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 3597 births resulting from inductions (out of 15222 total). Only 8% (274) of the inductions were at or past 42 weeks, 0 D. By that time, 96.6% of all spontenous labors have already happened. At 41 weeks 0 days, 11905/15222 (78.2%) of spontaneous labors had already happened. But only 1232 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 8180 spontaneous labors before 41 weeks and 3445 spontaneous labors after 41 weeks. If all 1232 inductions were added to that "spontaneous" count, that'd mean there were 4677 babies born after 41 weeks... not enough to tip the scales. What if all the inductions after 40 weeks (2096) were actually supposed to be spontaneous labors after 41 weeks? That'd mean 5541 babies would be born after 41 weeks. Remember, we'd need at least 8180 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 15222 100 3597 23.6
246 15191 99.8 3589 23.6
247 15166 99.6 3586 23.6
248 15141 99.5 3583 23.7
249 15106 99.2 3573 23.7
250 15069 99 3560 23.6
251 15033 98.8 3551 23.6
252 15006 98.6 3549 23.7
253 14940 98.1 3528 23.6
254 14897 97.9 3515 23.6
255 14839 97.5 3502 23.6
256 14785 97.1 3495 23.6
257 14737 96.8 3484 23.6
258 14677 96.4 3471 23.6
259 14598 95.9 3452 23.6
260 14466 95 3409 23.6
261 14357 94.3 3380 23.5
262 14244 93.6 3350 23.5
263 14124 92.8 3326 23.5
264 13985 91.9 3302 23.6
265 13844 90.9 3275 23.7
266 13667 89.8 3246 23.8
267 13431 88.2 3186 23.7
268 13221 86.9 3130 23.7
269 13000 85.4 3079 23.7
270 12742 83.7 3038 23.8
271 12408 81.5 2983 24
272 12102 79.5 2927 24.2
273 11733 77.1 2852 24.3
274 11212 73.7 2688 24
275 10757 70.7 2556 23.8
276 10330 67.9 2466 23.9
277 9786 64.3 2355 24.1
278 9241 60.7 2257 24.4
279 8698 57.1 2167 24.9
280 8113 53.3 2096 25.8
281 6921 45.5 1887 27.3
282 6237 41 1792 28.7
283 5614 36.9 1683 30
284 5044 33.1 1582 31.4
285 4487 29.5 1460 32.5
286 3913 25.7 1360 34.8
287 3317 21.8 1232 37.1
288 2671 17.5 1049 39.3
289 2144 14.1 883 41.2
290 1727 11.3 747 43.3
291 1296 8.5 592 45.7
292 977 6.4 470 48.1
293 727 4.8 363 49.9
294 511 3.4 274 53.6
295 310 2 164 52.9
296 196 1.3 90 45.9
297 128 0.8 53 41.4
298 80 0.5 32 40
299 58 0.4 23 39.7
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

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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

Wed May 22 8:34 PM by Nachos in Pregnancy & Parenting

Late to the party, sorry.



When I worked in a biligual Kita, the kids picked up loads from simply being read to and pointing out the different things. Sometimes a question came up ("that is a pferd", "it's called horse in English", "ok horse") and it's good to know both languages to understand what the kid is saying, but reading is a good together activity :)


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.