I was told by my doctor more than two weeks ago that my HCG levels should double approximately every 48 hours during the early stages of pregnancy. That Monday my HCG level was 172. My doctor said she would be happy if I was at 300 on Wednesday and 600 on Friday. By Wednesday I was over 500, and over 1500 on Friday. Could this be an indication of twins? I haven't taken any fertility drugs, but my maternal grandmother had three sets of twins.
Yes, this is highly suggestive of twins (or more!). Until ultrasound says otherwise, twins should be suspected; however, I've seen many "singleton" babies present in this manner, so ultrasound will be the final call. There is also the phenomenon of the "absorbed" twin, in which twins start out, but one silently miscarries before growing big enough to be seen on ultrasound. The picture this presents is twin-like rises in HCG, but only one baby is seen on ultrasound by seven to eight weeks into the pregnancy. Another phenomenon is a "molar" pregnancy. Once again, ultrasound will dispell this worry.