When a woman is coding in this situation

[GoodTaste]

A uterus at the umbilicus means that the woman is probably carrying a previable fetus at approximately 20 weeks’ gestation. When a woman is coding in this situation, it’s recommended that the fetus be delivered. Delivery is recommended not to save the fetus, but to reduce the shunting of much-needed blood to the uterus in order to help perfuse the woman’s vital organs. The fetus is sacrificed. For so many reasons, this situation is miserable.
Source: New England Journal of Medicine

Does "coding" here mean alerting?

 

[Tarheel]

The word "coding" in that context refers to a medical emergency -- a life or death situation.

 

[probus]

Usage varies slightly, but in most North American hospitals code blue means a patient is in imminent danger of death. There is a team on alert and when the code blue is called they rush to stabilize and/or resuscitate the patient. "Patient coding" implies that a code blue has been called.