The effect of anatomical placental location on the third stage of labor.

According to the lower uterine segment and trophotropism hypotheses of placental implantation, placentation occurs in uterine segments with a high blood supply. The present study was designed to determine the clinical implications of these hypotheses by assessing the dynamics of the third stage of labor. Two-hundred and ninety-two prospectively followed pregnant women were assessed at the time of delivery. The uterine locations of the placentas were determined according to the position of the main placental volume and mass under a sagittal view obtained using a centrally located ultrasonography probe. Depending on the location of the placental mass, the patients were assigned to three groups: anterior, posterior, and fundal. The placenta was located in the anterior, posterior, and fundal wall in 52.7% (154/292), 37.7% (110/292), and 9.6% (28/292) of cases, respectively. The duration of the third stage of labor was 6.26 ± 3.89, 6.47 ± 3.68, and 7.42 ± 3.67 min in the anterior, posterior, and fundal placental groups, respectively (P = 0.06). The placenta was separated peripherally in 25% (n = 73) of the patients in each group and centrally in 75% (n = 219). The delta hematocrit value (hematocrit change) was 2.99 ± 4.39, 3.15 ± 6.52, and 2.76 ± 3.04 in the anterior, posterior, and fundal groups, respectively (P = 0.99). This study showed that the location of the placenta did not affect the dynamics of the third stage of labor. Clin. Anat. 30:508-511, 2017. © 2017 Wiley Periodicals, Inc.