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Miscarriage Statistics: Is It True That 70% of Pregnancies End in Miscarriage?

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Updated July 03, 2014

Question: Miscarriage Statistics: Is It True That 70% of Pregnancies End in Miscarriage?

The news -- or even your friends -- may inform you of miscarriage statistics. If you have heard the somewhat scary sounding claim that 70% of all pregnancies end in miscarriage, you might be wondering how the human race is even still around. But fear not. That number does not reflect the actual odds of miscarriage after you are confirmed to be pregnant.

Answer:

If you search on miscarriage statistics at all, you can find claims that anywhere between 10 and 70% of all pregnancies end in miscarriage. These estimates are based on different criteria and different definitions of pregnancy. If you consider pregnancy to begin at implantation rather than fertilization of the egg, the odds of miscarriage will always be lower than 70%.

Some of the higher estimates of the rates of chromosomal abnormalities in fertilized eggs and the rates of very early miscarriage come from studies of embryos created by couples seeking IVF for infertility. Those studies tend to find very high rates of chromosomal abnormalities in fertilized eggs, but couples with trouble conceiving may well have different health factors that couples who conceive without difficulty. In addition, it is hard to say whether eggs fertilized in a lab can be compared to eggs fertilized naturally inside a woman's body.

Still, it does appear true that the majority of conceptions do not make it to term. In one oft-cited study from 1988, researchers used extremely sensitive hCG tests throughout the menstrual cycles of women who were trying to conceive and who had no evidence of infertility. In that study, researchers found evidence that about 22% of all conceptions did not implant; the women had very tiny increases in hCG at the time implantation would have been expected, but not enough to be picked up by a typical pregnancy test. Of the conceptions that did implant and result in a clinically recognizable pregnancy, 31% ended in miscarriage.

If you are pregnant and trying to figure out your odds of miscarriage, keep in mind that a standard home pregnancy test is not going to detect a fertilized egg that does not implant in your uterus. Thus, by the time a pregnancy test confirms that you are pregnant, the odds of miscarriage will be more along the lines of 30%. That might sound high to you too, but keep in mind that the odds of a good outcome improve as your pregnancy progresses further along.

Sources

Macklon, N.S., J.P.M. Geraedts, and B.C.J.M. Fauser, "Conception to ongoing pregnancy: the 'black box' of early pregnancy loss." Human Reproduction Update 2002. Accessed 26 Sept 2008.

Wilcox, A.J., C.R. Weinberg, J.F. O'Connor, D.D. Baird, J.P. Schlatterer, R.E. Canfield, E.G. Armstrong, and B.C. Nisula, "Incidence of early loss of pregnancy." NEJM Jul 1988. Accessed 26 Sept 2008.

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