Statistically, the number of multiple pregnancies has increased dramatically over the past two decades. So if you're expecting, and wonder if two (or more!) might be on the way, you're definitely not alone! What are your odds of having twins or multiples? Here are four factors:

1. Your age

Experts believe one reason for the higher incidence of multiple pregnancies is the trend for women to have babies later in life. If you're over the age of 35, you're more than twice as likely to become pregnant with twins than if you're under 25. This happens because your body naturally produces more ovulation-stimulating hormones with age, which could trigger the ovaries to release multiple eggs each month.

2. The use of fertility treatment

Older couples are also more likely to seek fertility drugs and treatments to assist conception. Fertility or ovulation-inducing drugs can stimulate the ovaries to release several eggs at the same time; while in-vitro fertilization can introduce multiple embryos into the uterus or fallopian tubes, increasing the odds of having twins.

3. Your family history

Fraternal (non-identical) twins tend to run in the family, usually on the maternal side. If your mother has twin relatives, you're more likely to carry a gene that causes you to release more than one egg at a time.

4. Your size

You could be more likely to have twins if you're overweight or tall, according to a American College of Obstetrics and Gynecology study, which reported an increase in fraternal twin births to mothers who had a BMI of 30 or higher, or who were in the top 25th percentile for height.