breech presentation at term. Design Combined data sets of two prospective studies to obtain adequate epidemiological power. Patients One thousand and fifty‐eight healthy pregnant women (58 breech, 1000 cephalic) and 131 women who presented in breech at an obstetrical outpatient clinic. Measurements Maternal thyroid parameters [TSH, free thyroid hormone (FT4), thyroid peroxidase antibody (TPO‐Ab)] and foetal presentation were assessed in both groups between 35 and 38 weeks gestation. Power calculations suggested that at least 148 breech cases were required. Results The characteristics of the women in breech in both samples were similar. Women in breech (n = 58 + 131) had significantly higher TSH (but not FT4) than those (n = 1000) with cephalic presentation (Mann–Whitney U‐test, P = 0·003). Different cut‐offs were used to define high TSH in the 916 TPO‐Ab‐negative women with cephalic presentation: the 90th, 95th and 97·5th percentiles were 2·4 mIU/l (n = 149), 2·7 mIU/l (n = 77) and 3·2 mIU/l (n = 37). The prevalence rates of breech presentation in these women were all higher compared to the prevalence of breech in women below these cut‐offs (df = 1, P < 0·01). The relative risk of the 149 women with a TSH >90th percentile (>2·4 mIU/l) to present in breech was 1·82 (95% CI: 1·30–2·56). Conclusions Women with high TSH at end term are at risk for breech presentation. Substantial evidence for a relation between breech presentation and neurodevelopmental delay exists. As high TSH during gestation has also been linked to poor neurodevelopment, the relation between breech presentation and poor neurodevelopment might be thyroid‐related.

Maternal thyroid function in pregnant women with a breech presentation in late gestation

“…1 There were no differences in any of the baseline demographics of both groups in our study unlike the previous study where there were a significantly higher number of primiparous mothers in the breech group. 2 While having a similar rate of successful ECV to the previous study 3 (55 vs 54%), we were unable to confirm their findings of higher TSH concentrations increasing the risk of ECV failure; however, they did have a significantly higher number of primiparous mothers in their cohort than our study (66% vs 44%, P < 0Á001) which may have impacted on their results.…”

“…This is in contrast to the previous studies from the Netherlands. 1,2 There may be several reasons for the discrepancy in results: in the United Kingdom, a breech presentation identified from 36 weeks onward is considered to be an abnormal position and is actively monitored by community midwives to enable the opportunity for ECV. Our cohorts were identified prospectively during routine clinical practice resulting in a large number of breech presentations all of whom were able to be included in the final analysis irrespective of presentation at the time of delivery; women with breech presentation who had successful ECV were excluded in the previous study.…”

Levothyroxine Treatment in Pregnancy: Indications, Efficacy, and Therapeutic Regimen

“…In contrast, a prospective study of 10,990 women in US and Ireland with biochemical evidence of SH did not reveal excessive adverse pregnancy outcomes [ 45 ]. Recent studies from The Netherlands documented an association between TSH levels exceeding >2.4 mIU/mL between the 35th and 38th week of gestation are associated with the approximately 2-fold increased risk for breech presentation [ 46 , 47 ]. Elevated TSH levels earlier during the pregnancy were not associated with risk of breech presentation.…”

Maternal thyroid function and the outcome of external cephalic version: a prospective cohort study

“…Recently, our research group showed that at 36 weeks gestation women with TSH levels above 2.5 mIU/l are at risk for breech presentation [ 8 , 9 ]. It is stated that fetal movements and mobility are a prerequisite for spontaneous version into the cephalic position [ 10 ].…”