Nifedipine therapy for preterm labor: effects on placental, fetal cerebral and atrioventricular Doppler parameters in the first 48 hours.
OBJECTIVE
To assess the effect of nifedipine tocolysis on Doppler parameters of the uterine, umbilical and fetal middle cerebral arteries and atrioventricular valves in the first 48 h of therapy.


METHODS
Doppler waveforms of uterine, umbilical and middle cerebral arteries and both atrioventricular valves were measured from 28 pregnant women and fetuses prior to and during nifedipine therapy for preterm labor. Maternal and fetal heart rates (FHR), maternal systolic and diastolic blood pressure, and the Doppler pulsatility index (PI) of the uterine, umbilical and middle cerebral arteries were measured. The cerebroplacental ratio (middle cerebral artery PI/umbilical artery PI) was calculated. The total time velocity integrals (TVIs) of tricuspid and mitral valves and their E- and A-wave peak velocity ratio (E/A) were measured. Friedman repeated-measures analysis of variance was used to compare the variables before and after nifedipine therapy. If significant differences were found, Wilcoxon's signed ranks test was used to analyze the difference between the two variables. A P-value of < 0.05 was considered significant.


RESULTS
Nifedipine maintenance was associated with a significant decline in maternal systolic and diastolic blood pressure after 24 h, while maternal heart rate and FHR were unaffected. The uterine artery PI had decreased significantly at 24 and 48 h, while the umbilical artery PI did not change significantly. The middle cerebral artery PI had decreased significantly at 24 and again at 48 h. A significant fall in the cerebroplacental Doppler ratio was maintained beyond 24 h. The mean E/A values, TVIs and TVI x FHR values at 24 and 48 h were unchanged from the baseline values.


CONCLUSIONS
Nifedipine maintenance tocolysis is associated with a significant decline in uterine artery and middle cerebral artery Doppler indices 24 h after the first dose. Fetal cardiac diastolic function is unaffected and the significant redistribution observed after 24 h is likely to be attributable to altered cerebral blood flow.
Dokuz Eylul University School of Medicine, Department of Obstetrics and Gynecology, Izmir, Turkey. serkan.guclu@deu.edu.tr
S
S
Guclu
M
M
Gol
U
U
Saygili
N
N
Demir
O
O
Sezer
A A
AA
Baschat
D000328:Adult; D000704:Analysis of Variance; D001158:Arteries / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D003971:Diastole; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006351:Heart Valves / Q000000981:diagnostic imaging / Q000187:drug effects / Q000196:embryology; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000196:embryology; D009543:Nifedipine / Q000627:therapeutic use*; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging / Q000517:prevention & control*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011673:Pulsatile Flow / Q000187:drug effects; D013997:Time Factors; D015149:Tocolytic Agents / Q000627:therapeutic use*; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000187:drug effects*; D014599:Uterus / Q000098:blood supply / Q000000981:diagnostic imaging / Q000187:drug effects
D015149:Tocolytic Agents; D009543:Nifedipine