Daily odds of pregnancy miscarriage

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This can be an upsetting topic, but after passing a pregnancy test and facing so much uncertainty about my future I just wanted something to make me feel a little more... in control. For me, that's statistics. So based on some human embryo survival rates - overall and at 6, 8, and 10 weeks, I did some curve matching to calculate the risk of miscarriage at each day of an early pregnancy. The data here is based on a study of 600 women who were tested daily for pregnancy while trying to conceive, so early pregnancies were all evaluated for survival rate. The numbers are an estimate, but they're something.

The following dates are based on an estimated LMP of August 10th, 2012.

Change LMP:
Month Day Year
Date Progress Overall probability of miscarriage
Friday August 31st, 2012 3W, 0D 33%
Saturday September 1st, 2012 3W, 1D 32.9%
Sunday September 2nd, 2012 3W, 2D 32.6%
Monday September 3rd, 2012 3W, 3D 32%
Tuesday September 4th, 2012 3W, 4D 31.3%
Wednesday September 5th, 2012 3W, 5D 30.3%
Thursday September 6th, 2012 3W, 6D 29.2%
Friday September 7th, 2012 4W, 0D 28%
Saturday September 8th, 2012 4W, 1D 26.6%
Sunday September 9th, 2012 4W, 2D 25.2%
Monday September 10th, 2012 4W, 3D 23.6%
Tuesday September 11th, 2012 4W, 4D 22.1%
Wednesday September 12th, 2012 4W, 5D 20.5%
Thursday September 13th, 2012 4W, 6D 18.9%
Friday September 14th, 2012 5W, 0D 17.3%
Saturday September 15th, 2012 5W, 1D 15.8%
Sunday September 16th, 2012 5W, 2D 14.4%
Monday September 17th, 2012 5W, 3D 13%
Tuesday September 18th, 2012 5W, 4D 11.7%
Wednesday September 19th, 2012 5W, 5D 10.5%
Thursday September 20th, 2012 5W, 6D 9.4%
Friday September 21st, 2012 6W, 0D 8.4%
Saturday September 22nd, 2012 6W, 1D 7.5%
Sunday September 23rd, 2012 6W, 2D 6.6%
Monday September 24th, 2012 6W, 3D 5.9%
Tuesday September 25th, 2012 6W, 4D 5.3%
Wednesday September 26th, 2012 6W, 5D 4.7%
Thursday September 27th, 2012 6W, 6D 4.3%
Friday September 28th, 2012 7W, 0D 3.9%
Saturday September 29th, 2012 7W, 1D 3.5%
Sunday September 30th, 2012 7W, 2D 3.2%
Monday October 1st, 2012 7W, 3D 3%
Tuesday October 2nd, 2012 7W, 4D 2.8%
Wednesday October 3rd, 2012 7W, 5D 2.6%
Thursday October 4th, 2012 7W, 6D 2.5%
Friday October 5th, 2012 8W, 0D 2.4%
Saturday October 6th, 2012 8W, 1D 2.3%
Sunday October 7th, 2012 8W, 2D 2.2%
Monday October 8th, 2012 8W, 3D 2.2%
Tuesday October 9th, 2012 8W, 4D 2.1%
Wednesday October 10th, 2012 8W, 5D 2.1%
Thursday October 11th, 2012 8W, 6D 2.1%
Friday October 12th, 2012 9W, 0D 2.1%
Saturday October 13th, 2012 9W, 1D 2%
Sunday October 14th, 2012 9W, 2D 2%
Monday October 15th, 2012 9W, 3D 2%
Tuesday October 16th, 2012 9W, 4D 2%
Wednesday October 17th, 2012 9W, 5D 2%
Thursday October 18th, 2012 9W, 6D 2%
Friday October 19th, 2012 10W, 0D 2%
Saturday October 20th, 2012 10W, 1D 2%
Sunday October 21st, 2012 10W, 2D 2%
Monday October 22nd, 2012 10W, 3D 2%
Tuesday October 23rd, 2012 10W, 4D 2%
Wednesday October 24th, 2012 10W, 5D 2%
Thursday October 25th, 2012 10W, 6D 2%
Friday October 26th, 2012 11W, 0D 2%
Saturday October 27th, 2012 11W, 1D 2%
Sunday October 28th, 2012 11W, 2D 2%
Monday October 29th, 2012 11W, 3D 2%
Tuesday October 30th, 2012 11W, 4D 2%
Wednesday October 31st, 2012 11W, 5D 2%
Thursday November 1st, 2012 11W, 6D 2%
Friday November 2nd, 2012 12W, 0D 2%
Saturday November 3rd, 2012 12W, 1D 2%
Sunday November 4th, 2012 12W, 2D 2%
Monday November 5th, 2012 12W, 3D 2%
Tuesday November 6th, 2012 12W, 4D 2%
Wednesday November 7th, 2012 12W, 5D 2%
Thursday November 8th, 2012 12W, 6D 2%

Future probability of miscarriage at a given day

Notes and disclaimers

All numbers are estimates. If you have better research, drop me an e-mail (spacefem@spacefem.com).

I used information from two studies to make my assumptions: Wilcox AJ, Baird DD, Weinberg CR (1999). "Time of implantation of the conceptus and loss of pregnancy." and Wang X, Chen C, Wang L, Chen D, Guang W, French J (2003). "Conception, early pregnancy loss, and time to clinical pregnancy: a population-based prospective study.". I was not able to obtain full access to the second one, but based on citations I believe I had the numbers I needed for this.

The studies analyzed women who were trying to conceive for the first time.

There is a page of good studies here: https://sites.google.com/site/miscarriageresearch/miscarriage-general that compares risks based on age, whether you've heard a heartbeat, previous miscarriage, and hosts of other factors.

Charts are generated by flot.

Recent Comments

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spacefem's guide to baby-led weaning

Sun Feb 7 10:39 PM by antfancier in Pregnancy & Parenting

Just got back from an infant first aid class. Current guidelines (in the USA) now say you should not use any kind of finger sweep (for adults and infants) - it's better to let the body try to clear the obstruction itself. The only time you intervene is when the airway is completely obstructed and they cannot breathe. But the teacher did say it's hard not to step in when you see your baby gagging, so if you really can't stop yourself then use a finger and thumb 'pincer' rather than a single finger sweep (which poses a higher risk of pushing the obstruction further down the throat).


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Tue Feb 2 11:37 AM by Aum in Pregnancy & Parenting

My great aunt had a baby while on the toilet... but then, she had 19 children in total so I'm sure by baby 10 it wasn't that big of a deal.


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One thing I do now that I wish I had done earlier on (though not sure I could have done in the first 6 months due to brain fog), is if I find myself thinking "I wish I could do X" or "I wish I had time for..." even if it's a fleeting thought, I write it down. Well actually I put it in my toodledo list, which I can access on my phone/computer/wherever. Then when I find time I'm like soooo what do I do again? Oh yeah! I wanted to do this thing! I mean, as simple as "read book" or "bake a thing" or something.

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Yeah, I went back and checked some sources -- here's the table that I sort of remembered from when I was going through the ectopic scare:
http://www.advancedfertility.com/ectopic.htm
So, half of ectopic pregnancies never get above an hCG level of 1,000, and only 9% ever make it above 10,000. Needless to say, the ones that do keep rising to those very high levels tend to be the scary ones, since those are the ones that keep growing and can cause things like tubal ruptures.

I can't link to it because it's subscriber only, but Up To Date (which has reviews of the most recent medical studies) has the following to say about the hCG threshold of 2,000 (some practices use 1,500 instead) and diagnosis of ectopic pregnancy:

The diagnostic criteria depend upon the relationship to the hCG discriminatory zone (serum hCG level above which a gestational sac should be visualized by TVUS if an IUP is present). The hCG level of the discriminatory zone varies, but in most institutions it is 1500 to 2000 IU/L (see 'Discriminatory zone' above and 'Clinical protocol' above):


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^ You'd have to pick something like heavy metal or drum & bass. Your kid would turn out all punk as a result, so it's win-win!


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