Gestational trophoblastic disease occurs only in women of reproductive age. An invasive mole develops in 15 to 20 percent of all complete moles and 2 to 6 percent of all partial moles. Choriocarcinoma develops in 3 percent of complete moles but rarely in partial moles.

At Significantly Higher Risk 
Risks for the development of a hydatidiform or invasive mole or choriocarcinoma include:
• A prior mole (30 times the risk). 
• Maternal age greater than 40 years (5 times) or less than 20 years (1.5 times).
• A previous spontaneous abortion (twice the risk).

At Slightly Lower Risk 
• Eating a diet high in vitamin A and having one or more children without having a previous abortion is
  statistically correlated with a lower than average risk of developing a complete mole.

At Risk for Developing an Invasive Mole or Choriocarcinoma
For women with a molar pregnancy, there are several risk factors associated with the subsequent development of an invasive mole and choriocarcinoma.