How long is a full term pregnancy? A full term pregnancy is one that lasts the full gestational period. In other words, for a human being this means nine months, or on average a term of 30-40 weeks. If a woman exceeds more than nine months it could lead to complications. Any term that is less than 40 weeks may also lead to complications but it is almost always the case in women who carry multiple pregnancies. It would be impossible for a pregnant woman to carry a pregnancy of more than two babies in nine months. The more the number of fetuses a woman Is carrying, the less the time she will be carrying them. The first three months of the pregnancy are the most crucial. This is also the time when the woman is supposed to observe the rules of dieting and exercise to the latter. Smoking and drinking is discouraged in this part of the pregnancy as it could lead to spontaneous abortion of the uterus. It could also lead to low birth weight and a lot of complications of the major organs of the baby when it is born-if it will be born, that is. At this time, the baby will be growing most of its features.