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 3633 births resulting from inductions (out of 15339 total). Only 8% (275) 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, 12000/15339 (78.2%) of spontaneous labors had already happened. But only 1243 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 8239 spontaneous labors before 41 weeks and 3467 spontaneous labors after 41 weeks. If all 1243 inductions were added to that "spontaneous" count, that'd mean there were 4710 babies born after 41 weeks... not enough to tip the scales. What if all the inductions after 40 weeks (2118) were actually supposed to be spontaneous labors after 41 weeks? That'd mean 5585 babies would be born after 41 weeks. Remember, we'd need at least 8239 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 15339 100 3633 23.7
246 15308 99.8 3625 23.7
247 15283 99.6 3622 23.7
248 15258 99.5 3619 23.7
249 15223 99.2 3609 23.7
250 15186 99 3596 23.7
251 15149 98.8 3586 23.7
252 15122 98.6 3584 23.7
253 15056 98.2 3563 23.7
254 15012 97.9 3549 23.6
255 14953 97.5 3536 23.6
256 14898 97.1 3529 23.7
257 14849 96.8 3518 23.7
258 14789 96.4 3505 23.7
259 14709 95.9 3486 23.7
260 14577 95 3443 23.6
261 14466 94.3 3414 23.6
262 14353 93.6 3384 23.6
263 14230 92.8 3359 23.6
264 14090 91.9 3334 23.7
265 13948 90.9 3306 23.7
266 13769 89.8 3277 23.8
267 13532 88.2 3217 23.8
268 13319 86.8 3161 23.7
269 13097 85.4 3109 23.7
270 12837 83.7 3068 23.9
271 12501 81.5 3013 24.1
272 12192 79.5 2956 24.2
273 11822 77.1 2881 24.4
274 11296 73.6 2716 24
275 10839 70.7 2582 23.8
276 10409 67.9 2492 23.9
277 9858 64.3 2380 24.1
278 9307 60.7 2280 24.5
279 8762 57.1 2189 25
280 8173 53.3 2118 25.9
281 6972 45.5 1905 27.3
282 6285 41 1808 28.8
283 5659 36.9 1699 30
284 5078 33.1 1595 31.4
285 4515 29.4 1472 32.6
286 3936 25.7 1371 34.8
287 3339 21.8 1243 37.2
288 2685 17.5 1056 39.3
289 2155 14 888 41.2
290 1737 11.3 752 43.3
291 1304 8.5 597 45.8
292 983 6.4 474 48.2
293 730 4.8 365 50
294 513 3.3 275 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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EDD Icon Generator
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Weeks vs. Months Explained
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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.

Fundraising for St. Jude Children's Research Hospital

Wed Aug 14 5:27 PM by melsbells in Pregnancy & Parenting

Great job making your goal and helping out your teammate reach hers.


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.


When do you outsource parenting?

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

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


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).


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.


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.


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.