Do Doctors still go by the first day of your last period to figure the due date if...?

Question

your cycles are longer than 28 days long? Mine are all messed up. Sometimes I have 28 day cycles and sometimes 40 day cycles. How would they figure my due date then? I do track my temps and cervical mucus so I know when I ovulate. We aren't trying for baby #2 until December!

Answer 1

Yes, doctors ALL calculate your due date by counting from the first day of your last period.

However, if you are tracking your temps and cervical mucus (I do this, too) you know that the LMP is not going to be very helpful in calculating the due date.

I took my chart to my midwife and we used it to calculate the due dates of my last 2 babies, they were both born within days of our calculations. If we had used the LMP as a doctor would have, the estimated due date would have been off by nearly 2 weeks.

It pays to track your cycles and be aware of when you ovulate. Just be sure to tell your caregiver if you become pregnant that you are very sure of when you conceived and that the date of your LMP might throw off their calculations if they rely on that alone.

Answer 2

Your due date is an estimate based on your last period, not an actual date. Only 5% of babys actually come on their due dates. Pregnancy is considered to be 10 months (not 9) they consider it 10 because they got from the 1day of lmp - your usually most fertile 2 weeks out- you could have gotten pregnant anywhere from the 1 day till a few days before your next cycle, but you most likely concieved 2 weeks out any how your answer is so they have lead way. It could have been any time between the beginning of one period to the beginning of the next...

Answer 3

I knew the exact day I conceived so my doctor used that to determine my due date. If you know when you ovulated then that would be close to the same idea. Your OB will know how to use that information to calculate a due date. It is just an estimate though, very few women actually go into labor on their due date. So even if you are off a week or 2 it wouldn't be too big of a deal.

Answer 4

I think it depends on the doctor. I was charting my bbt's and I knew the day that I ovulated and conceived, which was about 5 days later than the standard day 14. The doctor didn't seem to care about that much. They just went by the date of the last period.

Answer 5

To begin with they go by the first day of your last period. When you have your dating scan, usually around 12 weeks then can tell exactly how far along you are and get a more accurate due date from that.

Answer 6

Mine went by the last day of my period before my 7 weeks ultra sound and then after the ultra sound he got a more accurate due date

Answer 7

mine measured by an ultrasound to determine the that, because off my messy period cycles so maybe your will do the same is more accurate for us doing it that way instead of by your period since we never have it when we are supposed to

Answer 8

At 1st the doctors will use your the 1st day of the your last period.

When you go for your 1st scan, thats when they can tell you for sure when your due date is, by the size of the baby.
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Answer 9

if you know when you ovulate that is great ..let the doctor know to give you more accurate due date
good luck in ttc

Answer 10

In almost all cases, they use your LMP in conjunction with an early ultrasound to confirm dates with measurements.