OBJECTIVE: To evaluate whether there is an association between maternal thyroid hormone and foetal cephalic head position at term gestation. CONTEXT: Rotation and flexion of the head enables the foetus to negotiate the birth canal. Low-normal range thyroid hormone concentrations in euthyroid pregnant women constitute a risk of infant motor abnormality. We hypothesized that low normal maternal thyroid hormone levels are associated with increased risk of abnormal foetal position at delivery. DESIGN: In 960 healthy Dutch women with term gestation and cephalic foetal presentation, thyroid parameters [foetal T4 (FT4), TSH and thyroid peroxidase antibody] were assessed at 36 weeks of gestation, and related to foetal head position (anterior cephalic vs. abnormal cephalic) and delivery mode (spontaneous vs. assisted delivery). RESULTS: Women presenting in anterior position (n = 891) had significantly higher FT4 levels at 36 weeks of gestation than those with abnormal cephalic presentation (n = 69). There were no between-group differences for TSH. Regression analyses indicated that the risk of abnormal head position decreased as a function of increasing FT4 [single odds ratio (OR) = 0.87, 95% confidence intervals (CI) 0.77-0.98; multivariate OR = 0.88, 95% CI 0.72-0.99)]. A similar inverse relationship between maternal FT4 and risk of assisted delivery was obtained (OR = 0.86, 95% CI 0.79-0.95; OR = 0.91, 95% CI 0.84-0.98). CONCLUSION: The lower the maternal FT4 concentration at 36 weeks of gestation, the higher the risk of abnormal cephalic foetal presentation and assisted delivery.
OBJECTIVE: To evaluate whether there is an association between maternal thyroid hormone and foetal cephalic head position at term gestation. CONTEXT: Rotation and flexion of the head enables the foetus to negotiate the birth canal. Low-normal range thyroid hormone concentrations in euthyroid pregnant women constitute a risk of infant motor abnormality. We hypothesized that low normal maternal thyroid hormone levels are associated with increased risk of abnormal foetal position at delivery. DESIGN: In 960 healthy Dutch women with term gestation and cephalic foetal presentation, thyroid parameters [foetal T4 (FT4), TSH and thyroid peroxidase antibody] were assessed at 36 weeks of gestation, and related to foetal head position (anterior cephalic vs. abnormal cephalic) and delivery mode (spontaneous vs. assisted delivery). RESULTS:Women presenting in anterior position (n = 891) had significantly higher FT4 levels at 36 weeks of gestation than those with abnormal cephalic presentation (n = 69). There were no between-group differences for TSH. Regression analyses indicated that the risk of abnormal head position decreased as a function of increasing FT4 [single odds ratio (OR) = 0.87, 95% confidence intervals (CI) 0.77-0.98; multivariate OR = 0.88, 95% CI 0.72-0.99)]. A similar inverse relationship between maternal FT4 and risk of assisted delivery was obtained (OR = 0.86, 95% CI 0.79-0.95; OR = 0.91, 95% CI 0.84-0.98). CONCLUSION: The lower the maternal FT4 concentration at 36 weeks of gestation, the higher the risk of abnormal cephalic foetal presentation and assisted delivery.
Authors: Simone M Kuppens; Libbe Kooistra; Tom H Hasaart; Riet W van der Donk; Huib L Vader; Guid S Oei; Victor J Pop Journal: BMC Pregnancy Childbirth Date: 2011-01-26 Impact factor: 3.007