when a woman finds out she is pregnant with twins, she usually feels every emotion from panic to elation. Most doctors will advise women pregnant with twins that their pregnancies are at a higher risk for complications and premature birth of the babies. However, each woman's risk factor for complications depends on her individual situation. For example, if a woman has a family history of diabetes or high blood pressure, her doctor will undoubtedly monitor her for these specific complications.
In general, doctors and studies have identified several aspects of a woman's history and habits that can affect the outcome of a multiple pregnancy.
Maternal Age
A woman's chance of conceiving fraternal twins increases with age, and peaks between the ages of 35 and 39. Pregnancies are also riskier in general for women over 35, because the risk of common complications such as pre-eclampsia (especially if it is a first pregnancy) and diabetes go up, along with the risk of genetic abnormalities.
Women under twenty also have a higher risk for a complicated pregnancy. Those between 20 and 35 tend to have easier pregnancies than those on either side of that range.
Maternal Height and Weight
Taller and heavier women tend to conceive twins more often, probably because their body size allows for the growth of twins. While being tall has little effect on a pregnancy, shorter, petite women may find that a twin pregnancy puts a higher strain on their bodies.
Women who are obese when they become pregnant (with twins or single babies) are at a higher risk for complications, and should consult their doctors about recommended weight gain during the pregnancy.
Previous Pregnancies
Women who have carried at least one baby to term usually have easier twin pregnancies than those who are pregnant for the first time. Because the uterus has been stretched out already, the babies are usually not as constricted, and the woman's body tends to adjust more easily to the extra demands of a twin pregnancy.
Identical vs. Fraternal Twins
Identical twin pregnancies may be higher risk, depending on several factors. Identical twins in the same sac run the risk of cord accidents and Twin-to-Twin Transfusion Syndrome. Such pregnancies need to be carefully monitored by a doctor specializing in multiple pregnancies.
Maternal Diet
The research of Dr Barbara Luke has indicated that eating a large, varied diet high in specific nutrients can make for a healthier twin pregnancy. Her website, linked to below, contains great information on the subject, as does her book.
Maternal Stress
Even before the advent of modern medicine, doctors have known that stress affects pregnancies in a negative way. While stress is difficult to manage sometimes, expectant mothers who engage in relaxation techniques or other methods of stress management on a regular basis tend to have healthier pregnancies | 
