low hcg levels

  I am 7 weeks pregnant (LMP) from a Pergonal cycle with hcg shot on 2/10.
  At 4w3d my hcg was 130, rising to 570 at 5w.  By 5w4d my hcg level had only
  risen to 1,450 but a gestational sac was seen. Now at 6w4d, hcg level is
  only 4,400.  However, a heartbeat was seen and the CRL of the fetus (or
  whatever it is at this stage) measured 2.9 which correlated to 5w6d.
  My physician is concerned but encouraged by the fetal development.
  What are the realistic chances this pregnancy is viable?  Is a chromosome
  abnormality the only explanation for low hcg levels and a slow doubling
  rate?  I am 38.
  Thank you for your assistance.

  
  What

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Dear Laura:
The pregnancy by definition is viable: there is a fetal heartbeat. The outlook for a continuing pregnancy when the heartbeat has been identified is 90-92%.
hCG doubles approximately every 2 days: there is a range of increase between 1.66 and 2.33. Laboratory values are set to include 95% of the population: thus, there is a 1/20 chance that a laboratory value that falls outside the "normal range" is meaningless.
Keywords: low hCG, ultrasound shows heartbeat
This information is provided for education purposes and is not a medical consultation. If you have specific questions, please speak with your physician.