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Fibroids and Pregnancy

Fibroids are the commonest type of benign tumors to grow in the womb. They are extremely common and the prevalence is estimated to range between 20 and 50% of all adult womenTypes of fibroids. They are commonest among women of black African ancestry but they are seen in women of all races. The prevalence increases with increasing age and therefore they are rarely seen in women in their teens or early 20s. They are commonest in women in their 30s and 40s. They will tend to gradually shrink after the woman has gone through menopause, which usually occurs in the late 40s and early 50s.

Fertility and body weight are factors in the presence of fibroids as they tend to be commoner among women who remain childless and those who are overweight or obese. The two are independent factors.

Fibroids come in different sizes. They can be smaller than a pea and on the other end of the spectrum bigger than a melon.

Fibroid’s effect on Fertility:

Fibroids can be a factor in fertility difficulties for an individual even though they are a minor factor in the overall infertility and sub-fertility sphere, being significant in less than 3% of all cases.

What this means is that, even though very common, fibroids are normally inconsequential when it comes to conceiving and successfully carrying a pregnancy.

Types of Fibroids

For some women, however, fibroids do turn out to be a negative factor or a direct cause of fertility problems. Fibroids that tend to be problematic are those that grow inside the womb cavity. These are called submucosal fibroids. The other (two) types of fibroids are the ones known as intramural and subserosal. The former grow and are embedded within the wall of the womb and the latter grow outside the womb-cavity appearing to be attached to the womb on the outside. There is no evidence that either of these two types could influence fertility.

Some sub-mucosal fibroids grow to a size which virtually fills the womb cavity. A fibroid does not have to be very big to achieve this since a non-pregnant womb is usually rather small, no more than a little girl’s fist. When the cavity is so filled, it may be difficult for an embryo to implant. In some cases, implantation takes place successfully but miscarriage follows because of the less than ideal environment. Some fibroids could block one or even both openings of the fallopian tubes thus curtailing fertilisation or movement of the fertilized egg into the womb cavity for implantation.

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Fibroids and Pregnancy

Those fibroids within the womb cavity could influence fertility

multiple uterine fibroids (myoma)



The image below shows an enlarged and grossly distorted uterus because of the presence of multiple fibroids (see inset for details). These fibroids are growing on the outer wall of the uterus (subserosal fibroids) and such fibroids are unlikely to have a significant impact on fertility. That is, unless there more fibroids within the uterine cavity.