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 7287 responses. 5483 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,0D92921.3 % 1.3 %
26738W,1D901821.2 % 2.5 %
26838W,2D872691.2 % 3.7 %
26938W,3D1223911.7 % 5.4 %
27038W,4D1545452.1 % 7.5 %
27138W,5D1406851.9 % 9.4 %
27238W,6D1708552.3 % 11.7 %
27339W,0D19010452.6 % 14.3 %
27439W,1D17412192.4 % 16.7 %
27539W,2D18314022.5 % 19.2 %
27639W,3D23416363.2 % 22.5 %
27739W,4D25518913.5 % 26 %
27839W,5D25821493.5 % 29.5 %
27939W,6D29724464.1 % 33.6 %
28040W,0D31127574.3 % 37.8 %
28140W,1D30430614.2 % 42 %
28240W,2D27733383.8 % 45.8 %
28340W,3D26936073.7 % 49.5 %
28440W,4D24338503.3 % 52.8 %
28540W,5D25541053.5 % 56.3 %
28640W,6D25243573.5 % 59.8 %
28741W,0D25746143.5 % 63.3 %
28841W,1D17647902.4 % 65.7 %
28941W,2D14749372 % 67.8 %
29041W,3D15150882.1 % 69.8 %
29141W,4D11151991.5 % 71.3 %
29241W,5D8252811.1 % 72.5 %
29341W,6D6753480.9 % 73.4 %
29442W,0D5554030.8 % 74.1 %
29542W,1D2154240.3 % 74.4 %
29642W,2D2154450.3 % 74.7 %
29742W,3D1254570.2 % 74.9 %
29842W,4D954660.1 % 75 %
29942W,5D654720.1 % 75.1 %
30042W,6D254740 % 75.1 %
30143W,0D954830.1 % 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.

Interacting with parents whose choices you don't trust

Thu Mar 26 3:08 PM by rowan in Pregnancy & Parenting

How can you tell who has been vaccinated or not?
That's the tricky part, you can't really. So unless the parents say something you never actually know.

Bilingual Babies

Sun Mar 22 9:23 PM by Isabella357 in Pregnancy & Parenting

My spouse and I speak Spanish exclusively in the house and since our kids our 3 kids aren't in school yet, you'd think they'd speak and understand only Spanish. Ha! After overhearing phone conversations, grocery store interactions, work negotiations, and watching YouTube, our kids speak primarily English. They still understand Spanish, but they usually respond in English. We make a point to use Spanish words for everything (especially emotions) because many of our family members don't speak any English. While being bilingual may not make the kids smarter or more successful, it will help them to build stronger and more meaningful relationships with members of their family like aunts and grandmothers.

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.

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."


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

Tips and pitfalls for gender-neutral parenting

Thu Mar 26 10:17 AM by Nae in Pregnancy & Parenting

I'm a while off having kids, but everything is so pervasively gendered I've had these concerns too.

Kids will learn a lot from what their parents do rather than say, so the most important thing you can do is just to be a good parent who believes in equality.

Media will be yelling at them their whole lives that they should conform and buy their products etc., so a healthy dose of cynicism could be learnt to.

You could try bringing it up with your kids to challenge them; "But why does he say that toy isn't for boys?".

It takes 13 million calories to raise a child!

Sun Mar 15 6:33 PM by Metcodon1 in Pregnancy & Parenting

Child care is BEYOND insanely expensive... When my husband and I were deciding to to have children we agreed to both go part time (4 days a week) in order to make our lives easier (we both make more than we would pay for day care, so we did take a financial hit with this decision). For example, whoever is home on a given day can throw in some laundry, or some food into the slow cooker, run errands... All of these things multiply in number once you have kids at the same time becoming more difficult to schedule. Unfortunately, when my daughter was around 1 my work situation changed and I had to go full time... let me tell you, it was definitely easier when I wasn't.

Anyway, the point I am getting to here is, when kids are little they require a lot of attention and sometimes (often?) some career sacrifice but it's TEMPORARY. When we decided to get pregnant we agreed that we would both slow down career wise for 5 years. For us it means, we do our jobs, we come home. We don't sign up for extra projects, we try to limit our travel, but it's all just for now. We also decided to have our kids close together for that reason (they'll be 2 years apart). Anyway, it's something to keep in mind. An 8 year old goes to school and doesn't need constant monitoring to keep from killing him/herself. It's ok to decide to slow down for a period of time, knowing that you'll come roaring back once they're older.


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.

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:

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

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.

How Good Parents Miss Child Sexual Abuse and 5 Questions to Change That

Tue Mar 24 3:20 AM by rowan in Pregnancy & Parenting

And that includes parents too - I try to always ask "can I have a hug/kiss" rather than "give me a hug/kiss" and that she can always always say no if she doesn't want to, even with me. (She's old enough now that I've had enough practice that even writing "give me a hug" sounds weird to me)

Also I think on a more general level it's good to practice asking these kinds of questions anyway. Not just for abuse, but in general if you want to know what's going on in their life. Asking "how was school" gets an "I dunno" even now, but asking more specific things like "What was something funny that happened today" or "What did you do at recess?" really gets her talking more. Not sure where I read that, but the kinds of questions above made me think that sometimes just asking a better question will help get at what you want to know more than asking generalities.

The other thing is definitely definitely not making judgment on those things that they're saying. Instead try "What did you think about that ?" or "What did you do when happened?" "What would make you feel safe?" "What could you try if that happens again?" "Is there anything you'd like me to do?" These are things that I've asked wrt other kids on the playground (pushing etc) but I think it's the same idea in terms of empowering the child to talk about things that happen and letting them help come to the conclusions. Which isn't to say you can't help them get there by suggesting actions they could do, etc, just that if you get them talking about things that happen on a daily basis then if something weird happens then they'll likely be more comfortable telling you, especially if you've already shown them what boundaries there are and respecting those boundaries (like not tickling if they say they don't want to be tickled etc).

Breastfeeding & accoutrements thereof

Thu Mar 12 8:27 PM by Rgipson in Pregnancy & Parenting

It's okay to admit your happiness is worth more than the "good" that solely breastfeeding supplies.

I breastfed my first until 10 months. I fed/pumped thru many growth spurts or dips in supply. Who knows, right? Baby would cry and cry and I could tell there was no milk, but I persevered. The trickiest part was, she wouldn't nurse in a room where she could look around or hear sounds (I'm a SAHM), so I had to go in a dark room, turn the lights off, and use a white noise machine. EVERY TIME SHE FED FOR 10 MONTHS. Talk about being hamstrung. I tried on so many occasions to feed her in other places, only to have a baby scream, scream, scream, until we got back to the dark room.

I was sleep deprived, overstimulated from all that screaming (she had colic until 14 months), and I was depressed as all get out. When I finally stopped, I began to feel like myself again. I believe that just as some women feel euphoria from the let down - that glorious oxytocin rush - it negatively effected my brain chemistry. It contributed to a negative mental health spiral.

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.

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:" ... babybooks/

some quotes recently I read

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

i search about these quotes in google