Although IVF is considered a minor procedure as it does not require any incisions or stiches. However, you may experience some reactions to the fertility drugs given during the process. Some of these side effects are mild, such as mood changes, anxiety and headaches as the drugs effect the hormone levels in your body. Since the chemical balance is affected in your body you might notice some weight gain or bloating. Fertility drugs stimulate your ovaries to work overtime and produce multiple eggs and in rare cases this may result in (OHSS) ovarian hyper stimulation syndrome, which can cause mild to severe symptoms.