Low fetal heart rate

I have had one missed miscarriage where I lost the baby at about 8 weeks in Nov 2008, a chemical pregnancy that resulted in a natural miscarriage at 5 weeks 2days in Jan 2009.  I am pregnant again.  This time my quant was neg. for pregnancy at day 31 since LMP, after not getting a period I went back to get another blood test at day 39 LMP, my quant was 64, then 48 hours later it was 201, then 4 days later 1798.  I got my first ultrasound and the baby measured at 6 weeks 1 day with a heart rate of 96bpm last wed when I should have been 7 weeks and 4 days according to LMP.  My doctor is very concerned I will miscarry again and said the heart rate is low.  What do you think?
Other info:  I tested positive for a simple mutation of the MTHFR gene.  The specialist has me on baby aspirin, prenatal vit, folgard and a progesterone suppository at night.

[Elaine Brown, MD]

Hi!
It sounds to me as though you are on all the proper therapy.  If you were my patient, I would probably use the same medications.
While there are a few studies out there suggesting an increased rate of miscarriage associated with a low fetal heart rate in very early pregnancies, this has not been my experience.  As long as the heart rate jumps up into the normal range (120-170) by 7-8 weeks, I have found that these pregnancies are no more likely to miscarry than those with "normal" fetal heart rates. Actually, in our office, we have reached the point where we call 90 a normal rate in a very early (5-7) week pregnancy.
It sounds to me like you ovulated very late, maybe even cycle day 20-39, which could easily throw your dates off by a week and account for the discrepancy in the ultrasound findings.  I feel optimistic.  I hope they are going to repeat the ultrasound next week, and I hope on that scan the heart rate is nice and speedy.  If so, you have about a 95+% chance that the pregnancy will continue.

Good luck!
Dr B

[zoe5555]

Thank you so much.  I actually had another ultrasound today and the baby has grown perfectly, the little peanut should be at 7 weeks and he or she measured exactly that and the heartrate was up to 128 bpm.  Thanks again!

[KPNYC]

A related discussion, Drop in Fetal Heartbeat was started.