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Why do miscarriages happen?

why miscarriages happen

Most miscarriages happen due to chromosomal abnormalities in the fertilised egg. If the egg or sperm has the wrong number of chromosomes, the fertilised egg is unable to develop properly and this results in a miscarriage. Other causes can be failure for the egg to implant in the womb, lifestyle factors or underlying health conditions.

Why do early miscarriages happen?

Miscarriage usually occurs within the first 20 weeks of pregnancy.

There are many reasons why they happen, and sometimes the cause isn’t identified, but the first 12 weeks are the most important for establishing a pregnancy

Sometimes a miscarriage can occur so early that the woman is unaware that it has happened at all. Many fertilised eggs are lost during implantation, for example, which means the woman goes on to have her period at around the expected time.

If a fertilised egg has chromosomal problems, it can go on to implant in the uterus but the resulting embryo will stop developing or will fail to form at all.

While the woman may continue to have pregnancy symptoms, and a pregnancy test will show a positive result, an ultrasound will indicate an empty gestational sac or lack of heartbeat, confirming a miscarriage.

An embryo’s heartbeat can usually be detected on ultrasound from six weeks.

If you reach the six-week mark without experiencing miscarriage symptoms, such as cramping and bleeding, your chances of having a healthy pregnancy increase.

Why do late miscarriages happen?

If a woman experiences a miscarriage during the second trimester of pregnancy, between 14 and 26 weeks, it may be due to a health problem on the mother’s side.

Diabetes and high blood pressure are known to increase the chances of experiencing a second trimester miscarriage. Kidney disease and thyroid issues can also contribute.

Pregnant women are routinely monitored for infections throughout their pregnancy.

STIs, including HIV, syphilis and chlamydia can endanger a pregnancy in addition to German measles and Rubella.

What increases the risks of miscarriage?

Miscarriage can happen for a variety of reasons but there are factors that can increase the risks.

    • Age: The mother’s age has an influence with older mothers being more at risk. One in 10 pregnancies for women under 30 will result in miscarriage, increasing to two in 10 for women between 35-39 years.

For women over 45 years, more than half of pregnancies will miscarry.

    • Lifestyle: Obesity, smoking, drinking alcohol and drug taking can all increase the likelihood of a miscarriage.

Pregnant mothers are also advised to avoid certain foods, including uncooked meats, unpasteurised cheese, which increase the risk of food poisoning.

    • Problems in the womb: An abnormally shaped uterus and fibroids, or non-cancerous growths can all increase the chance of miscarriage.

A weakened cervix, where the muscles in the neck of the womb are weaker than normal, can cause the cervix to open and prevent a pregnancy from going to term.

If you notice any unusual symptoms during your pregnancy, including bleeding or cramping, call your GP or midwife immediately.

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