Thanks guy's this helped alot
Talk to your doctor. You are underweight, but should gain weight during the pregnancy. You may need to see a nutritionist or dietician to get the vitamins and diet proper for you and your baby. There's not a high risk of death for you during or after the baby is born. The baby will, however, have issues if you do not gain weight properly during your pregnancy.
Not because of your height and weight, if that is what you are asking. Pregnancy is not a 100% guaranteed business, but nothing about being short and small makes it worse. Possibly if you had a husband who was 6'6" the doctor might be on the lookout for an unusually large baby, but think of it, women have twins and triplets all the time and do not explode or drop dead. Talk to your doctor about your worries. Good luck!