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We have another baby on the way and I was thinking about asking this previously, but wasn't sure how common it was as our first child predates this site by about 4 years.

Now we have another on the way it has come up again and people keep telling us we shouldn't be announcing our pregnancy until the second trimester.

Their suggestion is that it is more likely that there will be complications in the first semester and this will ultimately lead to our embarrassment. This is usually mentioned quite abruptly as if this a regular occurrence and we will suffer the consequence of going around telling everyone.

Based on fact, in the developed world do more deaths happen during the first trimester or during the rest of the pregnancy including labor?

This would be for a healthy female aged 18 - 35.

I also don't know if this has any effect on the figures, but it should be assumed that during the first trimester a pregnancy is not identified until after 5 - 6 weeks has already passed. As nobody would go around announcing something that never happened if there was some sort of complication during that period.

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    Isn't it just common sense? Miscarriages are quite common. They tend to happen early, and you don't want to have to deal with all the people you've told. – Mike Dunlavey Jul 18 '11 at 1:02
  • Which region of the world do you live? I guess the risks of pregnancy aren't common over the world, and the cultural reaction differs much, from country to country. – user unknown Jul 18 '11 at 1:09
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    @user - As mentioned in my question, I am talking about the developed world. I am from Australia, but I assume trends in the US, UK, Australia and Eastern Euro countries won't be that different. – going Jul 18 '11 at 1:19
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    @Mike - They may be quite common very early on, but as mention above I am looking at after 6 weeks. From a few sites I've seen the risk from 6 weeks on is around 5% and in the second trimester its around 3%, not much difference. Do you have any facts / figures to back up your claims? – going Jul 18 '11 at 1:36
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    You may also want to factor in how comfortable you will be telling friends you have had a miscarriage. – DJClayworth Jul 18 '11 at 2:14
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Yes, the first trimester is the most risky one, as American on Pregnancy Association on miscarriage tell us:

Most miscarriages occur during the first 13 weeks of pregnancy. Studies reveal that anywhere from 10-25% of all clinically recognized pregnancies will end in miscarriage.

A bit more info about how the probability evolves is provided by a BBC Q&A Miscarriage:

The risk of miscarriage lessens as the pregnancy progresses. It decreases dramatically after the 8th week.

Compared to this, probability of later miscarriage (12-20 weeks) is 3 % and probability of stillbirth (after 20 weeks) is 1 %, see Buzzle Miscarriage Statistics:

  • About 75% of all miscarriages, occur during the first trimester only.
  • Chances of miscarriage during 12 to 20 weeks is only 3%.
  • Chances of stillbirth after 20 weeks drop to mere 1%.
  • Miscarriage statistics after heartbeat is less than 4%. If you hear a strong heart beat on the ultrasound around 9 to 12 weeks, then you have very little chance of miscarriage.

However, knowing the probability when miscarriage happens in not enough from a practical point of view, as you need to consider a possibility of a missed miscarriage, a miscarriage which is undetected for a few weeks, therefore in a normal situation, where you visit a doctor not more often then once per month, you may detect the miscarriage at the very end of the first trimester (anecdotally I know two couples who experienced this).

A missed miscarriage typically happens within the first 12 weeks of pregnancy, most often occurring soon after the fetus has been implanted in the rich lining of the uterus. With a missed miscarriage, the woman has no exterior symptoms of losing the pregnancy because the body fails to "notice" the loss of the baby. As a result, the fetal tissue is not immediately expelled by the uterus.

And last, which is perhaps not what you would expect from a skeptics site, but given the sensitivity of the subject, I think would be a shame to miss it (from Women's Health Misconceptions About Miscarriage):

If you think that you are alone when you miscarry - you aren't. You'll probably find, if you start to talk to your friends, many of them have miscarried as well.

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This is only part of an answer, hopefully others can provide more facts from around the globe. From my own searching, actual statistics are hard to find for miscarriage figures (this may be only in Australia).

In referring to this research done by Dr. Stephen Tong of Monash University:

Research was conducted on 696 asymptomatic women carrying one fetus who attended their first prenatal visit between 6 and 11 weeks of pregnancy.

  • The risk of miscarriage among the entire cohort was 11 of 696 (1.6%).
  • The risk fell rapidly with advancing gestation
  • 9.4% at 6 (completed) weeks of gestation, 4.2% at 7 weeks, 1.5% at 8 weeks, 0.5% at 9 weeks and 0.7% at 10 weeks

I would assume you won't be telling friends and family until you have been to a GP and confirmed your pregnancy and will likely be around 6/7 weeks after being assured that you have missed your most recent period.

It may be wise to hold off a couple of weeks, but by week 8 there is already quite a high chance that things will progress normally. This is still 4 weeks from the second trimester.

I personally think at 6 weeks and 9.4% you can still be justified in announcing to your friends and family early even if things don't work out. Assuming you are healthy and have not had previous complications or miscarriages.

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    It seems clear there is a large subjective component to the last paragraph. I can't get those numbers to add up; could you define them some more: 9.4% of what? Oh, and congratulations! I guess telling the Internet is easier than telling your family :-) :-) – Oddthinking Jul 18 '11 at 2:44
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    @Oddthinking - I agree the last sentence is subjective. The 9.4% was the percentage of participants who had a miscarriage during that week based on the research. My main point is that it should be reasonable for people to tell family and friends from after the 6 week mark as it is unlikely that they will miscarry at that point. People shouldn't feel pressured to keep it secret for 4 months and family and friends can safely spread and enjoy the news after 6 weeks due to low risk. – going Jul 18 '11 at 3:04
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    I still don't get the numbers, even after looking at the abstract. It seems 9.4% of all miscarriages between the first antenatal visit (6-11 weeks after gestation) and the 6 week mark. Huh? And given n=11, 9.4% of 11 = 1.034 women? Add selection bias, and the number is even less reliable. Mostly, however, this figure is the wrong one to look at. Should I delay from 6 weeks to 11 weeks to announce? 4.2+1.5+0.5+0.7=6.9% of miscarriages occur in that period, which is 6.9%*1.6%=0.11% of all pregnancies, which is the real issue. I don't trust that figure as I don't understand the original data. – Oddthinking Jul 18 '11 at 3:20
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    @Oddthinking - Unf. the link to full article requires payment. I understand your concern about the 9.4%. (As you calculated) The 6.9% is still significantly low and it is still correct (based on data provided) that after 8 weeks it is very low. Hopefully someone else can drag up some more data. – going Jul 18 '11 at 4:41
  • "The risk of miscarriage among the entire cohort was 11 of 696" This seems to differ a lot with other sources, which usually quote numbers in 10-25 range. What exactly is this number supposed to mean? How does it match with 9 % in 6 weeks? – Suma Feb 13 '13 at 8:05

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