Abnormal thyroid function parameters in the second trimester of pregnancy are associated with breech presentation at term: a nested cohort study.

OBJECTIVE: Thyroid dysfunction has been described as a possible risk factor for having an abnormal fetal position at birth. In this study we aim to determine the association between thyroid function in early pregnancy and breech presentation at term. STUDY DESIGN: We used data from the Amsterdam Born Children and their Development (ABCD) cohort. 3347 pregnant women were included between January 2003 and March 2004 in Amsterdam, the Netherlands. Thyroid function tests were performed between 5 and 37 weeks gestational age (median 12.9 weeks). The main outcome measure was the association between thyroid function in early pregnancy and breech presentation at term. Univariate and multivariate analysis were performed to determine the association between thyroid function and breech presentation. RESULTS: Increased TSH in pregnancy, defined as thyroid stimulating hormone (TSH) >97.5th percentile (>3.53mIU/L), was associated with a higher risk for breech presentation at term (aOR 2.32, CI 1.1-4.8, p=0.02) compared to euthyroidism (TSH between 2.5th and 97.5th percentile). After exclusion of overt hypothyroidism and hyperthyroidism the aOR was 2.34 (CI 1.1-5.0, p=0.03). Trimester specific analysis showed a significant association of increased TSH levels (>3.68mIU/L) in the second trimester with breech presentation (aOR 3.7, CI 1.7-7.8, p=0.001). In the second trimester low free thyroxine (FT4) <2.5th percentile (<6.7pmol/L) was also associated with breech presentation (aOR 2.5, CI 1.0-6.3, p=0.04). CONCLUSIONS: Increased TSH and decreased FT4 in the second trimester of pregnancy are associated with an increased risk for breech presentation at term. The association of abnormal thyroid parameters in the first of third trimester is still unclear.

First trimester PAPP-A MoM values predictive for breech presentation at term of pregnancy.

INTRODUCTION: Our aim was to state the role of first trimester pregnancy-associated plasma protein A (PAPP-A)-multiple of the median (MoM) value as a predictor for breech presentation at term of pregnancy. MATERIALS AND METHODS: In this retrospective study, we present data for 1100 singleton full-term deliveries that took place in a third-level hospital setting in northeast Italy between January 2004 and July 2007. For each case, PAPP-A, free beta-human chorionic gonadotropin and nuchal translucency were measured during prenatal trisomies screening (between 11 weeks and 13 weeks and 6 d). A wide range of predictive factors for breech presentation at term of pregnancy and other confounding elements were considered. RESULTS: Of the 1100 singleton deliveries at term considered in our study, 40 babies were in breech presentation. Using bivariate analysis and multivariate logistic regression, a lower PAPP-A MoM than 0.63 (first quartile of our distribution) in the first trimester (OR 2.41, CI.95 1.25-4.67), and placental index at term higher than the median value (OR 2.04, CI.95 1.00-4.17) were proven to be associated with breech presentation at term. CONCLUSIONS: A low PAPP-A during the first trimester was a predictive factor for breech presentation at term of pregnancy. Acknowledging and acting on this predictor could enable improved management of breech foetuses in the future.

Maternal thyroid hormones in early pregnancy and risk of breech presentation.

OBJECTIVE: To evaluate the relationship between breech presentation at term (>/= 37 weeks of gestation) and maternal thyroid hormone activity in early gestation. METHODS: We conducted a case-control study of thyroid hormone activity in 179 women who delivered a live term infant in breech presentation (cases) and 849 women who delivered a live term infant in cephalic presentation (control subjects). We used serum samples from prenatal screening at 15 to 16 weeks of gestation in 2006 and 2007 in Edmonton, Alberta. Maternal free thyroxin (fT4) and thyroid-stimulating hormone (TSH) were assayed. Logistic regression was used to estimate the odds of breech presentation in relation to the levels of thyroid hormones while controlling for potential confounders. RESULTS: There were no significant differences between the breech and cephalic groups when comparing fT4 levels (OR 0.94 per pmol/L; 95% CI 0.88 to 1.00) or TSH levels (OR 1.16 per mU/L; 95% CI 0.97 to 1.38) levels, after adjustment for all potential confounders. Segregating fT4 and TSH into quintiles showed the same pattern. Neither hypothyroidism nor hyperthyroidism was associated with risk of breech presentation. CONCLUSION: Our results provide evidence that maternal thyroid hormone levels at 15 to 16 weeks of gestation are not related to risk of breech presentation at birth in term infants.