Umbilical Artery Closure in Pregnancy: Understanding Risks & Outcomes

Question
I am 25 years old, this is my 3rd child, 10th pregnancy, had 7 miscarriages.  LMP 11-15-04.  I am now 31 weeks pregnant.  At 30 weeks I had an ultrasound to check the placement of placenta.  During the ultrasound the technician found one of the umbilical arteries is closing off.  Is this the same as SUA?  The baby weighed 4lbs 3ozs at 30 weeks, what can I expect for the duration of my pregnancy and for the birth of my child, will she be low birth-weight?  

Answer
Usually, the sonographer can identify a two vessel umbilical cord (absdence of one umbilical artery), which occurs about once in 500 pregnancies. The cause may be atrophy of the missing vessel. Around 30% of these babies will have structural defects. There is also a strong association between fetal structural anomalies and placental vascular occlusion or thrombosis.  However, I never saw a report of a sonographer seeing the arter in closing off, although the effect is the same.  Also, in spite of the risk, in 25 years of practice, I have not seen any ill-effects due to a single umbilical artery. Certainly, when the baby is born, it should be fully evaluated for any structural effects,  and perinatal examination for any vascular defects should be routine. I would also get a Non Stress test at around 36 weeks gestation to make sure that all is well. The duration of the pregnancy and the delivery should be without problems. Good Luck.