A general practitioner is similar to a family practitioner in that they treat patients of all ages with a variety of health concerns. These doctors treat everyday ailments, some acute and chronic diseases, and also provid health checkups, physicals, inoculations and preventative care.
General practitioners differ from family practitioners because they are not required to complete an additional residency in family medicine after completing their medical school residency. Like family practitioners, general practitioners will also provide referrals to patients who are in need of a specialist.

The main responsibility of a perinatologists, also known as a maternal-fetal medicine specialist, is to treat, monitor and assist pregnant mothers through high-risk pregnancies. This includes high blood pressure, early labor and bleeding. They’re also able to identify birth defects and then recommend necessary treatments to support your baby before he/she is born.
Other reasons you may need to see a perinatologist during your pregnancy include diabetes, problems with a previous pregnancy or carrying twins. Having completed OB-GYN training, they’re experts on the female reproductive system with additional specialized training in un-routine pregnancies. So, whether you know you’re at risk going into your pregnancy or problems arise unexpectedly, perinatologists can help you.

An internist is a physician who focuses on the diagnosis and treatment of conditions that affect the adult population—both acute and chronic.
These doctors are often who adults see as their primary physicians because they treat a broad range of illnesses that do not require surgical or specialist interventions. They also work to help a patient maintain optimal health in order to prevent the onset of disease.
In addition to treating the common cold and flu, internists also treat chronic diseases like diabetes and heart disease.