Probablity of Induction after a given day

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Induction odds by day

Here's the big question this graph is trying to answer:

The western world likes to induce babies rather than let them go too late, doesn't this skew your results by removing late babies from the "late" end of the spectrum where they should be?

I don't think so. This survey contained 3583 births resulting from inductions (out of 15099 total). Only 8% (271) of the inductions were at or past 42 weeks, 0 D. By that time, 96.7% of all spontenous labors have already happened. At 41 weeks 0 days, 11813/15099 (78.2%) of spontaneous labors had already happened. But only 1224 inductions happened after that date.

There's a study that suggests the average first time mom goes into labor 8 days past her due date. Even though the study is 20 years old, the notion of moving everyone's due date to 41W1D has not caught on. Why not?

The survey results show that there were 8104 spontaneous labors before 41 weeks and 3412 spontaneous labors after 41 weeks. If all 1224 inductions were added to that "spontaneous" count, that'd mean there were 4636 babies born after 41 weeks... not enough to tip the scales. What if all the inductions after 40 weeks (2084) were actually supposed to be spontaneous labors after 41 weeks? That'd mean 5496 babies would be born after 41 weeks. Remember, we'd need at least 8104 to happen spontaneously after 41 weeks to match the ones that spontaneously happened before 41 weeks; a median means that half happen before, half after. It'd be tough for the median to move a whole 7 or 8 days. It all tells me that reducing inductions will not shift the median to the right a whole lot.

I've also added a table here that shows how the median would shift if ALL inductions, not just the later ones, were actually supposed to be "late" births.

Does the data change for first time mothers?

I've received a lot of questions about whether these statistics shift for first time mothers. You can click here to exclude all non first-time moms

Induction odds by day

DayTotal pregnancies remainingHow many will end in induction
#% #%
245 15099 100 3583 23.7
246 15068 99.8 3575 23.7
247 15043 99.6 3572 23.7
248 15019 99.5 3569 23.8
249 14984 99.2 3559 23.8
250 14947 99 3546 23.7
251 14911 98.8 3537 23.7
252 14885 98.6 3535 23.7
253 14819 98.1 3514 23.7
254 14776 97.9 3501 23.7
255 14719 97.5 3488 23.7
256 14665 97.1 3481 23.7
257 14617 96.8 3470 23.7
258 14557 96.4 3457 23.7
259 14478 95.9 3438 23.7
260 14347 95 3395 23.7
261 14238 94.3 3366 23.6
262 14126 93.6 3336 23.6
263 14007 92.8 3312 23.6
264 13870 91.9 3289 23.7
265 13730 90.9 3262 23.8
266 13556 89.8 3233 23.8
267 13324 88.2 3174 23.8
268 13114 86.9 3118 23.8
269 12895 85.4 3067 23.8
270 12639 83.7 3026 23.9
271 12309 81.5 2971 24.1
272 12004 79.5 2915 24.3
273 11637 77.1 2840 24.4
274 11120 73.6 2676 24.1
275 10669 70.7 2544 23.8
276 10245 67.9 2454 24
277 9704 64.3 2343 24.1
278 9160 60.7 2245 24.5
279 8623 57.1 2155 25
280 8041 53.3 2084 25.9
281 6859 45.4 1876 27.4
282 6181 40.9 1781 28.8
283 5566 36.9 1673 30.1
284 4999 33.1 1572 31.4
285 4448 29.5 1450 32.6
286 3876 25.7 1350 34.8
287 3286 21.8 1224 37.2
288 2642 17.5 1042 39.4
289 2119 14 876 41.3
290 1704 11.3 741 43.5
291 1276 8.5 587 46
292 964 6.4 467 48.4
293 715 4.7 360 50.3
294 504 3.3 271 53.8
295 308 2 164 53.2
296 194 1.3 90 46.4
297 126 0.8 53 42.1
298 78 0.5 32 41
299 56 0.4 23 41.1
300 34 0.2 12 35.3

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?
Download the data
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
spacefem.com
spacefem@spacefem.com

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.

learning to read

Sat Feb 2 11:42 AM by melsbells in Pregnancy & Parenting

Spacefem, thanks for the book suggestions.

Sonic, I like the way you described the sound a letter makes.



I asked a few early elementary school teachers I know this same question and wanted to share a bit of what they had to say.

They recommended starting with consonant-vowel-consonant words (CVC) with short vowel sounds, and focus on rhyming families (i.e. bat, cat, fat) and even including first consonant changes that don't make real words, like 'gat'. Then later introduce CVC with last letter changes (i.e. bad, bar, bat). They said we could try sight words at the same time and told me to do a search for the Fry sight word list.

After those CVC words aren't a problem, it was suggested to start adding an 'e' at the end of CVC words to change the vowel sound, an the meaning of the words, so introducing long vowels (i.e. cap->cape). Then after all that, we can start adding two consonants together and two vowels together. From there maybe come up with homonyms together, which can be a great way to introduce silent letters (i.e. new, knew).


How important is school?

Thu Nov 22 9:05 PM by Skeezy in Pregnancy & Parenting

I think the most important factor in any school is how much the teachers care about the students. Another important element is safety and how interactions between students can substract from learning. Many parents go to jail for quite lengthy sentences for trying to send to their kids to a safe good school.



I would say its very important, because what you learn shapes and molds yours views that make you who you are.


Unplanned, polyamorous pregnancy situation

Sun Apr 29 12:18 PM by metawidget in Pregnancy & Parenting

I'm glad you have been communicating and working things out. I wish you lots of health and love as you wrote the next chapter of this story.


I might be pregnant...

Fri Jan 5 3:16 AM by Aum in Pregnancy & Parenting


Aum, my partner and I were just discussing this. He was surprised by my taking the hard line that stopping BC or poking holes in condoms or something like that is rape, making the woman a rapist. Which should result in jail time, so she should lose custody, which should go to the father and now he has the choice of keeping the baby or putting them up for adoption.

It's unfortunate that you can't prove such a thing, but hopefully if it was actually taken seriously women would be less likely to do it because it would at least be explicitly called rape.


I understand how the justice system and the family courts would look at it. They see it as the man's sperm made it to the egg so somehow he wasn't protecting himself, he made the choice, yada yada. There's no way to prove that the woman was manipulative, withdrew BC, or "poked holes in the condom" (I think that's unheard of, but anyway).


When do you outsource parenting?

Sat Oct 14 7:47 PM by rowan in Pregnancy & Parenting

yeah I do a ton of supplemental history... :(


Sleep for babies after 6 months

Thu Jan 10 1:30 AM by Sonic# in Pregnancy & Parenting

Thank you for the stories. I try not to get caught up in comparisons, but it's so hard when someone else is like, "Oh yeah, they're sleeping through the night after six months, no problem!" and we're nudging each other when it's our turn to get up at night almost every night. Did I do something wrong? (The answer is probably no, but a lack of sleep makes it harder to get there mentally.)



I topped baby off tonight. He straight up drank 7 ounces of formula after his prunes. If he's an infiltrator, he's eating well for it. :)


How the 2nd pregnancy / labor was different from the first

Thu Sep 27 8:20 PM by antfancier in Pregnancy & Parenting

I haven’t been around for a long time, but I’m back and pregnant again. Only 6 weeks, so I can’t really comment much, but this time around it has been easier so far. Not easy, but considering I’m working and have a 2.5yr old (neither of which applied to last pregnancy), I thought I’d feel much worse. I still have ALL the symptoms and they all started at 3 weeks, just like last time (and the same as a chemical pregnancy I had too) but they don’t seem to be as constant as before. I’m really glad about that! The only thing that’s worse is back ache, ligament pain, general body aches. I assume it’s because my body is already exhausted and broken from my toddler.


posting pictures of kids and privacy

Wed Apr 25 7:29 AM by juliabonl17 in Pregnancy & Parenting

Usually, we don't share photos of our children in social media. Sometimes I can send some photos to close friends. I keep my personal life in quiet. Share with family only.


I had my 2nd baby!!!!

Wed Jan 3 8:21 PM by MFS in Pregnancy & Parenting

OMG BABY!



I am still dealing with the fact that your 11 year old is an actual 11 year old.


on being semi-pregnant

Tue Oct 3 7:18 PM by geldofc in Pregnancy & Parenting

congratulations!! i've never been pregnant but i'm jealous. i'm having baby fever lately.


kids' mail subscriptions

Wed Jan 9 6:41 PM by melsbells in Pregnancy & Parenting

We got the first box last week. Kid wanted to do the whole thing in one sitting, which was tough. He has a hard time stopping something, even when it's obvious he needs a break. He doesn't have the best conception of time yet either and kept talking about the box that would come tomorrow. So getting something once a month might help pin down the passage of time. As far as my concerns, we had a great opportunity (when he was disappointed that the Europe page didn't say anything about Finland) to talk about how a single page on a whole continent or even an individual country can't tell us what a place and culture is like. Bavaria was mentioned, so we also got to talk about how our German friend feels when people only think of Bavarian things when thinking of Germany, which she doesn't feel a connection to.


housemates + newborn = ?

Thu Aug 2 11:57 AM by melsbells in Pregnancy & Parenting

I live with my in-laws, and while there will certainly be a lot of differences from your situation, maybe there's enough similarities that my experience could be useful to you. I think the biggest thing is that everyone has their own space. Our house is sort of divided in two, so we can take the kid to our end during a tantrum. I think that distance helps, not just with in-laws not wanting to hear screaming, but as a sort of physical signal for the kid to calm down. We lived in an apartment when the kid was first born and our neighbors there probably heard more screaming/crying due to proximity.



My father-in-law spends a lot of time with the kid, mostly by choice. I sometimes wish we had more of a schedule, because at the moment, naps and bedtime are the only semi-guaranteed breaks for anyone. My spouse and father-in-law both work from home free-lance, so they don't actually have a schedule for when they need to be left alone, but at least my father-in-law has more warning with jobs scheduled out in advance.


My Ectopic Pregnancy

Tue Jan 23 8:47 PM by rowan in Pregnancy & Parenting

FYI we have a general culture in the pregnancy forum here about sharing similar stories as a way to offer support, and also about giving any medical knowledge that we've come across, since pregnancy is generally not talked about as much as it should be and you find information in random places. Since you haven't been around until now you probably didn't know that, and mels' post is well in line with forum guidelines and norms. Please don't go all mod martyr on us now that you're only just back. This is me as a friend speaking here, not with my modhat on.



I'm sorry for your loss. Ectopic pregnancies are scary, and I would like to go punch that first doctor in the face for you.



PPD is awful too. :( I hope you can get through it.


gender recognition

Thu Nov 2 1:03 PM by Nech in Pregnancy & Parenting


You can continue discussing with him the difference of a boy and a girl. Have him socialize too with the same gender. There's nothing wrong if you have go with opposite sex as long as he understands what/who he is.


So do you feel hanging out with the opposite gender at a young age can confuse a person's gender identity?


leftist parenting and gender [split from gender recognition]

Sat Sep 23 11:52 AM by Unvoiced_Apollo in Pregnancy & Parenting


gender recognition.">



If a boy who has a penis asks if he's a boy and you don't just say yes, then that's straight up lunacy.



What he decides to do with that boyhood or how he dresses is up to him. But if you're born with a penis you're a boy.



Making it airy fairy when, statistically, scientifically, less than 1% of 1% of children born have true gender dysphoria, is immoral and wrong. It's also a sign of our troubled times.


This is just my anecdotal experience but...



I have experienced bullying based on simply engaging in normal children's play with girls. Insults were attacks on both me and the girls. But I NEVER questioned my gender as a male. So if a child asks me if he's a boy and was identified biologically as one, I am going to question what influences are on the child before I answer.