OUDE Hypoforum

Clin Endocrinol (Oxf). 2009 Mar 6. [Epub ahead of print] Links
Maternal thyroid hormone concentration during late gestation is associated with foetal position at birth.Wijnen HA, Kooistra L, Vader HL, Essed GG, Mol BW, Pop VJ.
Dept of Clinical Health Psychology, University of Tilburg, The Netherlands.

Summary 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 for infant motor abnormality. We hypothesized that low normal maternal thyroid hormone levels are associated with increased risk for abnormal foetal position at delivery. Design In 960 healthy Dutch women with term gestation and cephalic foetal presentation thyroid parameters (FT4, TSH and TPO-Ab) were assessed at 36 weeks' gestation, and related to foetal head position (anterior cephalic versus abnormal cephalic) and delivery mode (spontaneous versus assisted delivery). Results Women presenting in anterior position (N=891) had significantly higher FT4 levels at 36 weeks' gestation than those with abnormal cephalic presentation (N=69). There were no between-group differences for TSH. Regression analyses indicated that the risk for abnormal head position decreased as a function of increasing FT4 (single OR = .87 [95% CI .77 to .98]; multivariate OR = .88 [95% CI .72 to .99]). A similar inverse relationship between maternal FT4 and risk for assisted delivery was obtained (OR = .86, 95% CI .79 to .95; .91, 95% CI: .84 to .98). Conclusion The lower the maternal FT4 concentration at 36 weeks' gestation, the higher the risk for abnormal cephalic foetal presentation and assisted delivery.