Due Date Affected by Cycle Length?

Our office give a 2 week window instead of a specific date... it's because even if you know the exact date of conception implantation and maturation can happen differently. Some babies are physically mature at 38 weeks, others not until 42 weeks. But take that 38 week baby and wait a month... bad juju. Ditto the 42 weeker and pull a month early. In addition to the baby's physical maturity, when the "toaster bings" is different for everyone.

Because of my irregular cycle I got a solid MONTH as my duedate (mid june to mid july). So much fun. I felt like the old Mervin's commercial "Open, open, open, open" or kids in the back seat "Are we there yet? Are we there yet?"

My own son was born dead center at the halfway mark, but he was probably a 42 week baby. Was born with full control of his head and neck, eye contact, etc.

I had the opposite. LOL
I have Long cycles when I am not using hormones. But not an exact number of days either... it ranged from 29 - 43 days per cycle. My firstborn was 12 days past his due date, but I don't think that necessarily means that his due date "should" have been later... he was big and mature. :)

Same deal with daughter, only she was 7 days "early"... she was an average size baby. 7 lbs 6 oz. 20 1/4 in.

I would think, though, that if you routinely have 21 day cycles, that you would ovulate a few days earlier than someone with a "normal" 28 day cycle. So implantation, etc would happen a few days earlier than if calculated on a 28 day cycle.
Here's my question... do you know the dates (around that time) that you 'took advantage of the opportunities" baby making? If you do, that might be helpful too. LOL

Either way, I don't think it will be a big deal with regard to due date and actual delivery--unless you end up looking at induction for some reason. THEN you need to be very cautious.
Good luck.
And congratulations!

I had this problem too. I had no idea when my LMP was when I got pregnant, so the doc didn't even have anything to calculate my due date with until the ultrasound. He said that was really the best way to tell anyway.

So, I would go with the ultrasound.

Every woman is different; every pregnancy is different.

Yes, your due date could be affected, but I wouldn't worry about it. Most doctors are induction-happy anyway, so babies are often born (artificially) too early, and then have problems adjusting. Not every apple on the tree ripens at exactly the same time; some go faster and others slower.

A "due date" is an estimation, and [as Laura Ingalls Wilder said about ambition] is "a good servant, but a bad master." It may give you a statistical norm, or a date that may be a good thing to keep in mind so that you'll know if your baby is way early or way late, but it is *just* an ESTIMATED due date, and is most certainly not set in stone!

There have been babies born "early" (according to their due dates) who were actually term; and there have been, sadly, many more babies born on or near their due dates who were actually preterm and had problems adjusting to life on the outside (spent time in the NICU, had breathing problems, etc.) because they were actually premature.

Think, "By Thanksgiving my baby will be here," and then if it's late, you won't be so anxious. But you can work on having everything prepared by early October so if your baby is born a few weeks before your Halloween "guess date", then you'll still be ready. And, really, that's what all women have to do anyway. "Term" is from 37-42 weeks of gestation, so we *all* have a 5-week "window" of when birth may happen.

P.s., Go with the later date - it will save you the hassle of being induced too soon for going "too far past your due date" if you don't have the baby by Nov. 7. And if you have the baby 3 weeks before that date, then it's still term.

Your overall cycle isn't nearly as important as when you actually ovulate (which could be either earlier or later in your cycle than, say, an average of day 14 for a 28-day cycle.)

Either way, this is the reason that due dates are bunk, and why it's perfectly normal to go into labor anywhere from roughly 38 to 42 weeks. You could still have a mid-October baby or mid-November baby regardless of what the calendars and ultrasounds say.

I also have shorter cycles. My first was born a week before my due date (my Dr. had already upped my due date 3 times) my second I was induced three weeks early, so not sure on that one. My third my Dr. has given me a due date of 7/10 and websites say 7/5. We'll see in a couple of months what happens!! Congrats to you!!