"...It is recommended that umbilical artery Doppler should be the standard of practice in managing high-risk pregnancies complicated with fetal growth restriction and preeclampsia (level A recommendation). However, its use should be integrated with other current fetal monitoring tests (levels B and C recommendation). The overall management should also be guided by additional clinical considerations such as the gestational age, fetal and maternal status, and obstetrical conditions..."
http://www.ncbi.nlm.nih.gov/pubmed/21048454
So in subsequent pregnancies, your docs will likely be doing an ultrasound examination of the uterine arteries, and probably more than one, so they can keep an eye on it. The test is a second-hand way to figure out some things about the depth of implantation of the placenta. It's not a perfect test, which is why they say to couple it to other bits of information, and some people can have iffy Dopplers and good pregnancies or vice versa. Dopplers can also show improvement as the pregnancy progresses. But it is a help for picking out the pregnancies to watch more closely.
There's still no data suggesting Dopplers are of any use whatsoever in a normal low-risk pregnancy, but we're not having those sorts of pregnancies.
