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How To Determine The Date Of Conception?
Question: I just had my first prenatal visit last week friday. I had my last period on September 14, 2015. However I just had an IUD removed in the beginning of August. I did have a period on August 14th and then on September 14th but the last year I had my IUD a total of 4 periods. My husband and I were trying for a baby and October 14th came and went and I had no period and no signs of pregnancy. On October 22nd I started feeling pregnancy symptoms exhaustion and breast tenderness and Nausea. I took a pregnancy test that night that came out positive and had my blood taken on the 10/24. The result came back 71. The doctor told me I was just about 3 weeks pregnant I am not sure if that includes the 2 weeks prior to ovulation or what. I went for my first prenatal visit last week and the did a general ultra sound on the computer and I ended up having to do a vaginal ultrasound because they couldn't find anything. The ultrasound measured the fetus at six weeks and some days. They are calling it a missed abortion going off my last period date. Could it be possible that my cycle is still off from my IUD and I ovulated later than there for my missed period date could have been later and the baby could be okay. I know I have to wait for Friday to do a full bladder ultrasound. I have a miscarriage for my first pregnancy and I bled the baby out naturally by 9 weeks when the ultrasound was done on the fetus all there was an amniotic sac no egg yolk sac. With this ultrasound there was an amniotic sac, an egg sac and a fetus measuring 6 weeks and some odd days. Is it possible to be misdiagnosed.
Brief Answer:
Unfortunately, it is unlikely you have a viable pregnancy
Detailed Answer:
Hello, and I hope I can help you today.
First, when doctors refer to how many weeks pregnant you are, we usually mean how many weeks since the first day of your last menstrual period. The reason is that we cannot determine your exact date of ovulation or conception, so that is the convention generally used.
If your last real menstrual period was 9/14, then you must have conceived some time in early October. However, the doctor who said you were three weeks pregnant was speaking incorrectly as he was referring to 3 weeks from conception. You really were 5 weeks pregnant since your last period.
In a normal pregnancy, the level of pregnancy hormone is supposed to double every 48 hours and by a HCG hormone level. A transvaginal ultrasound is more accurate than an abdominal one, so the fact that you haven't yet had an abdominal one will not likely change the diagnosis.
Because now in December it has been about 8-9 weeks since your last menstrual period, the fetus should measure about 8-9 weeks and have a heartbeat.
If you did not have a positive pregnancy test in October, then it might be possible you conceived later, but since we know you were pregnant in October that sort-of rules out incorrect dating. The fact that you didn't really menstruate when you had the IUD is just a side effect of the device and has no bearing on the dating of this pregnancy. Once the IUD is removed your normal cycles come right back as the IUD does not stop ovulation.
However, there are exceptions to every rule, and if this is a desired pregnancy there is no reason to rush making a decision about having a procedure right now. It can be normal to not see a heartbeat at 6 weeks, but not at 7 weeks.
The best way to proceed is to repeat the ultrasound in a week or two and see if the fetus grows and develops a heartbeat. If not- then you will have a definite answer.
Even if the fetus has died, the supporting tissue for the pregnancy still makes HCG, so you may still feel pregnant.
So in summary, I advise to hope for the best but prepare for the worst. And there is no harm in waiting to see what happens. However, the likelihood that your dating is wrong is very unlikely in this scenario.
I hope I was able to answer your question today and that this information was helpful. If you need anything further, or find any part of this explanation confusing, please do not hesitate to contact me again.
Sincerely, Dr. Brown
Unfortunately, it is unlikely you have a viable pregnancy
Detailed Answer:
Hello, and I hope I can help you today.
First, when doctors refer to how many weeks pregnant you are, we usually mean how many weeks since the first day of your last menstrual period. The reason is that we cannot determine your exact date of ovulation or conception, so that is the convention generally used.
If your last real menstrual period was 9/14, then you must have conceived some time in early October. However, the doctor who said you were three weeks pregnant was speaking incorrectly as he was referring to 3 weeks from conception. You really were 5 weeks pregnant since your last period.
In a normal pregnancy, the level of pregnancy hormone is supposed to double every 48 hours and by a HCG hormone level. A transvaginal ultrasound is more accurate than an abdominal one, so the fact that you haven't yet had an abdominal one will not likely change the diagnosis.
Because now in December it has been about 8-9 weeks since your last menstrual period, the fetus should measure about 8-9 weeks and have a heartbeat.
If you did not have a positive pregnancy test in October, then it might be possible you conceived later, but since we know you were pregnant in October that sort-of rules out incorrect dating. The fact that you didn't really menstruate when you had the IUD is just a side effect of the device and has no bearing on the dating of this pregnancy. Once the IUD is removed your normal cycles come right back as the IUD does not stop ovulation.
However, there are exceptions to every rule, and if this is a desired pregnancy there is no reason to rush making a decision about having a procedure right now. It can be normal to not see a heartbeat at 6 weeks, but not at 7 weeks.
The best way to proceed is to repeat the ultrasound in a week or two and see if the fetus grows and develops a heartbeat. If not- then you will have a definite answer.
Even if the fetus has died, the supporting tissue for the pregnancy still makes HCG, so you may still feel pregnant.
So in summary, I advise to hope for the best but prepare for the worst. And there is no harm in waiting to see what happens. However, the likelihood that your dating is wrong is very unlikely in this scenario.
I hope I was able to answer your question today and that this information was helpful. If you need anything further, or find any part of this explanation confusing, please do not hesitate to contact me again.
Sincerely, Dr. Brown
Note: Revert back with your gynae reports to get a clear medical analysis by our expert Gynecologic Oncologist. Click here.
Above answer was peer-reviewed by :
Dr. Raju A.T
Answered by
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