Miscarriage statistics

It is extremely difficult to obtain accurate statistics on miscarriage for several reasons, the main one being that the majority of miscarriages occur before the mother realises she is pregnant. If these unrecognised miscarriages are included, it is estimated that 40–60% of pregnancies ends in miscarriage.1 However, even if we restrict the figures to recognised pregnancies, the miscarriage rate is difficult to determine because many remain unreported. The following statistics are our best estimates based on the most reliable sources available. They may well be underestimates.

Incidence of miscarriage

1 in 4 women who get pregnant will experience a miscarriage.²
At least 15% of all pregnancies ends in a miscarriage.^2,3

Relative risk of miscarriage⁴

First pregnancy:                                                                     5%
Last pregnancy a live birth:                                                     5%
All previous pregnancies resulted in live birth:                          4%
Last pregnancy miscarried:                                                    19%
All previous pregnancies miscarriaged:                                   24%

Risk of miscarriage at various ages⁵

Age: 12-19 years    Miscarriage Risk: 11%
Age: 20-24 years    Miscarriage Risk: 9%
Age: 25-29 years    Miscarriage Risk: 10%
Age: 30-34 years    Miscarriage Risk: 12%
Age: 35-39 years    Miscarriage Risk: 20%
Age: 40-44 years    Miscarriage Risk: 41%
Age: 45 or more     Miscarriage Risk: 75%

Sources:
1. Kallen B. The Epidemiology of Human Reproduction. Boca Raton: CRC Press; 1988.
2. Warburton W, Fraser FC. Spontaneous Abortion Risks in Man: Data from Reproductive Histories Collected in a Medical Genetics Unit. American Journal of Human Genetics 1964;16(1):1–25. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1932458/pdf/ajhg00547-0015.pdf)
3. NHS Direct Wales Encyclopaedia. Miscarriage. (http://www.nhsdirect.wales.nhs.uk/encyclopaedia/m/article/miscarriage/)
4. Regan L, et al. Influence of past reproductive performance on risk of spontaneous abortion. BMJ 1989;299:541–5. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1837397)
5. Nybo Anderson A, et al. Maternal age and fetal loss: population based register linkage study. BMJ 2000; 320(7251):1708–12. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC27416)