Endocrine Abstracts

Introduction: Thyroid antiperoxidase antibodies above the cut-off value (ATPO +) may increase the risk of maternal-foetal complications and could modify the treatment criteria. The aim of the study is to consider the impact of levothyroxine administration on maternal-foetal complications in ATPO+ pregnant women with delivery in 2016.

Methods: In Leon’s health area (Spain), universal screening for gestational thyroid dysfunction is performed. ATPO + was ≥35 U/ml (Immulite 2,000). The cut-off for subclinical gestational hypothyroidism (HSG) was TSH >3.72 mU/l (Roche kit) The maternal-foetal variables studied were gestational age, birth weight and type of delivery:

-Preterm birth is considered when pregnancy’s completed before week 37.

- Low birth weight is considered <2500 gr.

The qualitative variables were expressed by absolute numbers and percentages, and the quantitative variables in mean and standard deviation. The X2 test was used to evaluate differences between proportions and T student test to compare means. The association among risk factors and treatment was studied by relative risk and confidence interval.

Results: We analysed 1980 deliveries, 22 miscarriages and 18 deliveries outside our hospital. 87 were eliminated by previous treatment with thyroxine. Of 1672 screenings: 142 (8.50%) had ATPO +, 286 (17.11%) HSG and in 55 (3.29%) HSG and ATPO+ coexist. We studied 131 ATPO+ pregnant women: 45% (n=59) of patients received treatment during pregnancy. Of those who received treatment during pregnancy, presented preterm delivery 3.39% vs 11.11% that didn’t receive thyroxine (RR: 0.31, 95% CI: 0.07–1.40). The mean gestational age of the newborns was 39.05 (1.53) weeks, for patients treated with levothyroxine, it increases up to 39.15 (1.4) weeks, slightly higher than those who didn’t receive treatment ((38.97 (1.64) (P=0.50)). We found 6.78% children with weight <2500 gr in patients with treatment and 5.56% in those who weren’t treated (P=1.00). 15 untreated women (20.83%) underwent a caesarean section and 10 treated pregnant women (16.95%) ended their pregnancy as a caesarean section (P=0.84). The average dose of thyroxine was 71.53 μg/day (0.95 μg/kg per day). With this dose, the average TSH at the end was 1.76 mU / l.

Conclusion: According to these results, there is neither positive or negative impact of the administration of levothyroxine to pregnant women ATPO +. There may be a protective tendency on preterm delivery, although larger studies are needed.