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Probability of delivery within x days of a given date

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This graph shows only babies born as a result of spontaneous (non-induced) labor (75% of all participants).

Do babies come on their due dates? Not really. But they seem to come around their due dates. In the survey, only 308 out of 8034 (3.8%) spontaneously arrived on the exact day. But if you look around that date, the numbers get bigger fast... 1944 babies (24.2%) arrived spontaneously between 39 weeks 4 days and 40 weeks 3 days. 3702 (46.1%) arrived spontaneously within a week of their due date. Throwing out inductions makes those percentages even higher: 61.1% of all non-induced babies arrived within a week of their due date.

I also think this graph is important because it shows how meaningless it is to move a due date one or two days. For example I have a chart comparing first time moms to mothers who've had previous births, and it shows about a 1-2 day difference. But based on this graph, who cares about a day?

What I mean is this: a woman who's not induced has a 61.1% chance of giving birth within a week of her due date. Let's say we lie to her and tell her a date that's three days early. Now she has a 59.8% chance of delivering within a week of that "wrong" date. It's not really a huge difference.

Data Table

DayIn weeksBabies Spontaneously Born
24535W,0D10
24635W,1D15
24735W,2D9
24835W,3D19
24935W,4D11
25035W,5D13
25135W,6D13
25236W,0D24
25336W,1D19
25436W,2D26
25536W,3D31
25636W,4D24
25736W,5D30
25836W,6D29
25937W,0D41
26037W,1D43
26137W,2D40
26237W,3D64
26337W,4D68
26437W,5D56
26537W,6D90
26638W,0D88
26738W,1D89
26838W,2D84
26938W,3D122
27038W,4D151
27138W,5D137
27238W,6D168
27339W,0D188
27439W,1D173
27539W,2D179
27639W,3D230
27739W,4D250
27839W,5D252
27939W,6D294
28040W,0D308
28140W,1D301
28240W,2D272
28340W,3D267
28440W,4D239
28540W,5D249
28640W,6D249
28741W,0D251
28841W,1D171
28941W,2D144
29041W,3D145
29141W,4D106
29241W,5D81
29341W,6D65
29442W,0D52
29542W,1D20
29642W,2D21
29742W,3D12
29842W,4D9
29942W,5D6
30042W,6D2
30143W,0D9

Due Date Survey Data

Due 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?
Birth Stories
Survey input dates

More Resources

Pregnancy Day-by-Day
Fast pregnancy calendar
Baby age calendar
EDD Icon Generator
Jo's Birth Story
Weeks vs. Months Explained
Charts generated by flot
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Recent Comments

For more support, encouragement, Q&A,
you are invited to join our pregnancy forum. We are dedicated to answering complicated questions as logically as we possibly can.

Bilingual Babies

Mon Mar 2 7:38 PM by Nachos in Pregnancy & Parenting

I am/was a bilingual kid. I am now a bilingual (in another language though) adult. My mother is Dutch and I was born in England so I grew up speaking and understanding English and Dutch. I don't believe I had any problems up until my first day at school when apparently I came home saying "I don't want to speak that funny language any more!" and since my mother was told my doctors and teachers to only speak one language to your kid, I ended up forgetting it all.

Later on (when I was 11) we ended up moving to a Dutch speaking country and even though I was immersed in school I had to learn it all over again. Funnily enough, after about 7 months something clicked and the language started to come back.

Next problem was then we moved to Germany and even though the languages are similar, they are not the same. It took me about three years (immersed again) while learning German too for something to click and I started to also dream in German.

My Dutch teacher in the Dutch country had a grandson who spoke 4 languages fluently at the age of 6. He could differentiate between them too.


Breastfeeding & accoutrements thereof

Thu Feb 26 5:28 PM by rowan in Pregnancy & Parenting

My boobs are small, and this is important for a couple of reasons: At any one time I can only produce a max of about 6 oz.
Actually, the physical size of your boobs doesn't have much to do with how much you produce. There are lots of small-breasted women who produce a lot and lots of large-breasted women who don't. It's mostly genetic and some other variables thrown in (e.g. if there was a lot of BPA in your mom when you were in utero can affect it, we're finding out).


Keeping your pre-pregnancy/parenthood identity

Thu Jan 29 4:36 PM by rowan in Pregnancy & Parenting

You don't have to post at all if you don't want to! But we're here to offer support if you do want to.

I have very little time sans baby anymore
This does get a little better over time, when they're a little more autonomous. Though I still long for the day when I can just freaking go to the bathroom all by myself. (I seriously spent like 20 minutes in the bathroom the other day while the hubby was watching the kid @ a birthday party, just for that reason. I mean how sad does that sound?)

I know he requires more alone time than I do, and I know he isn't getting any more than I am.
Any chance of arranging a tag-team schedule?


sleep humor

Fri Jan 23 7:13 PM by rowan in Pregnancy & Parenting

Here's a really funny humor bit about sleep, but the same general idea can apply to pretty much any "advice" given to new parents.

"I bought all the top books on baby sleep and development. I read through them all, as well as several blogs and sleep websites. I gathered lots of advice:"

https://chimericalcapuchin.wordpress.co ... babybooks/


Why Pocket Diapers Are Better Than Disposables

Sun Jan 11 3:31 PM by Nancy Erick in Pregnancy & Parenting

Hi everyone

A Beautiful article by writer Kathryn McDowell recently I read liked to share with you

Why Pocket Diapers Are Better Than Disposables :


As a young parent, you've no doubt heard of pocket diapers. Perhaps a neighbor or a co-worker told you about them. Or it was your babysitter, who asked you to get them soon. Well, so many families in America are today turning to pocket diapers for their little ones. But a majority still holds on to disposable diapers, while being curious about pocket diapers at the same time.

Why are diapers so great? For a start, pocket diapers come with brand new fabrics and super absorbent pads, are easy to put on, simple to take off, easy to wash and quick to dry. And they are better than disposable diapers.

They are Cheaper
Until your child is potty trained, you'd probably spend something close to $2500 to $3000 on diapers - which is quite a lot. Biodegradable disposable diapers are even costlier. But with pocket ones, you won't have to spend anything more than $350 to $400, till your child is potty trained.


10 things you can leave off the baby registry

Sat Feb 28 7:48 AM by Gnarlbanya in Pregnancy & Parenting

I really want one of those baby boxes and would jump at it if not for $69.95 shipping. Will keep thinking about it, I suspect my resolve will crumble eventually.


Bonding

Fri Feb 6 4:35 AM by Zeph in Pregnancy & Parenting

Bonding with my future infant is a concern of mine, because my depression is debilitating. I'm relieved to know that normally functioning women don't feel that head-over-heels mushy baby love.


name trends

Wed Jan 28 8:58 AM by Lemon in Pregnancy & Parenting

Some of my family members who work in the healthcare system have overheard some doozies.

I work in healthcare, so I can relate. I think my favourite was a kid called "Abcde" which we were assured was pronounced "Abasidee". Mirena was a cute choice, named after the contraceptive device. Then there have been some good narrative names including places of birth - e.g. "Shell" (after the baby born in a petrol station carpark) - and places of conception - e.g. "...(a suburb which I'll keep secret - just in case this somehow breaches some poor kid's privacy) bus stop."


It takes 13 million calories to raise a child!

Wed Jan 21 4:32 AM by textualorientation in Pregnancy & Parenting

Recently found out how much energy it takes to raise a child. Woah.

I'm pretty infuriated that in Canada it can cost $1,676/month for daycare, when science actually tells us we evolved to help each other raise children. I wrote a blog about this in case anyone is interested! I would really like to see this change for mothers all over Canada.

https://textualorientation.wordpress.co ... ledaycare/


some quotes recently I read

Sat Jan 10 4:50 PM by Nancy Erick in Pregnancy & Parenting

i search about these quotes in google


How did you decide how many kids to have?

Fri Feb 27 2:42 AM by MFS in Pregnancy & Parenting

First 2 were on purpose, 3rd kinda not so much, 4th was totally an oops (when you think things are broken, they have this habit of fixing themselves). Made sure we were done after that. Aside from that, we knew we'd have at least 2, likely 3, but the timing was not at all what we thought we were "planning". Such is life.


Because judging other parents is absurd.

Tue Feb 3 7:05 AM by Zeph in Pregnancy & Parenting

It's alright to discuss these topics, but there needs to be boundaries. I would use the following, personally:

1. Don't insert yourself into a stranger's situation or bring up the topic yourself to a stranger.
2. It's probably not your business if you're not a parent yourself.
3. Ask the person why they are making these choices, don't assume.
4. Try to end on a positive note.

I don't feel right bringing up to my sister that I don't agree that she spanks my nephew, but after being a teacher, I am pretty forgiving of parents' choices. It's the hardest role there is. Even though I want to raise my children on nutritious meals, cloth diapers, and museum passes, I know I'm going to slip up and give them fries, Huggies, and Disney DVD's.

I also feel that home birth is a fine option for low-risk births, where the mother is well coached and the midwife is reputable. If you live near a hospital and your midwife is highly qualified, why not? They have equipment. I won't be choosing this option, but with any birth plan there needs to be a series of precautions taken.


34 Weeks

Fri Jan 23 11:57 PM by Sonic# in Pregnancy & Parenting

Probably not. As we pointed out in the other topic, 34 weeks isn't even on the chart because it's so rare:
http://spacefem.com/pregnant/charts/duedate1.php

You'd be better off worrying over a car accident.


Work

Thu Jan 15 9:17 PM by bigdaddy in Pregnancy & Parenting

I will do cheers but in people's experiences and options I should be ok


Working as due date approaches

Mon Jan 5 6:18 AM by Bork in Pregnancy & Parenting

However long you end up staying at work, once you're in labor, PLEASE GO HOME. Or to the hospital. Because staying at work while you're in labor is hella awkward for everyone involved.