Phantom pregnancy or pseudocyesis is a relatively uncommon phenomenon that occurs in humans and other mammals. Among mammals, female cats rarely show the condition, but it is more commonly observed among female dogs.
In humans, women who have phantom pregnancy are usually at the latter end of normal reproductive life, and are often frustrated or in grief because of their inability to conceive, or because they have lost the object of their love (whether a child or a lover.)
In animals, phantom or false pregnancy is characterized by breast enlargement, milk secretion, and changes in behavior. It occurs towards the end of diestrus, the period between two successive oestrus or fertile periods (when the female “comes into heat”). It thus happens most often at 6 to 12 weeks after the last oestrus.
An animal which is showing symptoms of false pregnancy may display the following:
- Nesting: building a nest for herself
- Refusing feeds
- Weight gain: an increase in weight may occur which is comparable to that which might be expected to occur during pregnancy
- Breast changes: the breasts may enlarge and start to produce milk
- Maternal behavior
- Labor pains in a few instances
Women with phantom pregnancy may have the following symptoms:
- Cessation of menstrual periods
- Abdominal enlargement
- Breast enlargement and galactorrhea
- Morning sickness
- Weight gain
- Sensations of quickening
- False labor pains
Causes and diagnosis
In animals, as oestrus is about to begin, progesterone levels fall, while prolactin levels go up. This causes the signs of false pregnancy.
In humans, it is postulated that powerful emotions of grief, loss, or pressure exert an effect on the hypothalamus, which in turn affects the functioning of the reproductive organs, producing many of the aforementioned signs and symptoms of false pregnancy.
The possibility of a true pregnancy should always be ruled out if the woman or animal has not been rendered infertile. This can be done by palpation of the abdomen, blood tests for the pregnancy hormone human chorionic gonadotropin (or short hCG, which is at normal, non-pregnant levels), and imaging tests such as X-rays or, more recently, ultrasound scans of the abdomen.
Pseudocyesis in animals resolves spontaneously, within about one to three weeks. For this reason no specific treatment is required or recommended. If the phantom pregnancy lasts beyond three weeks, the animal should be seen by a vet. During this time, she shows the same hormonal changes as if she were really pregnant.
The symptoms of breast discomfort are due to enlarged mammary glands with milk engorgement. Relief may be obtained by applying warm and cold compresses alternately on the breasts. Another method is wrapping an elastic bandage around the animal’s abdomen.
Milk production is best suppressed by not milking out the breast secretions. This will lead to the stimulation of more lactogenic hormones, prolonging milk secretion. Sometimes food and water restriction may be advised if she is producing a lot of milk.
If there are significant and disturbing changes in the animal’s behavior, such as persistently refusing all food, some vets may prescribe tranquillizing drugs such as a benzodiazepine. Progestins such as megestrol acetate are standard treatment for pseudopregnancy in female dogs.
However, it is associated with the possibility of pyometra, or collection of pus within the endometrial cavity, if its use is carried on too long, or it is administered repeatedly. Androgens are also useful in suppressing the signs of pseudopregnancy, but are not approved for this purpose in the US.
Cabergoline, an ergot derivative, has also been found to suppress false lactation and restore oestrus in over 90% of bitches and female cats with false pregnancy. Definitive treatment for repeated episodes of pseudopregnancy is by either letting the animal undergo breeding, or by removing the reproductive organs, that is, the uterus and the ovaries.
Pseudocyesis in humans is hard to treat because of the emotional reaction to the discovery that there is no fetus. Women may become angry or depressed at the news. Counseling, psychotherapy, and family therapy may all be necessary to help the woman recover from the condition.
Reviewed by: Dr Tomislav Meštrović, MD, PhD