In an apartment you share common walls with others living there. Insects can move freely between all of the residences. If everyone is equally as aggressive at the task of eliminating the pests, you would be more successful than being the only one trying.
Its harder to get rid of pest infestations in apartment buildings because the pests have a larger area to invade, repopulate, and hide from things like predators and exterminators. This makes the job of an exterminator especially difficult because they would have to sweep the whole building to get rid of the pests rather than one apartment.
While pregnant your placenta makes hormones that cause a glucose buildup in your blood. Your pancreas can usually send enough incline to handle it but if your body cant make enough incline or stops using incline like it should, there will be to much sugar in the blood therefore developing gestational diabetes.