Endocrine Abstracts

Background: Previous studies of association between maternal thyroid autoimmunity and adverse pregnancy outcomes have produced inconsistent results.

Objective: To examine whether thyroid autoimmunity detected at first trimester screening is predictive of a range of adverse obstetric and fetal outcomes.

Patients and methods: We studied 438 women with singleton pregnancies who underwent first trimester screening test between June and July 2014. Women were elegible if fetal gestational age was 10–14 weeks from ultrasound crown-rump length measurement. We evaluated the association between thyroid autoimmunity (positive TPO and/or Tiroglobulin (TG) antibodies] with thyroid function (TSH, free T₄), adverse obstetric outcomes (pregnancy loss after 20 weeks, pre-eclampsia, cesarean section, preterm birth) and adverse neonatal outcomes (birth weight, small size for gestational age (SGA), metabolic complications and neonatal death).

Results: 33 women (7.5%) were excluded because of previous thyroid disease. 72 women showed thyroid autoimmunity (TPO-TG-positive group, 17.8%). TSH was significantly higher in TPO-TG-positive group (median (lower and upper cuartiles) 1.87 (1.27–2.45) vs 1.41 (0.93–1.94) mcU/ml, P<0.01). TSH exceed the 97.5 percentile for our specific late-first trimester limit (3.62 mcU/ml) in 12.5% of TPO-TG-positive group and in 2.1% in women with negative thyroid autoimmunity (P<0.01). In 8.6% of the TPO-TG-positive women, thyroxine treatment was initiated at the end of the first trimester (vs 1.1% in the negative group P<0.01). Adverse pregnancy outcomes occurred in 61 women (17.1%), there were not differences between TPO-TG-positive and negative group. There were no differences in cesarean section neither prematurity. Maternal thyroid autoimmunity did not predict SGA, metabolic complications or neonatal death.

Conclusions: Thyroid autoimmunity provides higher risk for mild abnormalities in thyroid function but does not predict adverse pregnancy outcomes in our cohort.