Maternal thyrotrophin in euthyroid women is related to meconium stained amniotic fluid in women who deliver at or over 41 weeks of gestation.

BACKGROUND: Maternal thyroid dysfunction is of known influence on pregnancies in the preterm period. However little is known about its effect on term and post term pregnancies. Meconium stained amniotic fluid (MSAF) is known to occur preferentially in (post)term pregnancies.

AIMS: To assess a possible independent relation between maternal thyroid function and MSAF.

STUDY DESIGN AND SUBJECTS: 1051 women, in whom thyroid function was assessed at each trimester, were followed prospectively (delivery ≥37weeks). We compared the difference in mean TSH and FT4 between women with (152) and without (899) MSAF using one way ANOVA. Thyroid function was assessed in subgroups regarding gestational age. Finally we performed multiple logistic regression analysis with MSAF as dependent variable and TSH as independent variable adjusting for various confounders.

RESULTS: Maternal thyroid function was not associated with the incidence of MSAF when analysing all deliveries ≥37weeks. However, in the "at-risk" group for MSAF (>41weeks), multiple logistic regression showed an independent relation between MSAF and TSH (O.R.: 1.61, 95% CI: 1.10-2.43).

CONCLUSIONS: The present study shows that in women delivering ≥41weeks of gestation, higher TSH is independently related to MSAF.