I'm 24 plus weeks pregnant with twins and the thought of walking around the zoo for me would be crazy. After about 10 minutes of walking now I start getting BH and also pain in my "bits" due to the weight and pressure, plus even now I walk soooooo slow it would take forever for me to get around. Plus if it was a slightly warm day I would end up with swollen hands and feet in no time.

It would depend on how you feel within yourself if you could manage it, but I personally would be avoiding it if possible.