What are the Reasons and Causes of Miscarriage

Author: Dr Peter England, Obstetrician and Gynaecologist

Miscarriage is common. But, what causes a miscarriage? In this post I discuss a number of reasons miscarriage may occur.

Remember, miscarriage or loss of early pregnancy is common. 

Miscarriage occurs in:

• 20% of pregnancies for women aged in their 20s
• 25% of pregnancies for women in their 30s
• In Over 30% of spontaneous pregnancies for women aged 40 or over.

Most miscarriages are due to an abnormality in the number of chromosomes. Our cells have 46 chromosomes and 46 pieces of DNA within them. Around 70% of miscarriages (upon testing) have an extra chromosome. This equates to a couple of thousand extra active genes, that shouldn’t be present, which leads to failure of pregnancy (a miscarriage).

Miscarriage also occurs when the baby has the right number of chromosomes, but one of the chromosomes has a defect. If a piece of a chromosome is missing, it’s called a deletion and can cause a critical block to safe development.

Medical illness and medical disorders can also impact miscarriage. For instance, poorly managed diabetes or thyroid gland abnormality. Likewise, autoimmune disorders (i.e. SLE) can impact miscarriage rates – screening is available for this, and can be discussed with your doctor.

Age can also be a contributing factor in miscarriage rates. For women over 35 years, a lack of adequate hormone production in the early months of pregnancy, until the placenta has been established can result in a pregnancy loss.

Your ovaries have a role in producing hormones to support your pregnancy and can struggle to do this more as you get older, your doctor may discuss hormone support if this impacts you.

If you have had a miscarriage and would like know more about what causes a miscarriage or to discuss a future pregnancy, give the rooms a call to book an appointment time.

Author: Dr Peter England, Obstetrician and Gynaecologist.
Read more about Dr Peter England