I have been going to the same doctor since my pregnancy began, and I've been told a different due date every time I go. The due dates are not days or weeks apart, they're months! They found two different heartbeats, and a sonogram showed two different babies, so they said I was having twins. Then, when I went back, they said that it was not twins, but just a reflection of the baby. Is there such a thing? The babies were not even the same size in my sonogram pictures. Should I switch doctors or trust the one I have been going to?

Christy

What you describe certainly sounds odd. Some medical professionals have a hard time translating medical terms into plain English. Your doctors may have trouble explaining things to patients in a way that is easily understood. There are, however, a couple of explanations for what you describe. I wish you had indicated how far along you are, because that would help. But, since you didn't, here's my best explanation:

For the widely varying due dates: The first due date we give someone is based on what she tells us about when her last menstrual period started. If the recollection of that date is off, she will be given an inaccurate due date. The second way of determining due date is by physical exam and the size of the uterus. The third is by ultrasound, and this, if done before 20 weeks, is the most accurate.

To see how this works, let's say a woman comes in on 1/1/2000 and says her last period began on 11/17/99. That information would suggest she is just over six weeks pregnant and is due on 8/24/00. Then, in an exam, her uterus feels like it is the size of a nine-week pregnancy; that would change to due date to 8/5/00. Because of this discrepancy, an ultrasound is done; this indicates a 12-week pregnancy and a final -- and most accurate -- due date of 7/16/00. (In such a case, the woman may have misremembered the date of her period, or thought she was having a period when she may actually have had bleeding related to implantation of the pregnancy.)

For the twins that are no longer there: Sometimes twins are conceived and are seen on a very early ultrasound, but one of the twins does not survive and is reabsorbed by the body or miscarried in an episode of vaginal bleeding. On the next visit, if two heartbeats are not heard, another ultrasound will ordered, and it will show only one baby. This happens more often that we used to think, but in the past, we rarely knew when it happened. It is detected more often now simply because early ultrasounds are more common.

This is probably what happened in your case, especially since you said the babies weren't the same size on the first ultrasound. Discrepancy in the size of twins, especially early on, is often an indication that the smaller one will be miscarried. Later in pregnancy, differences in the size of twins have other implications.

Another possible explanation for the "disappearing" twin is that there never were twins in the first place. The person doing or interpreting the ultrasound may have mistaken the yolk sac -- a small circular structure that nourishes the developing embryo in the first few weeks of pregnancy -- for a second baby.

These are just possible explanations for what you describe. Ask your doctor the same question you asked here, and see if you get an explanation that makes sense. If you are not comfortable with your doctor, then by all means seek care elsewhere. Pregnancy is a time of both great excitement and great anxiety, and you must have confidence in the person helping you on this wonderful nine-month journey.