Probability of delivery resulting from spontaneous labor after 38 weeks

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The most important question I was trying to answer with the survey was this: "When is a baby most likely to spontaneously show up?" The graph above shows the percentages, based on 7033 responses. 5288 of the deliveries were as a result of labor occuring spontaneously. The chart only shows these deliveries, which is why the percentages do not add up to 100%, because only 75% of participants had spontaneous (non-induced) labor.

This page shows what day you'll likely give birth, if you're still pregnant at 38 weeks. To find out how week 38 compares to the other weeks overall or to find out the probability of delivery at 38 weeks, refer to the Length of pregnancy by week chart.

The statistics right now are as follows:

Data Table

The percentages are based on ALL births (including inductions)
DayWeekBirths Running TotalPercentRunning Total %
26638W,0D87871.2 % 1.2 %
26738W,1D881751.3 % 2.5 %
26838W,2D832581.2 % 3.7 %
26938W,3D1213791.7 % 5.4 %
27038W,4D1495282.1 % 7.5 %
27138W,5D1366641.9 % 9.4 %
27238W,6D1618252.3 % 11.7 %
27339W,0D18310082.6 % 14.3 %
27439W,1D16911772.4 % 16.7 %
27539W,2D17713542.5 % 19.3 %
27639W,3D22915833.3 % 22.5 %
27739W,4D24518283.5 % 26 %
27839W,5D24720753.5 % 29.5 %
27939W,6D28723624.1 % 33.6 %
28040W,0D30926714.4 % 38 %
28140W,1D29829694.2 % 42.2 %
28240W,2D26632353.8 % 46 %
28340W,3D25734923.7 % 49.7 %
28440W,4D23337253.3 % 53 %
28540W,5D24439693.5 % 56.4 %
28640W,6D23842073.4 % 59.8 %
28741W,0D24944563.5 % 63.4 %
28841W,1D16946252.4 % 65.8 %
28941W,2D14247672 % 67.8 %
29041W,3D14249092 % 69.8 %
29141W,4D10450131.5 % 71.3 %
29241W,5D8150941.2 % 72.4 %
29341W,6D6551590.9 % 73.4 %
29442W,0D5152100.7 % 74.1 %
29542W,1D2052300.3 % 74.4 %
29642W,2D2152510.3 % 74.7 %
29742W,3D1152620.2 % 74.8 %
29842W,4D952710.1 % 74.9 %
29942W,5D652770.1 % 75 %
30042W,6D252790 % 75.1 %
30143W,0D952880.1 % 75.2 %

Due Date Survey Data

Due date statistics: A study on the length of pregnancy
Probability of delivery resulting from spontaneous labor after 38 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

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.

Because judging other parents is absurd.

Sat Jan 24 8:54 PM by ladyhawk in Pregnancy & Parenting

No, there's a whole shitton of judging that is not helpful nor useful or even worth debating and just makes you feel like shit when your hormones are already fucked up and you are really trying to do your best.

This. Times a million.

name trends

Thu Jan 22 1:42 AM by Nedra in Pregnancy & Parenting

I am also surprised at the decline of F-names-- I actually thought they were "Hot" right now, but I guess not yet. I like Florence and Frances, which I know are "old-lady" names, but they seem so ripe for a comeback.

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Mon Jan 19 6:33 AM by Ashenskisla in Pregnancy & Parenting

I have been breastfeeding for the past 10 1/2 years, 1st and 2nd kids until 5 years ish, and currently have a 2 month old. For me it's been very easy.
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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
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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.

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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:

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

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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. ... ledaycare/


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

some quotes recently I read

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

i search about these quotes in google

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Fri Jan 2 1:27 PM by spacefem in Pregnancy & Parenting

Good topic.

Ya know, I think the one thing I remember is that it wasn't as big a deal as I thought it was. When I was pregnant I'd look at my three year old and think, "What can we do for this delicate little child whose world is about to be upside-down?" Then the baby came home, the three year old suddenly looked like a teenager to me, and I was like eh go fend for yourself kid. And honestly, she did great. She's still really sweet to her little sister.

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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:" ... babybooks/

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Mon Jan 19 4:17 PM by Metcodon1 in Pregnancy & Parenting

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