What your daughter has probably been diagnosed as is blighted ovum. An anembryonic (without the baby) pregnancy is characterized by a normal-appearing gestational sac, but the absence of an embryo. Normally a gestational sac with a yolk sac appears at about 5 weeks (calculated from your last missed period date) of pregnancy and can be well visualized by 6 weeks on a transvaginal (through a vagina) ultrasound. A pregnancy is anembryonic or blighted ovum, if an ultrasound through vagina reveals a sac with gestational sac diameter greater than 13 mm and no yolk sac, or diameter more than 18 mm with no embryo. Follow-up ultrasound is done after 10 days to verify diagnosis. Normally it is wise to wait until 10-11 weeks of pregnancy for a confirmed diagnosis of blighted ovum or fetal death. Meanwhile monitor the HCG levels at 48 hours levels. If they rise and almost double in 48 hours, then chances of pregnancy carrying forward are high. Take care!
she may be earlier then she expected