Because I am a sucker for the bizarre case study, I can't help but use The Frontal Cortex's recent entry on false pregnancy as an excuse to share an extreme example of the phenomenon with the readers. In Phantoms In The Brain, V.S. Ramachandran relates a tale set down by Philadelphia physician Silas Weir Mitchell in the 1930s.
One day in 1932, a 32-year-old woman named Mary Knight walked into the office of her local physician, Dr. Monroe. She was nine months pregnant, but money was tight and she'd waited until the last possible moment to consult a doctor. The pregnancy had gone off without a hitch, according to Mary, but the day she presented herself at Dr. Monroe's office something felt different. The baby was unsettled. He was "kicking" and moving around. She felt sure today was the day and wanted the doctor to check her over and make sure the baby was in the right position for delivery.
Dr. Monroe proceeded to examine her and found that: "Her abdomen was vastly enlarged and low, suggesting that the fetus had dropped. Her breasts were swollen, the nipples mottled." But something was obviously wrong. The baby appeared to have no heartbeat. It was possible, Dr. Monroe thought, that he was simply turned in a strange way. For moment, he wondered if the baby might have died in the womb. Then he noticed Mary's belly button: it was an "innie." Clearly, something was terribly off: pregnant women's belly buttons are always everted.
Pseudocyesis was common enough at the time that Dr. Monroe immediately understood what had happened. In medical school, he'd been taught that:
Some women who desperately want to be pregnant--and occasionally some who deeply dread pregnancy--develop all the signs and symptoms of true pregnancy. Their abdomens swell to enormous proportions, aided by a sway back posture and the mysterious deposition of abdominal fat. Their nipples become pigmented, as happens in pregnant women. They stop menstruating, lactate, have morning sickness and sense fetal movements. Everything is normal expect one thing: There is no baby.
(Phantoms In The Brain, 213)
Dr. Monroe proceeded cautiously. Mary had wanted a baby so desperately that her mind had literally caused her body to conjure one up. She was certainly in no shape to hear the truth. Rather than break her heart, Dr. Monroe decided to play along. He told Mary she was right. She was, in fact, in labor and would deliver today. In order to save her unnecessary discomfort, he said, he would administer ether during the birthing process.
Dr. Monroe put Mary under. Once she came to, he carefully explained that there had been complications and the baby had died. Mary was distraught, but accepted his story and, while still on the table, her abdomen began to deflate. Dr. Monroe grieved for her and assumed that would be the end of it. He was wrong:
A week passed. And then, to Dr. Monroe's astonishment, Mary burst into his office, with her belly protruding as huge as ever. "Doctor!" she shouted. "I've come back. You forgot to deliver the twin! I can feel him kicking in there!
Ramachandran was compelled by this story for the same reason The Frontal Cortex grew interested in the phenomenon of false pregnancy: it is a powerful illustration of the way the mind can affect the body.
How is this possible? How can a desire become so powerful that it hijacks the physical self? Well, as Jonah mentioned in his post, no one knows for sure. Very few studies have been conducted on the condition, but doctors do know that the abdominal swelling is caused by five factors: "an accumulation of intestinal gas, a lowering of the diaphragm, a pushing forward of the pelvic portion of the spine, and a dramatic growth of the greater omentum--a pendulous apron of fat that hangs loose in front of the intestines." They've also determined that the hormones produced by the hypothalamus while in throes of pseudocyesis are identical to those produced during real pregnancy.
This tells us 'how' false pregnancies happen. But it still doesn't explain 'why?' The answer is likely a combination of factors, but Ramachandran, for one, thinks the primary reason is social pressure. And if you look at history, this explanation begins to make a great deal of sense.
In the 1700s, when childbearing was viewed as a woman's primary responsibility, pseudocyecis happened far more frequently. (Consider that on average middle class women in the 1700s and 1800s were pregnant between 17 and 22 times.) False pregnancies occurred in 1 in 200 in the late 1700s. Whereas today, when the pressure on women to procreate has begun to subside, false pregnancies happen at a rate of roughly 1 in 10,000.
This is a visceral reminder of the power of culture. It also calls to mind a study I stumbled on arguing that PMS is a cultural response to conflicting social pressures.
That is ... well, mind-bogglingly strange is a good place to start. I want to know what happened next! Did the good doctor "deliver the twin" or was the patient finally let into the secret - maybe with the aid of an ultrasound for evidence?
No ultrasounds back in 1932, my friend. Those didn't come into use until the 1950s. As for what happened to Mary's twin, I don't think Mitchell's monograph went into detail about the second pregnancy--even if it did, Ramachandran doesn't mention what happened. I assume it was "deja vu all over again," in the immortal words of Yogi Berra.
Wow---1 in 200 pregnancies in 1700 was pseudocyecis? I'd be curious to see the data from back then; diagnosis and reporting standards have changed a lot.