A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, mouth, larynx (voice box), bladder, kidney, and several other organs.

But risk factors don't tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And some people who get the disease may not have any known risk factors. Even if a person has a risk factor, it is often very hard to know how much that risk factor may have contributed to the cancer.

Researchers have found several risk factors that may increase a woman's chance of developing gestational trophoblastic disease (GTD).

Age

Gestational trophoblastic disease occurs in women of childbearing age. The risk of complete molar pregnancy is highest in women over age 40 and younger than 20. The risk is even higher for women over the age of 50, in whom one-third of pregnancies results in a complete hydatiform mole. Age is less a factor for partial moles.

Prior molar pregnancy

Once a woman has had a hydatidiform mole, she has a higher risk of having another one. The overall risk for later pregnancies is about 1% to 2%. This risk increases further if she has a history of more than one molar pregnancy.

Prior miscarriage(s) or problems getting pregnant

Women with either of these have a higher risk of GTD, although their overall risk is still low.

Blood type

Women with blood type A or AB are at slightly higher risk than those with type B or O.

Birth control pills

Women who take birth control pills may be more likely to get GTD when they do become pregnant. The link between the use of birth control pills and GTD is weak, and may be explained by other factors. This risk seems to be higher for women who took the pills longer. But the risk is still so low that it doesn't outweigh the benefit of using the pills.

Socioeconomic status

Some studies have found that lower socioeconomic status is linked with an increased risk, although the reasons for this are not clear. Some researchers have suggested that diet may play a role.

Diet

A few studies have found that a low level of beta-carotene (a nutrient converted to vitamin A in the body) in the diet may be linked with a higher risk of complete molar pregnancies. More research is needed to confirm this.

Family history

Very rarely, several women in the same family have one or more molar pregnancies.

Last Medical Review: 10/13/2009
Last Revised: 10/13/2009