Chances of Miscarriage After Normal Pregnancy

Women With Children Are Probably at Lower Risk for Future Miscarriage

Pregnant mid adult woman holding daughter
Getty Images/Cultura RM/Tosca Radigonda

Almost every pregnant women worries about miscarriage, at least in the beginning. This is understandable considering the scary statistics floating around out there that between 15% and 30% of confirmed pregnancies end in miscarriage, plus the even scarier statistic that claims 70% to 75% of conceptions end in miscarriage.

But if you have one or more living children, you may not need to worry quite that much, claims a 1989 study.

British researchers examined the effects of women's previous pregnancy history on the risk of miscarriage in the next pregnancy, and they found that in women whose previous pregnancy had ended in a live birth, the risk of miscarriage the next time around was only 5% (1 in 20). With all previous pregnancies having ended in live birth, the risk was even lower still at 4% (1 in 25).

Obviously the risk of miscarriage will never be zero. But in this age of what is often too much information, it can be nice to know when you fall in a lower risk group.

What's the Main Cause of Miscarriage?

Various risk factors for miscarriage exist, many of which have yet to be elucidated. Miscarriages during the first trimester of pregnancy are usually due to chromosomal abnormalities. In fact 2 of 3 miscarriages are attributable to such abnormalities.

Chromosomes are like hard drives that contain all the information your body needs for development.

They are blocks of genetic information that serve as the seeds of life.

During conception, when the gametes, or egg and sperm which contain chromosomes, meet, sometimes either too many or too few chromosomes result. Often when the number of chromosomes is off, the pregnancy is nonviable and can't survive, resulting in miscarriage.

Of note, not all pregnancies that involve abnormal chromosome counts go on to miscarry. For example, Edward's syndrome is caused by trisomy 18, or triplicate copies of chromosome 18, and Down's syndrome is caused by trisomy 21, or triplicate copies of chromosome 21. Nevertheless, babies with abnormal chromosome counts usually experience profound complications which can result in early death. For instance whereas people with Down's syndrome can go on to live to middle age, the majority of babies with Edward's syndrome that make it to birth die within the first few days of life.

What Are Other Causes of Miscarriage?

Although chromosomal problems are the most common cause of miscarriage, there are other things that can result in miscarriage including the following:

  • medications (for example, NSAIDs, retinoids and methotrexate);
  • abnormalities in the shape of the womb.

Miscarriages due to chromosomal problems occur during the first trimester. However, the infections and chronic medical conditions listed above can result in miscarriage during the second trimester.

Factors Unrelated to Miscarriage

Often there's nothing that you can do to prevent a miscarriage, as in the case of chromosomal abnormalities. However, some miscarriage risk factors are modifiable, such as smoking, drug and alcohol cessation during pregnancy. In addition to these non-modifiable and modifiable risk factors, there's a lot of buzz about things that have nothing to do with miscarriage, including the following:

  • shock or fright
  • depression
  • emotional stress
  • lifting or straining
  • exercise
  • sex
  • spicy foods


Regan, L., P. R. Braude and P. L. Trembath. "Influence of past reproductive performance on risk of spontaneous abortion." BMJ 1989;299;541-545.

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