Women lactating without pregnancy, caused due to the increase of prolactin hormone, is a sign of infertility, say doctors.

According to doctors, this medical condition is known as hyperprolactinemia in which a woman witness loss of menstrual cycles and libido besides the production of milk.

"In hyperprolactinemia, there is a rise of prolactin hormone over the normal level. High levels interfere with estrogen production and cause changes in ovulatory cycles leading to irregular menstrual periods. Though not very common, high levels of prolactin in men can lead to loss of impotency, erectile and dysfunction," said Arvind Vaid, IVF specialist at Indira IVF Hospital here.

He said high prolactin levels in blood affect reproduction by either disinhibition or excess production from prolactinoma, which inhibits the secretion of gonadotropin-releasing hormone from the hypothalamus. 

"This decrease in level of gonadotropin-releasing hormone in turn decrease the secretion of luteinizing hormone and follicle stimulating hormone leading to infertility," said Vaid.

Proclactin's primary function is to enhance breast development during pregnancy and to induce lactation.

Though small amounts of this hormone circulate in the blood, even though a woman is not pregnant, the amounts increase during pregnancy and after birth. More than 75 per cent of the women in this condition produce milk without being pregnant.

"In some cases, changes in menstrual flow is marked along with amenorrhoea. Even on not being pregnant, breast produces milk with pain due to tissue changes there with increased levels of prolactin and loss of libido also causing vaginal dryness," said Simanti Pathak, gynaecologist at Safdarjung hospital.

About diagnosing hyperprolactinemia, doctors advised, as a first step, a blood test to check serum prolactin levels, preferably fasting. If the levels are high, further assisting tests may be required. 

"In case if the prolactin levels are very high, a tumor may be suspected and in that case, MRI of the brain and pituitary glands is advised that uses high frequency radio waves to obtain images of the tissues and the size of tumor," said Ahmedabad-based IVF expert Parth Joshi.