1. Slow fetal heart rate may predict pregnancy outcome in first-trimester threatened abortion 
Apichart Chittacharoen, M.D., Yongyoth Herabutya, F.R.C.O.G. 
Fertility and Sterility 
Volume 82, Issue 1, Pages (July 2004)
DOI: /j.fertnstert

2. FIGURE 1
The distribution of the median fetal heart rate according to gestational age.
Chittacharoen. Slow fetal heart rate in threatened abortion. Fertil Steril 2004.
Fertility and Sterility  , DOI: ( /j.fertnstert )