Fertility treatments have vastly improved over the past few years, which are allowing women to conceive and have healthy children, some into their 50’s.
Multiple pregnancies seem to be the topic of the day. Twins represent the majority of multiple pregnancies. The chance of having twins naturally is approximately 1%. Most twins are fraternal (non-identical) meaning that they each come from one egg. Fraternal twinning appears to have a genetic basis since twins tend to occur repetitively in certain families and have increased incidences in certain ethnic groups. Naturally occurring fraternal twins occur when a woman ovulates at least two eggs and both are fertilized. Usually, women ovulate one egg each month.
Identical twins are the result of a single embryo splitting into two embryos during the first 15 days of life. Identical twinning is thought to represent a random event rather than having a genetic or racial basis.