How are you calculating your due date?

lizbethwalker · July 2011

I know that doctors and a lot of other people go by your LMP but what if I know the day we conceived? Should I go by that? I have a feeling I might get a funny look if I tell the doctor that so I'm tempted to give them they day we conceived as my LMP date.

roxyu · July 2011

Last time I told them my LMP, but told them I ovulated late and believed I should be due on X date. They measured DD and said she was measuring ahead 2 days of my estimate and changed it to that date. I'll likely do the same at my first appt tomorrow!

BuggyLove · July 2011

How long was your cycle? If it was less than 35 days, it's not going to be a big enough difference that you need to try to give some sort of exact calculation. If your cycle was like 40+ days (so then standard calculations put you farther along than you actually are), then just talk that through with your doctor.

You wouldn't give your assumed conception date as an LMP because then you'd be putting yourself further along than you actually are. ETA: Oops -- meant farther behind!

Did you do fertility treatments? That's the only way you can know for sure the date of conception (obviously you can know when you ovulated by charting or monitoring) so I think you should just give them the date of LMP, tell them why you think it matters (ie. long cycle) and see if they want to do an early u/s for dating.

greeneyed_bride · July 2011

lizbethwalker:
I know that doctors and a lot of other people go by your LMP but what if I know the day we conceived? Should I go by that? I have a feeling I might get a funny look if I tell the doctor that so I'm tempted to give them they day we conceived as my LMP date.

That doesn't make any sense. Then they would think that you were two weeks behind where you actually are. (When a pregnant woman is 6 weeks pregnant, the embryo is actually only 4 weeks old, since you're obviously not pregnant from the first day of your period until you ovulate.)

Because I track my cycles, I know exactly when I ovulated (which is two days later than the "average" ovulation date of 14 days after your period starts), so I know that my real due date is 2 days later than the due date my doctor told me, but it doesn't really matter, since babies rarely come on their due dates anyway.

When you say you know the day you conceived, do you mean you know the day you ovulated or the day you had sex? Sperm can live in your body for up to 5 days, so the day you have sex might not actually be the day you conceived.

BigIsland07 · July 2011

I charted with both DS #1 and this one as well. I gave them my LMP, but also told them when I ovulated and that I'd been charting. They based my appointments for both babies on my O date. With the first, I was accurate. TBD on the others.

lizbethwalker · July 2011

When you say you know the day you conceived, do you mean you know the day you ovulated or the day you had sex?

We know when both took place. Since I had my first my cycle has been very average and predictable.

greeneyed_bride · July 2011

lizbethwalker:

When you say you know the day you conceived, do you mean you know the day you ovulated or the day you had sex?

We know when both took place. Since I had my first my cycle has been very average and predictable.

So if you know the day you ovulated, just tell your doctor what day you ovulated. But honestly, it doesn't really matter. Because they can tell how far along you are when they measure the baby. When I had my first ultrasound, the ultrasound tech assumed I was seven weeks along based on my LMP, and I knew I was 6 weeks 5 days. She measured the baby, and it measured at 6 weeks 5 days. Voila. They knew how far along I was.

Ivana_Stolichnaya · July 2011

If you know your LMP then just give them that.

mommybrynn · July 2011

I am going by my LMP, although I have a 26 day cycle so I don't know if that makes it different... but either way at the ultrasound, my date and theirs was only 2 days off, so I didn't bother changing my ticker or anything. I had DD a week early, I am thinking this one may follow suit if my doctor is correct in her feeling that most Moms tend to repeat their histories.

mca21 · July 2011

I thought I was much farther ahead than I was - due to my longer cycles and a small period - they measured the baby on the ultrasound to give me an actual date - I thought Feb 4 - they have changed it to Feb 20.

hillbillysunshine · July 2011

Your EDD is give or take anyway. Meaning, you're full term at 37... anything after that is - technically - fine. And most won't consider inducing until you're a week or so after your due date (unless you have a doc that pushes that kind of thing or you have medical reasons to do so earlier). So an EDD is just that: an estimate. I really don't think it's that big of a deal.

lindsayandjamie · July 2011

I was charting and know exactly when I ovulated (on CD86) so I provided my m/w with my ovulation date. I pushed for a dating ultrasound just to be sure, and I'm hoping it will be confirmed next week. If I wasn't charting, they would have required one anyways since my LMP was March 6.

LilyPotter218 · July 2011

My LMP has me due March 20th and O date has me due March 28th. (O'd on CD23). My ticker is set to my O date, but when I told my parents I just averaged the two as to how far along I was... Not scientific, but it is only 8 days.

According to LMP I am 6w0d, according to O I am 4w6d = 5ish weeks in my head

hilwithonelary · July 2011

I calculated mine from my O date, which was CD 20. I lied about my LMP when I made my appointment so that the EDD they calculated would match mine. I know that a lot of people say "it's just an estimate anyway, so it doesn't really matter," but I disagree. I have no expectation that my baby will come on his/her due date, but I don't want to be pushed for induction earlier than necessary. I know a lot of women are pushed for induction at 41 weeks. I'm personally comfortable waiting until 42 weeks. When you get down to the end, a few days of waiting can mean the difference between being induced or going into labor spontaneously. I want to make sure I am given as much time as possible prior to being induced.

ETA: And even with early ultrasound, I would rather go by O date. With DS, I ovulated on CD48. Stupid me told my OB my LMP, but tried to insist that I O'd late. My OB didn't believe me, but then said my uterus was measuring small during an exam. She did a dating ultrasound, but by then I was already 10w. She measured me at 10w6d. I ended up going early with DS. I was 37w3d by ultrasound, 36w4d by ovulation. Guess what? At birth, DS was evaluated to be 36.5 weeks. He was then treated as a near term premie for the rest of our stay. If they had believed me to start with, they would have known that he might have possible near term complications prior to delivering/evaluating him. He had some minor breathing issues, but ended up fine. Those last few weeks can make a huge difference in development. I want to make sure my birth team knows exactly how far along I am so they can take any appropriate precautions.

Cranang · July 2011

You're going to give the doctor the date you supposedly conceived as the date of your LMP? That makes no sense.

FAIL.

salt78 · July 2011

The doctors office went by my LMP date at first even though I told them when I ovulated (I was charting) and knew that would be wrong. So when I went in for my first u/s at what they thought was over 8 weeks, it was no surprise to me that I only measured 6w3d.

SRodi811 · July 2011

I didn't O until CD 27 (I took OPK's)... so I told my doctor that and we are going off of that date instead of my LMP date. We will double check my due date when we have our u/s next week.

KaliChick · July 2011

The date they took my eggs out of my ovaries and fertilized them in a dish. My LMP has nothing to do with it and since I didn't ovulate that's not a factor either.

In fact, I was told my due date will.not.ever change because we know the exact dates of everything. Not that the baby will come that day, just the day s/he is due.

diana.filipi · July 2011

We did IVF so I know the EXACT time of conception. They did ICSI so each egg was actually injected with a sperm. No question that I conceived on June 13th. I use that date and add two weeks to the rear of it to attain my LMP date. That's the way my OB calculated it as well; he added two weeks back onto June 13th.

Also, what a couple pps have said really is the truth. Your EDD isn't so important that days matter. For instance, we did IVF with the last pregnancy as well. I gave birth at 42w1d!

How are you calculating your due date?

Re: How are you calculating your due date?

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