Uteroplacental Hemodynamics during Early Human Pregnancy: A Longitudinal Study

Abstract

Background: To determine normal physiologic changes in the uteroplacental hemodynamics during early placental development in the first trimester of pregnancy. Methods: Sixteen normal singleton pregnancies were included in this longitudinal study. Transvaginal Doppler ultrasonographic examinations of uterine, arcuate, radial and spiral arteries were performed at the 5th, 7th, 8th and 10th completed gestational weeks. Peak systolic velocity (PSV), time-averaged maximum velocity (TAMXV) and the pulsatility index (PI) were measured. Results: Uterine artery PSV, TAMXV and PI remained unchanged from the 5th to the 8th week of gestation. From the 8th to the 10th week, PSV (p = 0.02) and TAMXV (p = 0.005) increased and PI decreased (p = 0.006). Changes in the arcuate arteries were similar to those in uterine arteries. No significant changes in PSV, TAMXV or PI of the radial artery were noticed. Spiral artery PSV (p = 0.02) and TAMXV (p = 0.02) increased from the 5th to the 7th week. Thereafter they remained unchanged. Spiral artery PI decreased from the 5th to the 10th week, (p = 0.004). Throughout the study period, the PSV, TAMXV and PI values were significantly higher in the uterine artery than in the arcuate artery, and in the arcuate artery compared with the radial artery. At the 5th gestational week, no differences in PSV and TAMXV were found between radial and spiral arteries. From the 7th gestational week onwards, PSV and TAMXV were significantly lower in the radial artery than in the spiral artery. However, the PI values in the radial artery were significantly higher compared with those in the spiral artery during the whole study period. Conclusions: Spiral artery impedance decreases and blood flow velocities increase as early as between the 5th and the 7th weeks of gestation. During that period, the uterine and arcuate artery hemodynamics remain unchanged. In the uterine and arcuate arteries, decreases in impedance and increases in absolute velocities are detected after the 8th week of gestation. This delay between the changes in the spiral and uterine arteries may represent the magnitude of the increase of placental volume and spiral arterial involvement which is needed to affect uterine hemodynamics.

Uteroplacental circulation in early pregnancy complicated by threatened abortion supplemented with vaginal micronized progesterone or oral dydrogesterone

“…Impaired function of those vessels can result in further pregnancy complications (i.e., intrauterine growth restriction or pregnancy-induced hypertension). Serial measurements conducted by Makikalio et al (19) demonstrated a gradual decrease in the spiral artery PI at 5-10 weeks of uncomplicated pregnancy (from 0.93 Ϯ 0.3 to 0.67 Ϯ 0.3).…”

Rheological and Physiological Consequences of Conversion of the Maternal Spiral Arteries for Uteroplacental Blood Flow during Human Pregnancy

“…This progressive dilation is reflected in sonographic measurements demonstrating that the peak systolic velocity and pulsatility index are higher in the uterine artery compared to the arcuate artery (Fig. 3) [23].…”

Maternal and perinatal outcome in women with threatened abortion in first trimester

“…18 The association between vaginal bleeding and preterm delivery has also been noted by others. 19 Both Batzofin et al and Williams et al reported that patients with bleeding had double the risk of preterm delivery compared with patients without bleeding. 17,20 The study of Williams et al was limited to first trimester bleeding.…”