Computerized analysis of heart rate in fetuses from mothers under levothyroxin treatment

Objective. To investigate fetal heart rate (FHR) of fetuses whose mothers are under levothyroxin treatment for chronic hypothyroidism.Study design. Sixty women under chronic therapy with levothyroxin and 180 controls at 37–39 weeks' gestation were studied by Sonycaid Sistem 8002® computerized cardiotocography (cCTG) for 30 min. cCTG parameters were expressed as mean and SD and the differences tested for statistics by Student t-test. Furthermore, cCTG parameters were related to levothyroxin dose by regression analysis. Significance was assessed at p < 0.05.Results. Computerized cardiotocographic tracings of fetuses from mothers under levothyroxin treatment revealed: significant reduction of baseline FHR (130.1 ± 9.47 vs. 134.9 ± 4.68 bpm); increased number of FHR decelerations greater than 20 bpm (0.2 ± 0.41 vs. 0.05 ± 0.22); reduction of body movements per hour (6.68 ± 11.72 vs. 10.65 ± 11.74); and increased uterine contraction peaks (5.15 ± 4.69 vs. 2.7 ± 2.57). Those fetuses also showed significantly re...