What Does The Following Ultrasound Report Indicate?

hi.. my wives Ultrasonogram report of twin pregnancy says : 1.The uterus is anteverted and is gravid with a single gestational sac. there are two fetus seen within it with normal cardiac pulsation. The fetal heart rate of twin A is 167 bpm and that of twin B is 168 bpm. 2. the NB appears normal. 3. there are two placenta present. One is anterior Grade 0 and away from the Os. another one is?posterior Grade 0 and marginal. 4. The Interamniotic membrane is seen in the present study 5. The gestational age of pregnancy is 13 weeks please help me to understand those. Is there any complicity. I am very tensed