LOST your heater
creates another human being and the baby was a source of heat-energy.
You acclimated slowly to the growing baby so it was less noticeable. Then in short period of time that little heat source is gone and you shiver. Adults produce 116 watts/hr (2400 kcal/day) on average, a newborn produces 19 watts/hr (116 kcal/kg/day).