Pregnancy Odor Reveals Unborn Baby's Sex

A pregnancy perfume broadcasts whether a female is pregnant, and even reveals the sex of her unborn infant. Continue reading →

It's long been suspected that males of many species, including humans, can sniff out whether a female is pregnant, and now new research suggests that some - if not all - female primates release a natural "pregnancy perfume" that males can probably detect.

What's more, such scents appear to broadcast whether the mom-to-be is carrying a boy or a girl.

The study, published in the journal Biology Letters, focused on lemurs as a model for primates. It presents the first direct evidence in any animal species that a pregnant mother's scent differs depending on the sex of her baby.

The scent signatures "may help guide social interactions, potentially promoting mother–infant recognition, reducing intragroup conflict" or sort out paternity, wrote authors Jeremy Crawford and Christine Drea.

The latter presents a loaded scenario, as it could be that males can sense - even before the birth - whether they fathered the baby.

The researchers additionally suspect that odors advertising fetal sex may help dads and moms prepare for what's to come.

Crawford, from the University of California, Berkeley, and Drea, from Duke University, used cotton swabs to collect scent secretions from the genital regions of 12 female ringtailed lemurs at the Duke Lemur Center in Durham, N.C., before and during pregnancy.

The scientists next used chemical analysis to identify the hundreds of ingredients that make up each female's scent change during pregnancy. A surprising finding from this is that expectant lemur moms give off simpler scents that contain fewer odor compounds compared with their pre-pregnancy bouquet. The change is more pronounced when the moms are carrying boys, Drea said.

She and Crawford found that the patterns correlate with changes in blood hormone levels.

"The difference in hormone profiles between pregnant lemurs carrying sons and those carrying daughters is dramatic," she said in a press release.

Baby Born Pregnant with Her Own Siblings

"It could be that producing these compounds uses resources that are directed elsewhere when they're pregnant, especially if it's more energetically costly for a female to have a male pregnancy than a female pregnancy," she added.

Presumably, a male's ability to detect pregnancy - and his possible connection - is particularly important for sexually promiscuous species. Lemurs and most other primates fall into that category. Humans do too.

Lemurs are not regarded as being the best scent-detectors, so it could also be that the release of the odors and detection of them are quite common throughout the animal kingdom.

Dads often get a bad rap in the animal kingdom, but many animal moms engage in behavior that would never be celebrated in a Mother’s Day card. Here, we highlight just a few, beginning with this mustachioed mom. Female mustached tamarins sometimes kill their babies. “Genetic analysis enabled us to show that the mothers themselves take the lives of their own offspring,” said Yvan Lledo-Ferrer, an Autonomous University of Madrid researcher who co-authored a study on the primates. Lledo-Ferrer, however, explained that mothers perpetrate infanticide that have poor prospects for survival due to the social make-up of particular groups. Nevertheless, it's pretty horrific. The moms sometimes just pick up an infant and toss it to the ground from a tree branch high above the forest floor.

Like a chimp mom version of Bonnie and Clyde, sometimes chimpanzee mothers cooperate with their daughters to kill other chimps. In the 1970s, noted primatologist Jane Goodall documented this behavior in Passion and Pom, a deadly mother/daughter murdering duo. She and her team observed them killing and cannibalizing at least two infant offspring of other females. Simon Townsend and colleagues of the University of St. Andrews, Scotland, believe that the killings result when females are under pressure to compete for foraging areas. Not all female chimpanzee mothers and daughters do this, as the peaceful-looking pair in this image shows.

Some zebra finch mothers like to fool around. There is some equality here, as male zebra finch dads can do this too. “This means a male and a female will hang out together as a couple; they will build nests together and share other forms of bonding,” Wolfgang Forstmeier, a researcher in the Department of Behavioral Ecology and Evolutionary Genetics at the Max Planck Institute for Ornithology, told Discovery News. “They may also, however, engage in extra-pair mating behavior.” As if that isn’t bad enough for the offspring, Forstmeier’s investigations found that promiscuous behavior can be inherited. “The study provides a good explanation for what we see in humans,” Forstmeier said. “Statistics have shown that promiscuous parents are more likely to sire sons and daughters with a greater tendency to cheat.”

Mothers sometimes risk their own lives for the sake of their children. When times are tough for female kangaroos, however, they may sacrifice their offspring. This can happen when kangaroo mothers have three or so young at different stages of development: one in the body, one in the pouch, and one that lives mostly outside of the pouch. A starving or otherwise physically stressed female kangaroo may leave the older infant to his own devices and ditch the pouch, leading to the possible death of multiple offspring at a time.

In the case of lions, it is not so much what they do that’s bad, but what they don’t do. When a dominant male takes over a pride, he may kill numerous cubs less than 2 years old to rid himself of competition. The lioness allows this to happen, and even may go into heat, permitting the takeover male to start his own family with her.

Photos: Lions Captured in the Wild

Giant panda moms don’t mean to be bad, but sometime they cannot help it. Weighing up to 280 pounds, these large mammals have incredibly tiny offspring. At birth, most cubs typically weigh just 3.5 to 7 ounces. Giant panda mothers have been known to squash their infants by stepping on them or rolling over them in their sleep.

Photos: A Summer of Panda Pregnancies

The pregnant seahorse shown here is actually a male. Seahorses are another example of animal mothers being bad not for what they do, but what they don’t do. In this case, males take care of nearly everything, with pregnancies being exceptionally physically challenging, as this photo suggests. “The most advanced form of male parental care is found in the seahorses, where a brood pouch has evolved that resembles a placenta, and male seahorses even go into labor,” Peter Teske, a postdoctoral researcher in Macquarie University’s Molecular Ecology Lab, told Discovery News.

Photos: Small World Under the Sea

Queens and workers of the appropriately named Dracula ant chew holes into the colony’s own larvae, feeding on the insect’s “blood.” The behavior is technically called larval hemolymph feeding. It surprisingly does not kill the larvae, but it doesn't help them much either.

Photos: Faces of Bees, Flies and Friends

Many sharks consume members of their own species, and Galapagos sharks are no exception. Hungry shark mothers are not too picky. If one finds a small shark to eat, it’s usually dinner time before any further investigation takes place to see if the small shark is a relative.

Photos: Five Fantastic Animal Fathers

Humans seem to include some of the best and worst mothers in the animal kingdom. Joan Crawford, for example, was the subject of "Mommie Dearest," a book that alleges she emotionally and physically abused at least two of her children. The book was made into a popular movie of the same name starring Faye Dunaway. Crawford, however, appeared to suffer from her own personal problems, despite her movie fame. Another daughter of hers expressed sadness about her mother’s difficult life. The good news is that most mothers -- be they human or not -- treat their offspring tenderly, ensuring successful future generations.