Twins and triplets occur more frequently these days as more and more women seek fertility treatments, simply because these treatments often yield multiple births. Whether by taking fertility drugs that stimulate the ovaries, or by having several embryos implanted at once, a woman can easily conceive twins or triplets by artificial means.
However, there are still many natural ways to increase your chances of having twins. Even if there is no family history of twins on your maternal side, you can make your body an environment that is favorable to twins or triplets.
First, understand the two types of twins that can occur: monozygotic (identical), and dizygotic (fraternal). Identical twins arise when a fertilized egg splits into tow identical embryos. Fraternal twins arise from two separate eggs being fertilized by two different sperm.
It is easier to engineer the conception of fraternal twins, than the conception of identical twins.
To increase your chances of having twins or triplets, you must first increase your chances of having a baby at all. This means taking folic acid every day, starting several months before you think about conceiving. Putting on more weight, quitting alcohol and tobacco, and consuming more dairy will also help you get pregnant.
Start eating foods that will encourage your ovaries to release more eggs during the ovulation cycle. For example, yams have compounds that over-stimulate the ovaries, and women who eat them regularly before trying to conceive have a higher rate of conceiving fraternal twins and triplets.
Foods that encourage progesterone production, such as walnuts, whole grains, eggs, and chicken, can also help you conceive multiples.
Try to conceive when you are older. Between the ages of 20 and 30, a woman has a 3% chance of naturally conceiving multiples. But between the ages of 30 and 40, that rate jumps to 6% for naturally conceived twins and triplets.
Note that these are figures for naturally conceived twins and triplets. Among older women, the rates of artificially induced multiples is much higher.
Know that your chances of conceiving twins increases as you have more children. This is true not only because of the laws of probability, but also because having a child makes you gain weight. This extra body weight encourages twins.
Try to conceive shortly after you stop taking hormonal birth control. This is not a surefire method of having twins, but in a small percentage of women, the ovaries start releasing more eggs when birth control is stopped, which in turn increases the chances of fraternal twins.
(Most women actually experience a brief period of infertility when they stop taking the pill.)
Understand that none of these tricks are foolproof, and they won't help everyone conceive triplets or twins. Genetics is the biggest factor in whether or not you have multiples, but changing external factors can tip the scales in your direction.