Introduction: With a prevalence of 2.5-5% in the United States, thyroid disease is the second most frequent endocrinopathy that complicates pregnancy. Furthermore, little and controversial evidence relates hypothyroidism during pregnancy with deleterious maternal and perinatal effects. Thus, it is important to recognise the outcome differences in women with pregestational hypothyroidism (PGH) and gestational hypothyroidism (GH).Methods: We used a retrospective cohort in a Health Provider Institution (HPI) with PGH, GH and TSH results noted in the clinical charts. The following maternal and perinatal outcomes were examined: threatened miscarriage, miscarriage, gestational hypertension, preeclampsia, placental abruption, premature labour, fetal obitus, breech presentation, C-section, postpartum haemorrhage and low birth weight. We compared outcomes between patients with PGH vs GH and the subtype of hypothyroidism (clinical, subclinical and controlled). Results: Out of 337 women pregnant between June 2009 and December 2011, 67 had PGH. TSH lowered during the first and third trimester in both groups. The BMI in patients with PGH is significantly higher than in GH (p=0.04). There is a statistically significant difference between the hypothyroidism subtypes (clinical, subclinical and controlled) in patients with GH and PGH in the first and second trimester (p<0.05). Regarding maternal and perinatal outcomes none of them showed a statistically significant difference (p>0.05).Conclusion: There were no significant differences in the maternal-perinatal outcomes in patients with GH versus PGH, with both groups on thyroid hormonal replacement therapy. These results suggest that independently of the time of diagnosis, it is imperative to treat the disease early to prevent or reduce complications.
