In the survey, 35 participants claim to know their exact conception date. This is rare; most due dates are measured from last menstrual period because it's easier to track. But the general question that always comes up is "Would my due date be more accurate if based off the conception date?"
On the main probability chart I found that due dates have about an 8-10 day standard deviation, meaning that the bulk of the babies are dispersed within plus or minus 10 days of their due date.
For this graph, I subtracted each babies birth date from his or her conception date, then added 14 days across the board because that's usually what we do when calculating a due date based on conception.
The standard deviation didn't improve much when compared to all the women in the survey. So bad news... even if you know the second your baby was conceived, your due date won't be any more accurate.
There is a related chart that compares LMP due dates with ultrasound-determined due dates. It also found no noticable difference in standard deviation.
The statistics right now are as follows:
|Day||Week||Births||Running Total||Percent||Running Total %|
|245||35W,0D||0||0||0 %||0 %|
|246||35W,1D||0||0||0 %||0 %|
|247||35W,2D||0||0||0 %||0 %|
|248||35W,3D||0||0||0 %||0 %|
|249||35W,4D||0||0||0 %||0 %|
|250||35W,5D||0||0||0 %||0 %|
|251||35W,6D||0||0||0 %||0 %|
|252||36W,0D||0||0||0 %||0 %|
|253||36W,1D||0||0||0 %||0 %|
|254||36W,2D||0||0||0 %||0 %|
|255||36W,3D||0||0||0 %||0 %|
|256||36W,4D||0||0||0 %||0 %|
|257||36W,5D||0||0||0 %||0 %|
|258||36W,6D||1||1||2.9 %||2.9 %|
|259||37W,0D||0||1||0 %||2.9 %|
|260||37W,1D||1||2||2.9 %||5.7 %|
|261||37W,2D||0||2||0 %||5.7 %|
|262||37W,3D||1||3||2.9 %||8.6 %|
|263||37W,4D||0||3||0 %||8.6 %|
|264||37W,5D||0||3||0 %||8.6 %|
|265||37W,6D||1||4||2.9 %||11.4 %|
|266||38W,0D||0||4||0 %||11.4 %|
|267||38W,1D||0||4||0 %||11.4 %|
|268||38W,2D||2||6||5.7 %||17.1 %|
|269||38W,3D||0||6||0 %||17.1 %|
|270||38W,4D||1||7||2.9 %||20 %|
|271||38W,5D||1||8||2.9 %||22.9 %|
|272||38W,6D||2||10||5.7 %||28.6 %|
|273||39W,0D||0||10||0 %||28.6 %|
|274||39W,1D||0||10||0 %||28.6 %|
|275||39W,2D||0||10||0 %||28.6 %|
|276||39W,3D||2||12||5.7 %||34.3 %|
|277||39W,4D||1||13||2.9 %||37.1 %|
|278||39W,5D||5||18||14.3 %||51.4 %|
|279||39W,6D||0||18||0 %||51.4 %|
|280||40W,0D||0||18||0 %||51.4 %|
|281||40W,1D||1||19||2.9 %||54.3 %|
|282||40W,2D||1||20||2.9 %||57.1 %|
|283||40W,3D||3||23||8.6 %||65.7 %|
|284||40W,4D||1||24||2.9 %||68.6 %|
|285||40W,5D||0||24||0 %||68.6 %|
|286||40W,6D||1||25||2.9 %||71.4 %|
|287||41W,0D||3||28||8.6 %||80 %|
|288||41W,1D||2||30||5.7 %||85.7 %|
|289||41W,2D||2||32||5.7 %||91.4 %|
|290||41W,3D||0||32||0 %||91.4 %|
|291||41W,4D||0||32||0 %||91.4 %|
|292||41W,5D||0||32||0 %||91.4 %|
|293||41W,6D||1||33||2.9 %||94.3 %|
|294||42W,0D||1||34||2.9 %||97.1 %|
|295||42W,1D||1||35||2.9 %||100 %|
|296||42W,2D||0||35||0 %||100 %|
|297||42W,3D||0||35||0 %||100 %|
|298||42W,4D||0||35||0 %||100 %|
|299||42W,5D||0||35||0 %||100 %|
|300||42W,6D||0||35||0 %||100 %|
Due Date Survey DataDue date statistics: A study on the length of pregnancy
Probability of delivery resulting from spontaneous labor after 35 weeks
Probability of delivery within x days of a given date
Length of pregnancy by week
Spontaneous labor and due date determination
Length of pregnancy, comparing subsequent births for individual moms
Length of pregnancy for first time vs. second & third time moms
Length of pregnancy, type of delivery
Gestation vs. Birthweight
Probablity of Induction after a given day
Average day of spontaneous labor vs. age of mother at time of birth
Are more babies born during a full moon?
What's the most common day of the week for babies to be born?
I'm still pregnant at 40W. What's it mean?
Do winter babies arrive later?
What if I know my conception date?
Are boys or girls born later?
Subsequent pregnancy date search
How do inductions bias the due date statistics?
Download the data
Survey input dates
More ResourcesPregnancy Day-by-Day
Fast pregnancy calendar
Baby age calendar
EDD Icon Generator
Jo's Birth Story
Weeks vs. Months Explained
Charts generated by flot
but I take them to restaurants so I know they end up hating 90% of the things they ask for.
- kid would like a sibling
- maybe people are right about end of life stuff
That's about it. I hated being pregnant, the last time I was pregnant the hormones were... really awful. Plus kid is now pretty big so another one would be weird and we gave away all our stuff.
I can still highly recommend this book: (
Also, keep speaking English! Toddlers forget fast when a language is no longer present.
Things you don't need:
Anything soft, fluffy or furry. My baby couldn't care less about minky blankets and soft toys. Plus they seem more gross to clean when they get covered in bodily fluids.
Clothes that look like adult clothes. It's so difficult to squeeze baby thighs into miniature corduroys or denim jeans which have no give to the fabric.
Baby washcloths. Babies make a disproportionate amount of mess so you need adult size washcloths to clean them up.
Things that were super useful:
A folding changing mat. I have a SkipHop one which has enough storage for wipes and diapers, which was all I needed to carry with me when I had a newborn. Now that he's bigger, I appreciate the larger size of the mat because the one that came with my diaper bag is way too small.
Balls. They were the first thing he played with and still his favourite toys. At the beginning he liked one made by Oball which was easy to pick up, and a soft fabric one which made a crinkly noise. Now he loves throwing a soft rubber ball and watching it bounce.
Somehow MIL has still given us a ton of pink clothing that she'll change him into everytime she comes over.
I hate pink.
I had an appointment with the obgyn today. He seems to think I'm even farther along than he originally thought. I didn't have an ultrasound. He just went by the size of my uterus. It's well over my belly button now. He's sending me to a high risk Dr. Asap and then I'm suppost to see him again on the 29th. By then he said they will have a better idea as to how far along I actually am. So far the pregnancy is going well. I did have complications with my first one and went to a specialist but this time I'm being referred to one because I'm old lol. They automatically send women when they are 35 and older.
Not having read your post, but just the heading, my response was "wine." But after reading your post, I thought "wine."
Yes. After bedtime.
Also, honestly the only way we made it through was we would take turns being the center of focus. We still do this, divide and conquer (and she's only one kid, hell). Also, I know people are like really limit screen time BUT if you really need to get something done one episode of e.g. Daniel Tiger or Paw Patrol or whatever isn't gonna be too bad. I think DarkOne has some good ideas too.
Also I know you can do wills and stuff on your own but honestly I found it super useful to talk through it with a lawyer who does that. She thought of things we never would have. (hm really should revisit now that kid is older) It was a one time fee and not that bad.
We do most of our banking through a credit union. Have been happy with them. We refinanced our mortgage through them when we did that. I remember the big credit union bust ages ago, but there are lots more protections in place now and big banks can be pretty awful.
Today for the first time my 11month old showed interest in a stuffed animal. Just before Christmas we received a box from Amazon with a giant bear inside. No gift wrap, no note. Just a bear the size of my child. It's been sat in his room and ignored completely, despite him exploring literally everything else that is in there. Then, out of the blue, he made a beeline for it and tried to pull its eyes out.
But if generally tactile surfaces also apply, mermaid sequin pillows are comforting. It was one of my impulse buys at a department store about a month ago. I couldn't stop petting the display. The sequined side seemed like it wouldn't be comfortable to rest on but it hasn't been an issue. My stepdad really likes them so I got him one for giftmas and he said it helps distract him when chronic pain keeps him awake at night.
I haven't field tested them on my nieces and nephews yet. That could be fun.