Though fraternal twins and identical twins are the most frequently occurring multiple births, triplets, quadruplets and even octuplets are also possibilities. The occurrence of such multiple births have greatly increased with the rise in fertility treatments.
Triplets result from pregnancies in which one, two or three eggs are fertilised. This means either one egg is fertilised and divides into three fetuses, or two eggs are fertilised and just one of these eggs divides into two fetuses, or three different eggs are fertilised and no division occurs. For each higher multiple birth the fertilisation of the eggs follows a similar pattern to that just described for triplets.
Mothers expecting to deliver multiples can also expect to experience a far shorter pregnancy than most other mothers. Triplets tend to be born between week 32 and week 35 and quadruplets can be born as early as week 28. Each additional baby will further shorten your pregnancy cycle. For this reason, the more babies you are carrying, the greater your risk for certian complications. It is very important that you always turn to your physician for advice and we highly recommend that you rely on information specific to your pregnancy as the mothers with multiple babies experience very unique pregnancies.