Causes of Ectopic Pregnancy
The causes of ectopic pregnancy relate to anything that interferes with the normal movement of a fertilised egg through the fallopian tube. In a healthy pregnancy, the egg travels freely from the ovary to the uterus. When this pathway is blocked, narrowed, or damaged, the egg may implant in the wrong location, resulting in an ectopic pregnancy.
One of the leading causes is damage to the fallopian tubes. This can result from:
Pelvic inflammatory disease (PID), often caused by untreated sexually transmitted infections such as chlamydia or gonorrhoea
Previous surgeries involving the fallopian tubes or pelvis
Scar tissue from endometriosis or past ectopic pregnancies
Tubal abnormalities—either from birth or acquired—can also prevent the egg from reaching the uterus. Infections and inflammation may reduce the mobility of the cilia (tiny hair-like structures) inside the tube, which normally help push the egg along its path.
Use of fertility treatments or assisted reproductive technology (such as IVF) increases the risk slightly, especially if there are underlying issues with the fallopian tubes. Women who become pregnant while using an intrauterine device (IUD) also have a higher chance of the pregnancy being ectopic, although this is rare.
Smoking is another risk factor. Research shows that smoking can affect the function of the fallopian tubes, making it more likely for an egg to implant outside the uterus. Age also plays a role—women over 35 are more likely to experience an ectopic pregnancy than younger women.
Causes of Ectopic Pregnancy
In South Africa and other low- and middle-income countries, the risk is higher in areas with limited access to sexual health services. Many women do not receive prompt treatment for infections, leading to long-term damage and scarring of the reproductive tract.
It’s important to note that in many cases, no specific cause is found. Even women with no risk factors can experience an ectopic pregnancy. This is why early pregnancy monitoring and attention to unusual symptoms are so important.
Understanding the causes of ectopic pregnancy helps in both prevention and early intervention. Addressing risk factors like untreated infections, smoking, and lack of reproductive healthcare can reduce the incidence and improve outcomes.
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