Among the UK population. the chances of having twins in the 21st century are about 1.5 in 100. or about 1.5%. Your chances are better than ever; researchers have recorded an increase of nearly 50% since the early 1980s. The most recent statistics in 2004 show that twins. triplets and quads represented 14.87 of every 1.000 births or 1 in 67 pregnancies was a multiple birth (or 1 in every 34 children is a twin/triplet).
ncreases with age; in the 2004 UK statistics. the twinning rate of mothers over the age of 35 is 21.7 per 1000 maternities and becoming a mother after age 45 boosts your odds considerably to 56.7 per 1000 !
Assisted Conception : You take fertility drugs or undergo other fertility treatments. No one can deny that the availability of fertility enhancements has increased the multiple birth rate and on average the chances of having a multiple birth after fertility enhancing treatment is around 25% although you need to account for the fact that some fertility treatments have odds of only 20% chance of becoming pregnant.
Maternal History : You. your mother. or her mother’s mother is a fraternal twin. These women may carry a gene for hyperovulation. which means they release more than one egg during an ovulation cycle. increasing their ability to conceive fraternal twins. The chances may increase if the mother is a fraternal twin herself.
Previous Pregancies : You’ve already had one set of fraternal twins. For mothers who have already had one set of fraternal twins. their chances of conceiving another set are five times greater than the average woman. or about 1 in 14 ! Women who have had more than four previous pregnancies are also more likely to conceive twins.