The trophoblast implantation and placentation during the first trimester of pregnancy has an important role in the further development of the pregnancy. Poor placentation may determine a poor prognosis of pregnancy. In our study we followed the characteristics of placental development with the help of ultrasound by the end of the first trimester of pregnancy. The goal of this study is to develop methods for early diagnosis of high-risk pregnancies. We investigated pregnancies in the first trimester, between 11-13 weeks of pregnancy (148 cases, crown-rump length: 61,3 +/–9 mm). We studied the placental site, placental volume, volume of the gestational sac, the placental cord insertion and its distance to the lower edge (F) and cervical edge of the placenta (C). With color Doppler, we investigated the utero-placental circulation (resistance index in the uterine arteries bilaterally RI-Ut). We followed the further development of these pregnancies and the emergence of pathological cases (spontaneous abortion in the second trimester of pregnancy, premature birth, pregnancy-induced hypertension, intrauterine growth retardation of the fetus, placenta praevia). The group with ratio F/C <0,33 presented smaller placental volume and significantly higher RI-Ut than the control group (ratio F/C> 0,33). We found a strong, statistically significant positive association between the ratio F/C <0,33 and development of pathological pregnancies (46,15% vs. 17,64%, RR = 3,07, p <0,05, Chi-test).
Keywords: placenta, umbilical cord, high risk pregnancy