Expert: Catherine Beier MS CBE - 8/26/2008

Question
Well I'm about as confused as ever. Let me just explain everything in detail. My last 2 periods were June 4 & June 29. They are NEVER early. My 2nd one was lighter than usual, but definitely more than spotting. I had sex on July 12 & 16. I has a very faint positive pregnancy test on July 26th, as well as 3 more in that weekend. I went to the Dr August 1st & had another more noticeable positive test. Calculating with my last period as well as when I had sex, I would be 8 weeks today due April 6. I have been spotting brown blood since this past Friday. No cramping, just brown blood & brown goo. I had a intravaginal sonogram today, could see the baby's heartbeat (but not hear it) she said it had a heart rate of 112 which I though was low but she said it's fine. She did the measurements & said I am 6 wks 0 days. Which would make my conception date July 28...2 days AFTER a positive pregnancy test?! When I pointed that out, she had no explanation of how that is possible. So obviously it would seem to me that I'm 8 weeks like I thought, but the baby is just not the size it should be. And when I look at sonogram pictures online, it definitely looks like 6 week sonograms, not 8 week. Does that mean the baby will probably miscarry since the size isn't matching? And wouldn't it make more since for my Dr to think logically & know I'm actually 8 weeks, just with a 6 week sized fetus? I'm so confused and worried & would appreciate any help. Thanks so much in advance!

Answer
Heather,

I studied the dates and information you provided, and to me, it looks like you are correct that your dates would indicate you should be measuring 8 weeks, not 6.  At first, I'd wondered if your positive results were from an earlier miscarriage from which you may still have had HCG in your system, but when I took all your information into consideration, there wouldn't have been enough time for you to become pregnant again and get a positive HPT when you did.  Your positive results also corresponded well to the dates on which you had intercourse, placing your expected conception right around July 14, exactly two weeks before the one you were given.

The heart rate you gave is also within normal limits for a 6 week fetus (it starts slow, increases, then decreases toward the end of pregnancy), but not an 8 week one.

So, all things considered, the question becomes: why is your baby measuring 2 weeks smaller than expected?   That, coupled with your brown spotting, make me wonder if your progesterone levels are too low and/or your HCG level isn't rising as expected.  Progesterone is the hormone that sustains a pregnancy and if they drop too low, your body will not maintain the pregnancy.  

Your doctor probably isn't listening to you as well as he should if he's just taking the ultrasound results at face value.  Doctors sometimes do this because so many women can't recall their last period and/or when they had intercourse, or because those dates aren't reliable in cases where women have irregular cycles making conception difficult to pinpoint.  They know that early ultrasound is the most accurate way to estimate fetal age, but they also sometimes forget that machines can't tell the whole story or take your individual history into account.

I'm sorry I don't have better news, but the answer at this point is to first check hormone levels, check the rate at which your HCG level is rising (should be doubling every couple of days) and rule out any of those factors.  If they all look fine, then it's a waiting game to see what happens.

The good news is that once the heart starts beating, the risk of miscarriage drops to about 1%.  However, this could be one of the 1% situations.  




I wish you all the best!  Keeping my fingers crossed for you~
Catherine