Do Human Pregnancy Tests Work on Orangutans?

Photo credit: Zac Mills, the Wildlife Collective

Human pregnancy tests work by detecting a hormone called Human Chorionic Gonadotropin (hCG) in urine. This hormone is only found in humans when pregnant. Orangutans produce a nearly identical version of this hormone once an embryo implants in the uterus. The chemical structure is similar enough that the antibodies in a standard human pregnancy test can detect it.

But that’s not all we have in common. Like humans, female orangutans have a menstrual cycle that lasts approximately 28 to 30 days. Females of both species have concealed ovulation, as opposed to some primates (like chimps and baboons) who develop swellings when ovulating. Orangutans have a similar gestation period to humans, with pregnancy lasting around eight and a half months.

Both humans and orangutans also have a “hemochorial” placenta. This means the maternal blood comes into direct contact with the outermost fetal membrane, allowing for a more efficient transfer of nutrients. This differs from most carnivores (like cats and dogs), ruminants, and horses. But a hemochorial placenta is also found in rabbits, guinea pigs, mice, and rats.

Orangutans have the longest “inter-birth interval” of all mammals. Mothers typically wait 7 to 9 years before having another baby, ensuring their current child is fully weaned and taught how to survive. Such a long association between mother and offspring is rare. Probably only humans have a more intensive relationship with their mothers.

We love orangutans – and we think your mum will too

Orangutan mothers are among the most patient and devoted in the animal world. They have an incredibly long period of maternal care, lasting up to eight or nine years. This is just one reason why we adore orangutans, and why we think your mum will too.

Make your Mother’s Day even more meaningful by protecting the amazing bond between mother orangutans and their young.

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