Every pregnancy does not and cannot result in birth of a live child. Out of say 100 pregnancies about 30 -40% may abort. This happens due to many factors like abnormality in the fetus, or infections, or unhealthy implantation of the fetus or uterus mouth opening prematurely. Abortions are said to occur when pregnancy gets expelled from uterus before 5 months of pregnancy.
To assess whether the fetus is fine, tests like sonography ( NT, NB scan done at 9-13 weeks, and anomaly scan done between 18-20 weeks ) and some blood tests like double, triple and quadruple markers are checked.
Even if these tests are normal, the sign of a healthy pregnancy is one which grows and remains in uterus. So growth of the fetus is the best criteria to determine its health. One cannot predict if miscarriage can occur as of now.
Next Steps
Just relax and enjoy the pregnancy. Each 3 month period of the 9 months of pregnancy has its own set of symptoms like nausea, vomits, weakness, lethargy sleepiness are common in the first three months (trimester). When uterus expels a baby it can cause cramping but if the mouth of the uterus opens, it may do silently. Also growth of the baby cannot be assessed at every visit as it is unhealthy to do sonography at each visit. In a pregnancy sonography is done at specific times of whithe ones at 9-11 weeks, 18-20 weeks are most important. Others can be guided by patients progress