# What if I know my conception date?

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In the survey, 35 participants claim to know their exact conception date. This is rare; most due dates are measured from last menstrual period because it's easier to track. But the general question that always comes up is "Would my due date be more accurate if based off the conception date?"

On the main probability chart I found that due dates have about an 8-10 day standard deviation, meaning that the bulk of the babies are dispersed within plus or minus 10 days of their due date.

For this graph, I subtracted each babies birth date from his or her conception date, then added 14 days across the board because that's usually what we do when calculating a due date based on conception.

The standard deviation didn't improve much when compared to all the women in the survey. So bad news... even if you know the second your baby was conceived, your due date won't be any more accurate.

There is a related chart that compares LMP due dates with ultrasound-determined due dates. It also found no noticable difference in standard deviation.

The statistics right now are as follows:

• Mean: 279 (39W,6D)
• Median: 278 (39W,5D)
• Standard Deviation: 9.51 days
• Most popular days to give birth:
• 278 (39W,5D) (5 births, 14%)
• 287 (41W,0D) (3 births, 9%)
• 283 (40W,3D) (3 births, 9%)
• 276 (39W,3D) (2 births, 6%)
• 272 (38W,6D) (2 births, 6%)

### Data Table

The percentages are based on ALL births (including inductions)
DayWeekBirths Running TotalPercentRunning Total %
24535W,0D000 % 0 %
24635W,1D000 % 0 %
24735W,2D000 % 0 %
24835W,3D000 % 0 %
24935W,4D000 % 0 %
25035W,5D000 % 0 %
25135W,6D000 % 0 %
25236W,0D000 % 0 %
25336W,1D000 % 0 %
25436W,2D000 % 0 %
25536W,3D000 % 0 %
25636W,4D000 % 0 %
25736W,5D000 % 0 %
25836W,6D112.9 % 2.9 %
25937W,0D010 % 2.9 %
26037W,1D122.9 % 5.7 %
26137W,2D020 % 5.7 %
26237W,3D132.9 % 8.6 %
26337W,4D030 % 8.6 %
26437W,5D030 % 8.6 %
26537W,6D142.9 % 11.4 %
26638W,0D040 % 11.4 %
26738W,1D040 % 11.4 %
26838W,2D265.7 % 17.1 %
26938W,3D060 % 17.1 %
27038W,4D172.9 % 20 %
27138W,5D182.9 % 22.9 %
27238W,6D2105.7 % 28.6 %
27339W,0D0100 % 28.6 %
27439W,1D0100 % 28.6 %
27539W,2D0100 % 28.6 %
27639W,3D2125.7 % 34.3 %
27739W,4D1132.9 % 37.1 %
27839W,5D51814.3 % 51.4 %
27939W,6D0180 % 51.4 %
28040W,0D0180 % 51.4 %
28140W,1D1192.9 % 54.3 %
28240W,2D1202.9 % 57.1 %
28340W,3D3238.6 % 65.7 %
28440W,4D1242.9 % 68.6 %
28540W,5D0240 % 68.6 %
28640W,6D1252.9 % 71.4 %
28741W,0D3288.6 % 80 %
28841W,1D2305.7 % 85.7 %
28941W,2D2325.7 % 91.4 %
29041W,3D0320 % 91.4 %
29141W,4D0320 % 91.4 %
29241W,5D0320 % 91.4 %
29341W,6D1332.9 % 94.3 %
29442W,0D1342.9 % 97.1 %
29542W,1D1352.9 % 100 %
29642W,2D0350 % 100 %
29742W,3D0350 % 100 %
29842W,4D0350 % 100 %
29942W,5D0350 % 100 %
30042W,6D0350 % 100 %

### 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
spacefem.com
spacefem@spacefem.com

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.

### Clock-Ticking

Sat Aug 19 2:18 AM by lovernotafighter in Pregnancy & Parenting

Thank you everyone. :) Any info about egg-freezing is appreciated. Although, my wife can always donate hers too. Good luck, Sonic. :) Many prayers for you both! :)(sufiMYSTIC) *I'm back to my original profile, lovernotafighter.*

### bad reasons for having a baby

Tue Aug 1 1:47 AM by rowan in Pregnancy & Parenting

but I take them to restaurants so I know they end up hating 90% of the things they ask for.
:lol:

- kid would like a sibling

- maybe people are right about end of life stuff

That's about it. I hated being pregnant, the last time I was pregnant the hormones were... really awful. Plus kid is now pretty big so another one would be weird and we gave away all our stuff. ;)

### how do you travel?

Mon Jun 19 11:00 AM by DarkOne in Pregnancy & Parenting

We're traveling with a 2 yo and a 4yo this week. A 2 hr flight connecting to a 4 hr flight. I broke down and got tablets and headphones, now I just need to load them with movies/games. I'm packing treats and stickers and crayons and notepads. I'm almost positive I'll be carrying on a (very compactable) pillow, 'cause they don't give those out anymore on board. I'm banning toys that can roll several aisles fwd or back when inevitably dropped (besides the crayons). I was planning on gum for ascent/descent, but I think the suckers for the 2yo will be better. I'm so not looking forward to these flights. Maybe the kids will surprise me and be awesome. I'm not worried about the 4yo. But the 2yo...

### Bilingual Toddler

Wed May 3 10:19 PM by Nachos in Pregnancy & Parenting

Bilingualism! This is something I know a lot about! My last job was to speak English to my class in a partial immersion school and the kids picked up English so fast but spoke back to me in German. We worked on saying different words in German and in English and it meaning the same thing and I read English books to them. They differentiated pretty well but most of them came from a mono-lingual family background.

I can still highly recommend this book: (https://www.amazon.com/Third-Culture-Kids-Growing-Revised/dp/1857885252) for bilingual children. Some very good advice in there.

Also, keep speaking English! Toddlers forget fast when a language is no longer present.

Yay bilingualism!

### New parent help/suggestions

Sat Jan 14 10:07 PM by antfancier in Pregnancy & Parenting

I agree with everything lyra211 said and will add a few more.

Things you don't need:

Anything soft, fluffy or furry. My baby couldn't care less about minky blankets and soft toys. Plus they seem more gross to clean when they get covered in bodily fluids.

Clothes that look like adult clothes. It's so difficult to squeeze baby thighs into miniature corduroys or denim jeans which have no give to the fabric.

Baby washcloths. Babies make a disproportionate amount of mess so you need adult size washcloths to clean them up.

Things that were super useful:

A folding changing mat. I have a SkipHop one which has enough storage for wipes and diapers, which was all I needed to carry with me when I had a newborn. Now that he's bigger, I appreciate the larger size of the mat because the one that came with my diaper bag is way too small.

Balls. They were the first thing he played with and still his favourite toys. At the beginning he liked one made by Oball which was easy to pick up, and a soft fabric one which made a crinkly noise. Now he loves throwing a soft rubber ball and watching it bounce.

### Postpartum issues: things that can go wrong after

Wed Aug 9 5:24 PM by rowan in Pregnancy & Parenting

ugh that totes doesn't just happen during c-section. I had a friend who found out when she was having (other) surgery years later and they stitched her up since "they were in there anyway". Honestly I think I also have it but it doesn't cause problems *most* of the time (sometimes stabby pain but no one takes it seriously so idk).

### Just Can't Let It Go

Wed Jul 26 1:18 AM by Taurwen in Pregnancy & Parenting

We didn't find out specifically because we didn't want a lot of pink stuff if it was a girl.

Somehow MIL has still given us a ton of pink clothing that she'll change him into everytime she comes over.

I hate pink.

### Another baby stars

Thu Jun 15 6:54 AM by StarsInUrEye in Pregnancy & Parenting

Thanks for the congratulations and encouragement.

I had an appointment with the obgyn today. He seems to think I'm even farther along than he originally thought. I didn't have an ultrasound. He just went by the size of my uterus. It's well over my belly button now. He's sending me to a high risk Dr. Asap and then I'm suppost to see him again on the 29th. By then he said they will have a better idea as to how far along I actually am. So far the pregnancy is going well. I did have complications with my first one and went to a specialist but this time I'm being referred to one because I'm old lol. They automatically send women when they are 35 and older.

### What did I just say?

Wed Mar 15 12:25 PM by mariareese in Pregnancy & Parenting

Looking to know about the system and biology :D hehe ..

### Activities for 1-3 yo's

Sat Jan 14 7:07 PM by antfancier in Pregnancy & Parenting

I find theimaginationtree.com has lots of inspiring ideas. Some look like they take quite a bit of prep, but if you're doing it for a whole class then it might be worth it. You can sort activities by age as well so it's easier to search.

### How to deal with opinionated toddlers (or babies or kids)

Tue Aug 1 1:57 AM by rowan in Pregnancy & Parenting

Ooof. My kid is very social, needs to be around someone all the time. It's ... challenging, as you've found. It does get better as they gain their own interests. But it took a long time to get past clingy.

Yes. After bedtime.

Also, honestly the only way we made it through was we would take turns being the center of focus. We still do this, divide and conquer (and she's only one kid, hell). Also, I know people are like really limit screen time BUT if you really need to get something done one episode of e.g. Daniel Tiger or Paw Patrol or whatever isn't gonna be too bad. I think DarkOne has some good ideas too.

Good luck.

### Happiest Baby on the Block

Wed Jul 12 4:52 PM by antfancier in Pregnancy & Parenting

My mum gave me 'Your Baby and Child' by Penelope Leach, which is what she used when she had me. It covers from birth to five years. I read the first section about newborns in preparation. After having the baby, I realised I have zero time or brain power to do anything so I never got around to the rest of it. In general, I liked the book though. It's a simple overview and has nice color photos.

### To all Moms: Where do you go for financial concerns?

Tue May 9 4:18 PM by rowan in Pregnancy & Parenting

My father in law does financial advising so we kind of have an in-house advisor? But seriously someone with expertise is great. There are various "how to do finances" through our local community ed, which I'd probably consider if I didn't already have someone to ask. Maybe something like that near you? Libraries also sometimes have programs.

Also I know you can do wills and stuff on your own but honestly I found it super useful to talk through it with a lawyer who does that. She thought of things we never would have. (hm really should revisit now that kid is older) It was a one time fee and not that bad.

We do most of our banking through a credit union. Have been happy with them. We refinanced our mortgage through them when we did that. I remember the big credit union bust ages ago, but there are lots more protections in place now and big banks can be pretty awful.

### stuffed animals

Thu Feb 23 1:20 AM by antfancier in Pregnancy & Parenting

My brother's favorite stuffed animal was a thing we called 'gerbil'. I actually don't know what it was because we found it in the street (not sure what my mum was thinking in allowing him to pick it up, let alone keep it) and it had already lost an eye and was unidentifiable, but he became really attached to it. We almost missed a flight once because he dropped it in the airport and we had to go back to look for it.

Today for the first time my 11month old showed interest in a stuffed animal. Just before Christmas we received a box from Amazon with a giant bear inside. No gift wrap, no note. Just a bear the size of my child. It's been sat in his room and ignored completely, despite him exploring literally everything else that is in there. Then, out of the blue, he made a beeline for it and tried to pull its eyes out.

### tactile stuff

Wed Jan 4 6:14 AM by Neko in Pregnancy & Parenting

All the pliable/crafty stuff I can think of has been mentioned. ETA: I lied. Bread dough!

But if generally tactile surfaces also apply, mermaid sequin pillows are comforting. It was one of my impulse buys at a department store about a month ago. I couldn't stop petting the display. The sequined side seemed like it wouldn't be comfortable to rest on but it hasn't been an issue. My stepdad really likes them so I got him one for giftmas and he said it helps distract him when chronic pain keeps him awake at night. https://www.etsy.com/listing/470423508/dragon-mermaid-reversible-luxury-sequin?ref=shop_home_active_40

I haven't field tested them on my nieces and nephews yet. That could be fun.