Over the past 40 years, 3.5 million pregnancies have been registered in Denmark. A new study has examined how many of these pregnancies ended with the woman having a miscarriage. The researchers were able to monitor women throughout their fertile period, and they examined how many women are referred for 0, 1, 2, and 3 or more miscarriages.
A total of 337,008 miscarriages were registered in the study period, corresponding to 9.6% of the registered pregnancies. The percentage of miscarriages rose from 7.5% in 1978-79 to 10.7% in 2000, before declining to 9.1 % in 2017.
Risk rises with age
The percentage of pregnancies referred with a miscarriage rose gradually from 3.9% of women aged 10-14 years to 26.9% of women aged 45-49 years. This corresponds to a seven-fold increase in risk with increasing age.
Among the women monitored throughout their fertile period, the researchers found the following distribution of miscarriages:
• Women never referred with miscarriage: 77%
• Women with 1 miscarriage: 18%
• Women with 2 miscarriages: 4%
• Women with 3 or more miscarriages: 1%
More than three out of four women had never had a miscarriage which they themselves experience as a loss, and for which they were referred to a hospital.
The accumulated number of miscarriages for women of different ages is illustrated in the first figure below. How far women are in their term when they are referred with a miscarriage is illustrated on the second figure below. This shows that 11.1% were referred before their eighth week of pregnancy in 1995-99, rising to 23.6% in 2015-17.
The study was conducted by physicians at Rigshospitalet and Hvidovre Hospital. Further information can be obtained from Professor Øjvind Lidegaard, Department of Gynaecology, Rigshospitalet.