When you swallow sperm (which is part of semen), the sperm and the seminal fluid enter your digestive system, where they are broken down and digested like any other food. Swallowing sperm does not cause pregnancy because sperm must enter the female reproductive tract (via vaginal intercourse) to fertilize an egg. Regarding health effects:

• It is generally safe to swallow sperm in terms of digestion.
• Semen contains small amounts of nutrients like proteins, sugars, minerals, and vitamins, but the quantities are very small and not sufficient for nutritional benefit.
• Some people can have allergic reactions to proteins in semen (called human seminal plasma hypersensitivity), which can cause itching, swelling, rashes, and in rare cases difficulty breathing.
• The most significant risk from swallowing sperm is the potential transmission of sexually transmitted infections (STIs) such as HIV, herpes, gonorrhea, chlamydia, and human papillomavirus (HPV). This risk is higher if there are cuts or sores in the mouth.
• The taste and smell of semen can vary depending on diet, health, and hygiene.

In summary, while swallowing sperm is typically safe for digestion, it carries some risks related to allergies and possible STI transmission. It does not lead to pregnancy.