The vast majority of women will release one egg (or ovum) from the many millions within her ovaries during her monthly menstrual cycle. Hyperovulation is the term given when a woman releases more than one egg from her ovary, or ovaries, during this monthly cycle.
Hyperovulation is triggered by a gene, known as the 'twin gene', that causes the woman to release two or more eggs during her cycle.
As its name suggests, the twin gene does increase the chances of a multiple birth. This is normally twins, although it is possible for triplets or more to be born. This is because more than one egg is available to be fertilized and implanted into the woman's uterus.
The gene can also be passed to a woman's daughters, which is why non-identical twins tend to run in families. However, the use of fertility drugs can also cause hyperovulation, and as a result the number of twin births is on a steady increase.
There are no obvious symptoms to indicate that a woman carries the hyperovulation gene, other than a recurring pattern of non-identical twins on the maternal side of her family.
Additionally, even if a woman does carry the gene, hyperovulation may not occur on a monthly basis and can happen sporadically.