Once you are pregnant, Arizona Center for Fertility Studies will do all your OB ultrasounds at no charge until 14 weeks of pregnancy; and then you must go for continued care with your OB/GYN. Those ultrasounds usually start at about 5 1/2 to 6 1/2 weeks of pregnancy, and are done every 1-2 weeks afterwards depending on the couple and the circumstances.
Fetal heart tones generally can be seen right after 6 weeks, therefore, unless the woman is at increased risk of an ectopic or tubal pregnancy, from prior pelvic infections or tubal surgery, the initial ultrasound is done at about 6 1/2 weeks to assure that we can see the early fetal heart tones (FHT).
If the patient is at risk for an ectopic pregnancy, the initial ultrasound is done at 5 1/2 to 6 weeks, to document an intrauterine pregnancy. Although it is too early to see a heartbeat, at least there is confirmation that the pregnancy is in the right place and the woman is not at risk of a tubal pregnancy being "missed" and increasing her potential of it rupturing. A ruptured tube requires emergency surgery and can result in a decreased chance of being able to save the involved tube.
A point that needs clarification is how to tell how far along an early pregnancy is? There are two distinctions.
Pregnancy is either figured from a woman's last menstrual cycle (LMP) or from ovulation, which is generally two weeks later. Therefore, a woman can either be 8 weeks pregnant, from her last LMP, or 6 weeks "gestation" if calculated from when it was thought that she ovulated.
Common conventional thinking is to calculate how "pregnant" a woman is from her last LMP. Therefore, in the above example, the woman is 8 weeks pregnant (but 6 weeks gestation). A 40 week pregnancy is based on these calculations but pregnancy is also said to be nine months or 10 lunar months of 4 weeks each. A bit confusing when you think about it.
At Arizona Center for Fertility Studies, we figure how far a woman is pregnant from her ovulation, since in almost every instance, we know when she ovulated because it was tracked with ultrasound or triggered with hCG (Ovulatory dysfunction), and then add 2 weeks to roughly calculate her LMP. To figure out when the baby is due - add 7 days to the LMP and subtract 3 months. Unfortunately, only 5% of women deliver on their due date.
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Once FHTs are seen, ultrasound generally is done every 2 weeks until 12-14 weeks to insure that the pregnancy is developing normally and "make it all real".
At the end of the rest trimester (12 weeks) the couple is sent back to their OB/GYN and/or are referred to an OB (if they do not have one) for continuing obstetrical care. If the couple would like, because of needing reassurance that everything is alright or just wanting to marvel at their baby growing, then additional ultrasounds are gladly done every week until 12-14 weeks of pregnancy.
At that point, the baby is getting too big to be completely seen on ultrasound; and although we hate to see you go, you need to see "a real doctor" for OB care.
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