The Zoo is now open! All guests, including Zoo members, must now reserve free, timed tickets prior to visiting.

Review the Zoo’s reopening guidelines and make a reservation

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September 09, 2020

Utamu: Path to Motherhood Part III – Discovering a pregnancy

So just how did the primate care team find out that Utamu was pregnant you might wonder?

It might be helpful to begin with a little background information on chimpanzee female reproductive cycles.

Chimpanzees have about a 36-day reproductive cycle. The primate care team is able to track this cycle for all the female chimpanzees as part of our daily husbandry monitoring. When a female is ovulating or “can become pregnant,” she develops what is called an estrus swelling. Her behind swells up looking a little like a small inflated pink balloon. For the rest of her cycle, this area is deflated and has loose pink skin. Female chimpanzees also menstruate during their cycle. So if one of these events is missing or late, it can often be the first indication of a potential pregnancy to the primate care team.

How do we confirm a chimpanzee pregnancy?

We use an at home pregnancy test, the exact same type that you would use to confirm a pregnancy for a human! Utamu is trained to urinate when asked and this can then be collected and applied to a home pregnancy test.

We also have a secondary method to confirm pregnancy:

You might not know this but the Saint Louis Zoo has its own endocrinologist, Corinne Kozlowski, Ph.D., and an endocrinology laboratory. One way to have a secondary verification of a chimpanzee pregnancy is to compare progesterone levels of a suspected pregnant chimpanzee to progesterone levels of a non-pregnant female chimpanzee. Progesterone levels rise during pregnancy. The care team is able to submit fecal samples from the chimpanzees collected during daily cleaning to the lab where Dr. Kozlowski can evaluate them.

Continue to follow Utamu: Path to Motherhood to learn more about Utamu’s pregnancy and the work being done by Saint Louis Zoo staff in preparation for the upcoming birth.

Photos: 1. Utamu with full estrus swelling. 2. Rosebud with no estrus swelling. 3. Utamu's pregnancy test. 4. Utamu's progesterone. 5. Normal progesterone.