Ipotiroidismo subclinico materno come fattore di rischio per i difetti congeniti settali

Background: Maternal clinical and subclinical hypothyroidism is linked with an increased risk of fetal cardiac structural anomalies. The report of the National Registry of Neonatal hypothyroidism support this finding allowing evidence of an increased incidence of these anomalies in neonates with congenital hypothyroidism. Objective of the study : The identification of a correlation between congenital cardiac anomalies and maternal clinical and subclinical hypothyroidism. Methods: A) With a retrospective study on the National Registry of Congenital hypothyroidism the incidence of congenital heart defects has been evaluated. Furthermore the risk of specific cardiac septal defects was calculated when maternal thyroid function was reduced or a goiter present. B) The evaluation of the risk for cardiac septal defects was then evaluated with a retrospective study identifying in patients with hypothyroidism in treatment before and during pregnancy. C) With a case control study maternal thyroid function has been evaluated at delivery in fetuses with and without specific septal defects. Results : In the population of neonates with Congenital Hypothyroidism, the frequency of maternal hypothyroidism or goiter was significantly increased when cardiac septal defects were identified (17.1 %) versus Isolated neonatal hypothyroidism without congenital anomalies (6.3%, p=0.02), with other kind of cardiac defects (2.4%, p=0.04), with other kind of congenital anomalies (1.7%, p=0.01). These differences give an estimation of increased risk for cardiac septal defects in neonatal hypothyroidism 3 times higher if the mother has hypothyroidism or goiter (OR=3,1; I.C. 95%: 1,11-8.17). Taking care only for interventricular septal defects, this risk increases up to six times (OR=5,98; I.C.: 1,5-21,5). Analyzing 1007 neonate that underwent echocardiography during pregnancy 85 of these showed congenital cardiac disease. The frequency of maternal hypothyroidism in treatment was similar in neonates with (4/85= 4,7%) and without (38/922=4,1%).congenital cardiac disease. In the case control study 93 patients have been recruited (45 cases and 48 controls). Analyzing the results of thyroid functional test at delivery mothers of cases with septal defects showed mean values of TSH significantly higher than those of controls and other cardiac defects (p= 0.02). Taking the upper level of normality for TSH as 2.5, if the mother has a TSH ⠥ 2,6 μUI/ml the risk of cardiac septal defects is three time higher (OR=2,9; I.C. 95%: 0,5-22,8) versus the normal population. Conclusions: Maternal hypothyroidism in the first weeks of pregnancy might play a significant role in the appearance of fetal cardiac septal defects. This risk seems to be 6 times higher in congenital hypothyroidism, and three times higher in normal population when TSH values are higher than the upper limit of normality. When maternal hypothyroidism is treated no increase in the incidence of septal defects is noted.