Kate Middleton's Royal Morning Sickness Highlights Rare Condition, Raises Odds For Princess Birth

The Duchess of Cambridge's condition was revealed after she checked into King Edward VII Hospital to be treated for acute morning sickness. The royal family confirmed the pregnancy in a statement on Monday and said Kate was about 12 weeks along.

“The Queen, the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall and Prince Harry and members of both families are delighted with the news,” the palace said in a statement.

Kate had recovered enough to head back to Kensington Palace on Thursday. But her otherwise uneventful hospital stay was marred by a joke gone tragically wrong: A pair of Australian disc jockeys made a prank phone call to the hospital and convinced a nurse to reveal details about the Duchess' condition. On Friday, Jacintha Saldanha, another nurse at the hospital who was working as a receptionist and who put the DJs' call through, was found dead in an apparent suicide on Friday.

While most pregnant women will experience nausea at some point during gestation, mostly during the first trimester, in a fraction of cases the vomiting becomes so severe that the mother must be hospitalized. This more severe form of morning sickness is known as hyperemesis gravidarum. Sometimes severe vomiting is accompanied by other symptoms, like dark urine or little urination, dizziness and vomiting blood.

Hyperemesis gravidarum can be risky if left untreated. The uncontrolled vomiting can cause severe dehydration, muscle wasting, imbalanced electrolytes and weight loss of more than 5 percent of a mother's body weight. Other possible complications include jaundice, kidney failure and other serious adverse events, including death.

If a mother was already underweight and the condition prevents her from gaining a healthy amount of pounds, the baby may be born underweight. In rare cases, the severity of the vomiting can cause tears in the mother's esophagus, according to the Mayo Clinic.

English novelist and "Jane Eyre" scribe Charlotte Bronte officially died of tuberculosis in 1855, but some biographers have speculated that the then-pregnant author actually perished from hunger and dehydration caused by severe vomiting and nausea.

A family friend remarked after Bronte's death that “a wren would have starved on what she ate during those last six weeks,” according to Bronte contemporary Elizabeth Cleghorn Gaskell.

Until the advent of modern medicine, many women turned to homemade remedies to cure their morning sickness. Raspberry leaves, mint, lemons and ginger were all common ingredients in folk medicines to combat pregnancy-related nausea.

The most common treatment for severe morning sickness in a hospital is the administration of intravenous fluids. Mothers can also try to relieve symptoms by modifying their diet -- smaller amounts of food and fluids, with foods that are heavier on carbohydrates and proteins than fats and acids.

Many doctors will avoid prescribing anti-nausea drugs to pregnant women before they are 12 to 14 weeks along, for fear of harming the developing fetus. But in severe cases of morning sickness like Middleton's, the danger from vomiting may outweigh the possible danger from drugs. One of the more commonly prescribed anti-vomiting drugs for severe morning sickness is ondansetron, sold commercially as Zofran, which is also given to combat nausea in chemotherapy patients.

Wake And Bake For Morning Sickness?

A less conventional method that Middleton could try to alleviate her pain is through medical marijuana. One survey of 84 women published in 2006 found that of the 40 women who used cannabis to treat nausea during pregnancy, 37 said the drug was "effective" or "extremely effective" at alleviating their symptoms. It's still somewhat unclear what effect cannabis use early in a pregnancy would have on a child -- a small study conducted in 1991 in Jamaica found no significant differences in developmental scores between children of marijuana users and children of mothers who abstained.

In the U.K., there are only two truly legal cannabis-based medicines: the synthetic cannabinoid Cesamet and the cannabis-derived Sativex. Neither drug has been tested in a controlled trial of pregnant humans, but animal studies of Cesamet have shown that the drug carries risks for the fetus.

If the Duchess of Cambridge did use marijuana to relieve her pains, she probably wouldn't be the first British royal to do so. Nineteenth-century monarch Queen Victoria reportedly took marijuana tea on the advice of her court physician to relieve menstrual cramps.

It appears that there is no single cause of severe morning sickness, though the hormonal changes inside a woman's body that are brought on by pregnancy are thought to play an important role. Human chorionic gonadotropin -- the chemical flag that pregnancy tests measure -- spikes in a woman's first trimester.

Another sex hormone that rises during pregnancy is progesterone. This hormone appears to play a key role in helping keep the developing embryo inside the uterus by relaxing smooth muscle tissue and is critical to maintaining early pregnancy. If, before seven weeks' gestation, progesterone levels are artificially lowered by removing the corpus luteum -- a temporary structure that develops during the menstrual cycle and secretes progesterone during pregnancy -- abortion is induced. The abortion pill mifepristone, more commonly known as RU-486, blocks the action of progesterone.

Conversely, some women with a history of preterm birth may be treated with progesterone supplements to help them carry to term.

Progesterone's activity on uterine smooth muscle may help maintain an early pregnancy, but it's also thought to inadvertantly work on smooth muscle tissue in the mother's intestines, slowing down her rate of digestion and causing numerous problems, including bloating, flatulence and an upset stomach.

Baby Girls Make For Queasier Stomachs

It's likely that Kate's condition means that the U.K. will be welcoming a little princess several months from now.

One study conducted by doctors at the James Paget Hospital in the U.K. examined nearly 10,000 women to see if hyperemesis gravidarum occurred more often in women that were carrying female fetuses.

Based on the data, “it can be concluded that women presenting with [hyperemerisis gravadum] are more likely to have a female fetus,” and that women with severe morning sickness that are carrying daughters are more likely to be admitted to the hospital, the authors wrote in the Journal of Obstetrics & Gynaecology this past July.

If Kate is carrying a girl, the child will still be third in line for the throne -- after her grandfather Prince Charles, and her father, Prince William -- thanks to upcoming changes to the royal laws of succession. The old laws dictated that a daughter would inherit only if a monarch had no other sons. While the change has not yet officially been passed yet, the heads of all the British Commonwealth governments signaled their willingness to go along with the change at a meeting in Australia in 2011.

With the Duchess of Cambridge's condition becoming public, the House of Commons is moving quickly to approve the official changes.

Hyperemesis gravidarum is also thought to be associated with multiple pregnancies -- twins or triplets or even more. In accordance with this, the U.K. betting house Paddy Power has raised the odds on Kate having twins from 28-to-1 to 6-to-1, and it set the odds for a set of royal triplets at 50-to-1, up from 1,000-to-1.

Commoners Suffer Without Sympathy

Women suffering from hyperemesis gravidarum who don't also happen to be royalty can find it hard to garner sympathy, since morning sickness is commonly assumed to be a natural part of pregnancy.

“A lot of women are treated really badly,” obstetrics researcher Marlena Fezjo told the New York Times on Monday. “They’re treated like they’re faking it or that they just don’t want their child.”

In a 2007 study of 808 women with severe morning sickness, 123 had terminated at least one pregnancy due to their condition. More than half of those women said they chose an abortion because they feared that they or their baby would die, and two-thirds said they felt they would not be able to care for their families or themselves.

Subjects that aborted were also three times more likely to say that their doctors “were uncaring or did not understand how sick they were,” University of Southern California researchers wrote in the journal Contraception.