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.


METHODS
Sixty women under chronic therapy with levothyroxin and 180 controls at 37-39 weeks' gestation were studied by Sonycaid Sistem 8002(R) 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 reduced neonatal weight (2668.2 +/- 766.65 vs. 3215.44 + 523.88 g) and lower 1-min Apgar score (8.6 +/- 0.95 vs. 9.3 +/- 1.11). Regression analysis showed a significant correlation between levothyroxin dose and baseline FHR (r = 0.60; p < 0.0001) and fetal body movements per hour (r = 0.52; p < 0.0001), and an inverse relationship with uterine contraction peaks (r = -0.35; p < 0.006), whilst no correlation was found with the number of FHR decelerations greater than 20 bpm.


CONCLUSIONS
Maternal hypothyroidism and levothyroxin treatment influence FHR and cCTG is a sensible tool to reveal that influence.
Buscicchio
G
G
Department of Clinical Sciences, Polytechnic University Marche, Ancona, Italy.
Gentilucci
L
L
Baldini
E
E
Giannubilo
S R
SR
Tranquilli
Andrea L
AL
D000328:Adult; D015148:Cardiotocography; D005260:Female; D005323:Fetal Monitoring; D005333:Fetus / Q000187:drug effects* / Q000502:physiology; D006340:Heart Rate, Fetal / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012044:Regression Analysis; D013974:Thyroxine / Q000627:therapeutic use*
D013974:Thyroxine