What is hyperovulation and why does it happen?
In order to reproduce, the human species needs the following: a uterus, a sperm cell and an egg cell. The exception, however, proves the rule and so it happens that sometimes not just one, but two or more egg cells mature in one cycle.
The phenomenon of hyperovulation is still not fully understood, although we know more about it than the spontaneous division of one egg cell into two identical ones. Genes, weight, height, environmental factors and diet can all contribute to hyperovulation, i.e. two or more egg cells maturing during one menstrual cycle and being released into the fallopian tubes. It is possible that several egg cells mature in only one ovary or in both at the same time. In most cases of hyperovulation, several ovulations take place within 24 hours, but there may be several days in between. Multiple ovulation can also coincide with Polycystic Ovarian Syndrome (PCOS) and can be as problematic as in Ovarian Hyperstimulation Syndrome (OHSS).
Most women experiencing multiple ovulation, find it difficult to tell whether they are hyperovulating or ovulating at all. Which is the case, in general. In self-assessment, however, a few women also reported symptoms such as more severe ovulation pain and a heavier cervical discharge than usual. The only clear indication of hyperovulation is given by ultrasound, which shows the single follicles in which the oocytes develop.
The fertilization and implantation of two egg cells lead to the pregnancy of fraternal twins. From three oocytes to triplets and so forth. Multiple pregnancies are more common in in-vitro fertilisation because the ovaries are more highly stimulated by the administration of specific hormones. Multiple egg cells are then artificially inseminated and transplanted into the uterus. Chances that at least one of these zygotes will implant are expected to be increased. However, it is not uncommon for several zygotes to nest which in turn results in multiple pregnancies. In naturally occurring multiple pregnancies, hyperovulating women were found to have elevated levels of the Follicle Stimulating Hormone (FSH). They are also more common in women who become pregnant shortly after discontinuing hormonal contraceptives.