While pregnancy may seem like a simple term, there are different types of pregnancies. Most are a result of physical differences between women, but some are related to multiple egg release, among other reasons.
Intrauterine Pregnancies
These are the normal pregnancies, when the fetus or fetuses implant inside the uterus. The placenta is attached to the inside of the uterus, to the uterine muscle.
Ectopic Pregnancies and Tubal Pregnancies
Ectopic pregnancies occur when the fertilized egg implants in a place other than the fallopian tube or uterus. It can be in the neck of the uterus or in the abdomen. The pregnancy is not viable and the body will most likely spontaneously abort the fetus.
Tubal pregnancies occur when the fertilized egg implants in the fallopian tube instead of the uterus. These pregnancies are not viable and must be terminated if a miscarriage does not naturally occur.
Intra-Abdominal Pregnancies
Most intra-abdominal pregnancies occur after a previous C-section. The C-section scar may weaken and tear, allowing the fetus to slip into the abdominal cavity. The viability of the pregnancy will depend upon the gestational age of the fetus when the tear occurs. There have been cases of undetected intra-abdominal pregnancies that went to term, but a complete hysterectomy was needed after birth.
Singlet Pregnancies
Singlet pregnancies occur when one egg meets one sperm and one fetus develops.
Multiple Pregnancies
Multiples can occur as a result of multiple eggs being fertilized at the same time, when two sperm enter one egg or when one egg is fertilized by one sperm that divides into two zygotes. If more than one egg is fertilized, the pregnancies will result in fraternal twins. If one egg was fertilized by two sperm, fraternal twins will result. If one egg splits into multiple zygotes, identical twins will occur.
Natural multiples, including twins, triplets and quadruplets have been reported. During fertility treatments, multiples may be more likely and can create five or more fertilized and implanted fetuses.
Lupus Pregnancies
Pregnancies for women with lupus can be complicated by blood clotting. Lupus is an auto-immune disease.
High-Risk Pregnancies
Women over the age of 35, with diabetes and other health conditions that affect pregnancy or those pregnant with multiples may be considered high-risk due to increase risk of pregnancy complications. In some cases, the pregnancy may be termed high-risk of medications are required to control certain medical conditions that could affect the fetus. History of previous pregnancy complications could also cause high-risk pregnancies.
Molar Pregnancies
Complete molar pregnancies result in the placenta forming in the uterus without a fetus to support. Partial molar pregnancies occur when two sperm fertilize one egg, but two fetuses do not develop. The placenta is abnormal and the fetus has too many chromosomes. This always results in a spontaneous abortion as the fetus cannot develop safely.
This is a short, concise list of the types of pregnancies. Other terms commonly used by doctors include early pregnancy, first pregnancy and new pregnancy. These terms have nothing to do with the fetus or physical differences between pregnant women, they are only used to describe pregnancies and where a woman is in the pregnancy.