First things first, what is a cryptic pregnancy?

It is a pregnancy where there is little or no detectable hCG (human chorionic gonadotropin) in the mother’s system.

This is the hormone that makes a home pregnancy test turn positive. A baby that produces a scant amount amount of HCG might go "under the radar," failing the pregnancy test and going undetected by the mother.

What causes a cryptic pregnancy?

It appears that cryptic pregnancies occur when women suffer from a hormonal imbalance.

This can be due to:

Polycystic Ovarian Syndrome (PCOS).

Perimenopause (which can begin as early as age 30)

A recent pregnancy (hormones may not have time to go back to normal before falling pregnant again)

The woman is still breastfeeding

The woman has a very low body fat percentage

The woman has recently used, or is currently using, a birth control method such as the "Norplant", "Deprovera" Injection or the "Mirena Coil", that continually releases hormones into the body.

According to some doctors, a cryptic pregnancy can also be caused when the woman is simply stressed out. Apparently, in this case, it's in the foetus's best interest for the mother to be happily oblivious to the fact that she's pregnant.