我Google的国外网站对HCG的表述，我给稍微翻译下：
Early hCG Levels
In most normal pregnancies, at hCG levels below 1,200 mIU/ml, the hCG level usually doubles every 48-72 hours and normally increases by at least 60% every two days. （1200以下的HCG，每48-72小时翻倍，每两天至少增长60%）
In early pregnancy, a 48-hour increase of hCG by 35% can still be considered normal.（孕早期，48小时hcg有35%的增长也被认为是正常的）
As your pregnancy progresses, the hCG level increase slows down significantly.（hcg的增长会逐渐放慢）
Between 1,200 and 6,000 mIU/ml serum, the hCG level usually takes 72-96 hours to double.（hcg在1200-6000之间，一般需要72-96小时翻倍）
Above 6,000 mIU/ml, the hCG level often takes over four or more days to double.（hcg大于6000，需要超过4天时间翻倍）
In general, when the HCG level reaches 7200 mIU/ml, a yolk sac should be seen.（一般来说，hcg达到7200时卵黄囊可见）
At an HCG level greater than 10,800 mIU/ml, there should be a visible embryo with a heartbeat.（hcg大于10800时，心血管搏动可见）
Pregnancy blood hCG levels are not recommended for testing the viability of the pregnancy when the hCG level is well over 6,000 and/or after 6-7 weeks of the pregnancy. Blood hCG levels are useless for testing the viability of the pregnancy if the hCG level is well over 6,000 and/or after 6-7 weeks days of the pregnancy. In general, after 6-7 weeks the best indication of a healthy pregnancy is a good fetal heartbeat. Instead of the hCG, after 6 weeks or an hCG above 6,000 mIU/cc, the health of the pregnancy can best be confirmed with a sonogram to confirm the presence of a fetal heartbeat. Once a fetal heartbeat is seen, the hCG levels don't tell you much more about the pregnancy viability.（hcg达到6000以上或怀孕超过6-7周时候，不推荐再跟踪HCG。良性的孕程一般在6-7周时，已有心跳。在hcg超过6000或孕6-7周后，监测心跳是比hcg更能说明孕程顺利的方式。心跳可见后，hcg水平将不能代表更多了）
以上。我个人认为这里应该是beta HCG，而不只是HCG。
