A multiple pregnancy is one where two or more foetuses develop simultaneously in the uterus. This can result naturally, when the woman releases more than one egg that is fertilised and implants in her uterus. If there are two eggs, this can result in a multiple pregnancy with non-identical twins, also known as dizygotic or fraternal twins. Sometimes a single fertilised egg can divide and develop into identical or monozygotic twins. It is also important to be aware that rarely when such embryos divide, two transferred embryos could result in four pregnancies, further increasing the risks to mother and babies. An increase in monozygotic twinning has been noted with blastocyst transfer and there have been some suggestions in the medical press that ‘assisted hatching’, either by laser or acid, may also result in an increase in the incidence of monozygotic twins. Further studies are planned but this should be borne in mind by those contemplating utilising these procedures to ‘possibly’ increase their chances of successful implantation.

A multiple pregnancy is usually discovered at ultrasound, usually carried out six and eight weeks after your last menstrual period. This is usual practice after IVF and most other forms of assisted conception treatment.

A multiple birth is when more than one baby is born from a multiple pregnancy. A higher order birth is one where three babies or more are born.

The simple answer is “Yes”!

Fertility drugs, by injection or orally, are often used to stimulate follicle growth and these are often used in conjunction with Intrauterine Insemination (IUI). Conception is achieved naturally but with the increased number of follicles and hence eggs, together with the lack of control over fertilization and the number of fertilized embryos reaching the uterine cavity, there is a higher risk of multiple pregnancy. Indeed in most countries the risk of multiple pregnancies after these less controlled and less regulated treatments, used on a much larger scale, can in fact have a much more profound statistical impact. The use of these methods is often wholly medically and financially justified but they all require careful monitoring to try to avoid the very real problems of excessive response and multiple pregnancy.

One in eighty natural pregnancies result in twins but the rate from IVF is about one in five, even in countries where guidelines limit the number of embryos transferred to three and just two are routinely transferred.1

The chance of having multiple births from IVF treatment is directly related to the number of embryos transferred at each treatment. Improved results have lead to the more enlightened clinicians, who are concerned by such issues, to limit the number of embryos transferred per treatment cycle and the Reproductive Technology Accreditation Committee guidelines used in Australia strongly endorse reduced numbers at transfer.