Average day of spontaneous labor vs. age of mother at time of birth

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I read somewhere that maternal age has something to do with when labor sets in, so I included it in the survey. I found nothing terribly interesting or conclusive.

This sort of validated my decision to keep the survey simple and not consider every little thing in the world that people are curious about. Could the average day change depending on your age, ethnicity, whether you were on the pill, country of origin, etc? Maybe. But we're talking about something where with a standard deviation of over a week here... about the same number of people give birth on day 279 as on day 287. So if some random thing changes the average by 2 days will that knowledge help make your due date any more accurate? I'm thinking no.


Data table - Average lenth of pregnancy per age

Age# of participantsAverage day of spontaneous laborAverage day including ± 1 year of age
12 1 29041W,3D27739W,4D
12.5 1 28741W,0D27739W,4D
13 2 26437W,5D27238W,6D
13.5 1 28340W,3D27138W,5D
14 1 27339W,0D27339W,0D
14.5 3 26337W,4D27439W,1D
15 10 27038W,4D27539W,2D
15.5 13 27739W,4D27539W,2D
16 24 27639W,3D27539W,2D
16.5 27 27739W,4D27539W,2D
17 69 27539W,2D27539W,2D
17.5 55 27639W,3D27639W,3D
18 68 27339W,0D27639W,3D
18.5 79 27639W,3D27639W,3D
19 106 27639W,3D27639W,3D
19.5 110 27639W,3D27639W,3D
20 121 27639W,3D27639W,3D
20.5 159 27639W,3D27639W,3D
21 157 27739W,4D27639W,3D
21.5 154 27739W,4D27639W,3D
22 174 27739W,4D27739W,4D
22.5 166 27739W,4D27739W,4D
23 178 27639W,3D27739W,4D
23.5 180 27739W,4D27739W,4D
24 173 27939W,6D27739W,4D
24.5 200 27639W,3D27739W,4D
25 194 27739W,4D27739W,4D
25.5 184 27939W,6D27839W,5D
26 204 27739W,4D27839W,5D
26.5 219 27839W,5D27839W,5D
27 269 27839W,5D27839W,5D
27.5 271 27939W,6D27839W,5D
28 256 27939W,6D27939W,6D
28.5 267 27839W,5D27939W,6D
29 296 27939W,6D27939W,6D
29.5 284 27939W,6D27939W,6D
30 267 27939W,6D27939W,6D
30.5 272 27839W,5D27939W,6D
31 251 27939W,6D27939W,6D
31.5 229 28040W,0D27939W,6D
32 231 28040W,0D27939W,6D
32.5 232 28040W,0D28040W,0D
33 194 28040W,0D28040W,0D
33.5 172 28040W,0D28040W,0D
34 172 27939W,6D28040W,0D
34.5 128 27939W,6D28040W,0D
35 97 28040W,0D28040W,0D
35.5 84 28140W,1D28040W,0D
36 73 28040W,0D28040W,0D
36.5 73 28040W,0D28040W,0D
37 61 28240W,2D28040W,0D
37.5 53 28040W,0D28040W,0D
38 57 27939W,6D28040W,0D
38.5 47 28040W,0D28040W,0D
39 37 28240W,2D28040W,0D
39.5 37 28040W,0D28040W,0D
40 36 28140W,1D28040W,0D
40.5 23 28140W,1D28040W,0D
41 51 27939W,6D27939W,6D
41.5 46 27839W,5D27939W,6D
42 36 27839W,5D27939W,6D
42.5 21 28040W,0D27839W,5D
43 29 27839W,5D27839W,5D
43.5 20 27739W,4D27839W,5D
44 12 27439W,1D27839W,5D
44.5 13 28140W,1D27839W,5D
45 10 28140W,1D27839W,5D
45.5 9 27639W,3D27839W,5D
46 1 28640W,6D28040W,0D

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?
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
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Recent Comments

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you are invited to join our pregnancy forum. We are dedicated to answering complicated questions as logically as we possibly can.

Kids are full of LIES

Sun May 22 2:29 PM by rowan in Pregnancy & Parenting

Don't be silly monk, everyone knows a good conglomerate goes better with milk


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Wed May 11 3:39 PM by rowan in Pregnancy & Parenting

One of my friends is part of this magazine. She didn't write this one but it's pretty hilarious.

http://theoffingmag.com/wits-end/pregna ... cool-moms/

Anyone want to come up with our own "Guidebook" titles?

spoiler:
the one about inducing labor by setting your hair on fire is my favorite


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Thu Apr 28 9:21 PM by Sonic# in Pregnancy & Parenting

I don't think it's a cause for immediate concern, but my experience would lead me to talk to a doctor about it. I didn't have a stutter when I was 2. I had language delay. I didn't learn language when kids typically do. Needless to say, I was a very frustrated little kid. When my parents and my pediatrician caught on to it, I had to spend a few years seeing a speech pathologist.

I've read that stuttering is at least partly psychological, but I really can't say more than that. If nothing else, I'd just want to know that his frustration is a necessary part of development like teething and not something that can be avoided.


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Tue Mar 29 2:48 AM by Amuro in Pregnancy & Parenting

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Tue Mar 8 9:16 PM by antfancier in Pregnancy & Parenting

I just had a look at your article. :thumbup:
As you say, many comments have been deleted, but that's probably for the best otherwise I'd get mad.

I'm about to have my first child and have had some similarly surprising responses from people when I explain I'm going to be a SAHM; everything from admiration to unsolicited suggestions that a nanny is better than daycare. When I explain that the reason is that I acut ally want to work but my earnings from my two part time jobs would barely cover childcare, it always gets awkward. And then they suggest the whole home daycare/nanny thing again. Even if I could afford it, I'd rather choose the daycare because they have facilities and resources that I don't (I live in a basement apartment, with pretty minimalist furnishings).

I get it. People have strong beliefs about what is 'best', but it's not a one-size-fits-all scenario. And holy crap! If a woman wants and is able to work after having kids, why on earth shouldn't she?


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I'll take more posts here! I'm almost ready to give birth to my second, and I swear some parts are less scary because I know what's coming, but most of it is more scary because I do. What I do wish I'd really understood the first time is how short all the horrible baby phases are, in the long run, and how little you care about mommy wars BS like formula/breast milk after a very brief time.


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When my son's cord fell off a few weeks ago, I put it on the counter next to his changing pad then promptly forgot about it. I've no idea where it is now.


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Our behavioralist also recommended Prozac, which took a long time to get the dose right, but has helped the dog be less reactionary and neurotic.


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