Just because your female gourami's belly is swelling doesn't mean she's gravid. Beware of dropsy, a disease that causes abdominal swelling with protrusion of the scales. Dropsy has multiple causes, including improper nutrition, poor water quality, infection and parasite infestation and is deadly without treatment.
Just because a female is gravid and a male builds a bubble nest does not mean there will be healthy fry, or baby fish. Many factors determine the viability of eggs and the health of babies, including water quality, temperature, availability of food and whether or not they become food for larger fish in the tank. As a precaution, fry should be removed and put into their own tank immediately upon hatching.
Gouramis are common freshwater aquarium fish. There are several gourami species ranging from small to quite large. Gouramis come in a variety of colors and are relatively easy to care for. They do not get pregnant in the traditional sense, as they are egg layers who reproduce through external means. However, female gouramis do become gravid -- they swell with eggs and can potentially be bred under the right conditions. There are several steps you can take to figure out whether or not your female gourami is gravid.
Watch the behavior of your female and male gouramis. If they are swimming together with their bodies touching, this may signal potential mating, a precursor to the female's gravid state.
Look for swelling in the female's belly. As the eggs grow, her belly will expand in an isolated spot right underneath her front end. If she's gravid, it may look as if she's swallowed a marble. The scales around that area may look stretched and a little more pale.
Check for a bubble nest. Gouramis use bubble nests to hold the eggs while the embryos develop. This nest will look like a mat of bubbles floating atop the water's surface and is constructed by the male.